constraint editor: Various minor fixes

constraint editor: Allow editing children
Just name and size, for now.
2019-07-02 22:41:07 +00:00 · 2019-07-02 22:21:07 +00:00 · 2019-07-02 21:46:38 +00:00 · 2019-07-02 14:18:42 +00:00 · 2019-07-02 10:03:48 -04:00 · 2019-07-02 10:03:48 -04:00
88 changed files with 15718 additions and 160 deletions
@@ -105,7 +105,7 @@ pages:
  image: registry.gitlab.gnome.org/gnome/gtk/master:v6
  stage: deploy 
  script:
-    - meson -Ddocumentation=true _build .
+    - meson -Dgtk_doc=true _build .
    - ninja -C _build
    - ninja -C _build gdk4-doc gsk4-doc gtk4-doc

@@ -56,12 +56,6 @@
 /* Define if GStreamer support is available */
 #mesondefine HAVE_GSTREAMER

-/* Define to 1 if you have the `httpGetAuthString' function. */
-#mesondefine HAVE_HTTPGETAUTHSTRING
-
-/* Define if cups http_t authstring field is accessible */
-#mesondefine HAVE_HTTP_AUTHSTRING
-
 /* Define to 1 if you have the <inttypes.h> header file. */
 #mesondefine HAVE_INTTYPES_H

@@ -0,0 +1,262 @@
+/*
+ * Copyright © 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#include "config.h"
+
+#include "child-editor.h"
+
+struct _ChildEditor
+{
+  GtkWidget parent_instance;
+
+  GtkWidget *grid;
+  GtkWidget *name;
+  GtkWidget *min_width;
+  GtkWidget *min_height;
+  GtkWidget *button;
+
+  GtkWidget *child;
+
+  gboolean constructed;
+};
+
+enum {
+  PROP_CHILD = 1,
+  LAST_PROP
+};
+
+static GParamSpec *pspecs[LAST_PROP];
+
+enum {
+  DONE,
+  LAST_SIGNAL
+};
+
+static guint signals[LAST_SIGNAL];
+
+G_DEFINE_TYPE(ChildEditor, child_editor, GTK_TYPE_WIDGET);
+
+void
+child_editor_serialize_child (GString   *str,
+                              int        indent,
+                              GtkWidget *child)
+{
+  int min_width, min_height;
+  const char *name;
+
+  name = gtk_widget_get_name (child);
+  if (!name)
+    name = "";
+
+  gtk_widget_get_size_request (child, &min_width, &min_height);
+
+  g_string_append_printf (str, "%*s<child>\n", indent, "");
+  g_string_append_printf (str, "%*s  <object class=\"GtkLabel\" id=\"%s\">\n", indent, "", name);
+  g_string_append_printf (str, "%*s    <property name=\"label\">%s</property>\n", indent, "", name);
+  if (min_width != -1)
+    g_string_append_printf (str, "%*s    <property name=\"width-request\">%d</property>\n", indent, "", min_width);
+  if (min_height != -1)
+    g_string_append_printf (str, "%*s    <property name=\"height-request\">%d</property>\n", indent, "", min_height);
+  g_string_append_printf (str, "%*s  </object>\n", indent, "");
+  g_string_append_printf (str, "%*s</child>\n", indent, "");
+}
+
+static void
+apply (GtkButton   *button,
+       ChildEditor *editor)
+{
+  const char *name;
+  int w, h;
+
+  name = gtk_editable_get_text (GTK_EDITABLE (editor->name));
+  w = gtk_spin_button_get_value_as_int (GTK_SPIN_BUTTON (editor->min_width));
+  h = gtk_spin_button_get_value_as_int (GTK_SPIN_BUTTON (editor->min_height));
+
+  gtk_widget_set_size_request (editor->child, w, h);
+  gtk_widget_set_name (editor->child, name);
+
+  g_signal_emit (editor, signals[DONE], 0, editor->child);
+}
+
+static void
+child_editor_init (ChildEditor *editor)
+{
+  gtk_widget_init_template (GTK_WIDGET (editor));
+}
+
+static int
+min_input (GtkSpinButton *spin_button,
+           double        *new_val)
+{
+  if (strcmp (gtk_editable_get_text (GTK_EDITABLE (spin_button)), "") == 0)
+    {
+      *new_val = 0.0;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static gboolean
+min_output (GtkSpinButton *spin_button)
+{
+  GtkAdjustment *adjustment;
+  double value;
+  GtkWidget *box, *text;
+
+  adjustment = gtk_spin_button_get_adjustment (spin_button);
+  value = gtk_adjustment_get_value (adjustment);
+
+  box = gtk_widget_get_first_child (GTK_WIDGET (spin_button));
+  text = gtk_widget_get_first_child (box);
+
+  if (value <= 0.0)
+    {
+      gtk_editable_set_text (GTK_EDITABLE (spin_button), "");
+      gtk_text_set_placeholder_text (GTK_TEXT (text), "unset");
+      return TRUE;
+    }
+  else
+    {
+      gtk_text_set_placeholder_text (GTK_TEXT (text), "");
+      return FALSE;
+    }
+}
+
+static void
+child_editor_constructed (GObject *object)
+{
+  ChildEditor *editor = CHILD_EDITOR (object);
+  const char *nick;
+  int w, h;
+
+  g_signal_connect (editor->min_width, "input", G_CALLBACK (min_input), NULL);
+  g_signal_connect (editor->min_width, "output", G_CALLBACK (min_output), NULL);
+
+  g_signal_connect (editor->min_height, "input", G_CALLBACK (min_input), NULL);
+  g_signal_connect (editor->min_height, "output", G_CALLBACK (min_output), NULL);
+
+  nick = gtk_widget_get_name (editor->child);
+  if (nick)
+    gtk_editable_set_text (GTK_EDITABLE (editor->name), nick);
+
+  gtk_widget_get_size_request (editor->child, &w, &h);
+  gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->min_width), w);
+  gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->min_height), h);
+
+  editor->constructed = TRUE;
+}
+
+static void
+child_editor_set_property (GObject      *object,
+                           guint         property_id,
+                           const GValue *value,
+                           GParamSpec   *pspec)
+{
+  ChildEditor *self = CHILD_EDITOR (object);
+
+  switch (property_id)
+    {
+    case PROP_CHILD:
+      self->child = g_value_dup_object (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+    }
+}
+
+static void
+child_editor_get_property (GObject    *object,
+                           guint       property_id,
+                           GValue     *value,
+                           GParamSpec *pspec)
+{
+  ChildEditor *self = CHILD_EDITOR (object);
+
+  switch (property_id)
+    {
+    case PROP_CHILD:
+      g_value_set_object (value, self->child);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+    }
+}
+
+static void
+child_editor_dispose (GObject *object)
+{
+  ChildEditor *self = (ChildEditor *)object;
+
+  g_clear_pointer (&self->grid, gtk_widget_unparent);
+  g_clear_object (&self->child);
+
+  G_OBJECT_CLASS (child_editor_parent_class)->dispose (object);
+}
+
+static void
+child_editor_class_init (ChildEditorClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
+
+  object_class->constructed = child_editor_constructed;
+  object_class->dispose = child_editor_dispose;
+  object_class->set_property = child_editor_set_property;
+  object_class->get_property = child_editor_get_property;
+
+  pspecs[PROP_CHILD] =
+    g_param_spec_object ("child", "child", "child",
+                         GTK_TYPE_WIDGET,
+                         G_PARAM_READWRITE|G_PARAM_CONSTRUCT_ONLY);
+
+  g_object_class_install_properties (object_class, LAST_PROP, pspecs);
+
+  signals[DONE] =
+    g_signal_new ("done",
+                  G_TYPE_FROM_CLASS (object_class),
+                  G_SIGNAL_RUN_LAST,
+                  0,
+                  NULL, NULL,
+                  NULL,
+                  G_TYPE_NONE, 1, GTK_TYPE_WIDGET);
+
+  gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_BIN_LAYOUT);
+
+  gtk_widget_class_set_template_from_resource (widget_class,
+                                               "/org/gtk/gtk4/constraint-editor/child-editor.ui");
+
+  gtk_widget_class_bind_template_child (widget_class, ChildEditor, grid);
+  gtk_widget_class_bind_template_child (widget_class, ChildEditor, name);
+  gtk_widget_class_bind_template_child (widget_class, ChildEditor, min_width);
+  gtk_widget_class_bind_template_child (widget_class, ChildEditor, min_height);
+  gtk_widget_class_bind_template_child (widget_class, ChildEditor, button);
+
+  gtk_widget_class_bind_template_callback (widget_class, apply);
+}
+
+ChildEditor *
+child_editor_new (GtkWidget *child)
+{
+  return g_object_new (CHILD_EDITOR_TYPE,
+                       "child", child,
+                       NULL);
+}
@@ -0,0 +1,32 @@
+/*
+ * Copyright © 2019 Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+#define CHILD_EDITOR_TYPE (child_editor_get_type ())
+
+G_DECLARE_FINAL_TYPE (ChildEditor, child_editor, CHILD, EDITOR, GtkWidget)
+
+ChildEditor * child_editor_new (GtkWidget *child);
+
+void child_editor_serialize_child (GString   *str,
+                                   int        indent,
+                                   GtkWidget *child);
@@ -0,0 +1,84 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <object class="GtkAdjustment" id="min_width_adj">
+    <property name="lower">0</property>
+    <property name="upper">2147483647</property>
+    <property name="step-increment">1</property>
+    <property name="page-increment">10</property>
+    <property name="page-size">0</property>
+  </object>
+  <object class="GtkAdjustment" id="min_height_adj">
+    <property name="lower">0</property>
+    <property name="upper">2147483647</property>
+    <property name="step-increment">1</property>
+    <property name="page-increment">10</property>
+    <property name="page-size">0</property>
+  </object>
+  <template class="ChildEditor" parent="GtkWidget">
+    <child>
+      <object class="GtkGrid" id="grid">
+        <property name="margin">20</property>
+        <property name="row-spacing">10</property>
+        <property name="column-spacing">10</property>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Name</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">0</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkEntry" id="name">
+            <property name="max-width-chars">20</property>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">0</property>
+              <property name="column-span">2</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Min Size</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkSpinButton" id="min_width">
+            <property name="adjustment">min_width_adj</property>
+            <property name="max-width-chars">5</property>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkSpinButton" id="min_height">
+            <property name="adjustment">min_height_adj</property>
+            <property name="max-width-chars">5</property>
+            <layout>
+              <property name="left-attach">2</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkButton" id="button">
+            <property name="label">Apply</property>
+            <signal name="clicked" handler="apply"/>
+            <layout>
+              <property name="left-attach">2</property>
+              <property name="top-attach">5</property>
+            </layout>
+          </object>
+        </child>
+      </object>
+    </child>
+  </template>
+</interface>
@@ -0,0 +1,115 @@
+/*
+ * Copyright © 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#include "config.h"
+
+#include "constraint-editor-application.h"
+#include "constraint-editor-window.h"
+
+struct _ConstraintEditorApplication
+{
+  GtkApplication parent_instance;
+};
+
+G_DEFINE_TYPE(ConstraintEditorApplication, constraint_editor_application, GTK_TYPE_APPLICATION);
+
+static void
+constraint_editor_application_init (ConstraintEditorApplication *app)
+{
+}
+
+static void
+quit_activated (GSimpleAction *action,
+                GVariant      *parameter,
+                gpointer       data)
+{
+  g_application_quit (G_APPLICATION (data));
+}
+
+static GActionEntry app_entries[] =
+{
+  { "quit", quit_activated, NULL, NULL, NULL }
+};
+
+static void
+constraint_editor_application_startup (GApplication *app)
+{
+  const char *quit_accels[2] = { "<Ctrl>Q", NULL };
+  const char *open_accels[2] = { "<Ctrl>O", NULL };
+  GtkCssProvider *provider;
+
+  G_APPLICATION_CLASS (constraint_editor_application_parent_class)->startup (app);
+
+  g_action_map_add_action_entries (G_ACTION_MAP (app),
+                                   app_entries, G_N_ELEMENTS (app_entries),
+                                   app);
+  gtk_application_set_accels_for_action (GTK_APPLICATION (app), "app.quit", quit_accels);
+  gtk_application_set_accels_for_action (GTK_APPLICATION (app), "win.open", open_accels);
+
+  provider = gtk_css_provider_new ();
+  gtk_css_provider_load_from_resource (provider, "/org/gtk/gtk4/constraint-editor/constraint-editor.css");
+  gtk_style_context_add_provider_for_display (gdk_display_get_default (),
+                                              GTK_STYLE_PROVIDER (provider),
+                                              GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+}
+
+static void
+constraint_editor_application_activate (GApplication *app)
+{
+  ConstraintEditorWindow *win;
+
+  win = constraint_editor_window_new (CONSTRAINT_EDITOR_APPLICATION (app));
+  gtk_window_present (GTK_WINDOW (win));
+}
+
+static void
+constraint_editor_application_open (GApplication  *app,
+                                    GFile        **files,
+                                    gint           n_files,
+                                    const gchar   *hint)
+{
+  ConstraintEditorWindow *win;
+  gint i;
+
+  for (i = 0; i < n_files; i++)
+    {
+      win = constraint_editor_window_new (CONSTRAINT_EDITOR_APPLICATION (app));
+      constraint_editor_window_load (win, files[i]);
+      gtk_window_present (GTK_WINDOW (win));
+    }
+}
+
+static void
+constraint_editor_application_class_init (ConstraintEditorApplicationClass *class)
+{
+  GApplicationClass *application_class = G_APPLICATION_CLASS (class);
+
+  application_class->startup = constraint_editor_application_startup;
+  application_class->activate = constraint_editor_application_activate;
+  application_class->open = constraint_editor_application_open;
+}
+
+ConstraintEditorApplication *
+constraint_editor_application_new (void)
+{
+  return g_object_new (CONSTRAINT_EDITOR_APPLICATION_TYPE,
+                       "application-id", "org.gtk.gtk4.ConstraintEditor",
+                       "flags", G_APPLICATION_HANDLES_OPEN,
+                       NULL);
+}
@@ -0,0 +1,28 @@
+/*
+ * Copyright © 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+#define CONSTRAINT_EDITOR_APPLICATION_TYPE (constraint_editor_application_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintEditorApplication, constraint_editor_application, CONSTRAINT, EDITOR_APPLICATION, GtkApplication)
+
+ConstraintEditorApplication *constraint_editor_application_new (void);
@@ -0,0 +1,662 @@
+/*
+ * Copyright © 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#include "config.h"
+
+#include "constraint-editor-window.h"
+#include "constraint-view.h"
+#include "constraint-editor.h"
+#include "guide-editor.h"
+#include "child-editor.h"
+
+struct _ConstraintEditorWindow
+{
+  GtkApplicationWindow parent_instance;
+
+  GtkWidget *paned;
+  GtkWidget *view;
+  GtkWidget *list;
+};
+
+G_DEFINE_TYPE(ConstraintEditorWindow, constraint_editor_window, GTK_TYPE_APPLICATION_WINDOW);
+
+static GtkConstraintTarget *
+find_target (GListModel *model,
+             GtkConstraintTarget *orig)
+{
+  const char *name;
+  const char *model_name;
+  gpointer item;
+  int i;
+
+  if (orig == NULL)
+    return NULL;
+
+  if (GTK_IS_LABEL (orig))
+    name = gtk_label_get_label (GTK_LABEL (orig));
+  else if (GTK_IS_CONSTRAINT_GUIDE (orig))
+    name = gtk_constraint_guide_get_name (GTK_CONSTRAINT_GUIDE (orig));
+  else
+    {
+      g_warning ("Don't know how to handle %s targets", G_OBJECT_TYPE_NAME (orig));
+      return NULL;
+    }
+  for (i = 0; i < g_list_model_get_n_items (model); i++)
+    {
+      item = g_list_model_get_item (model, i);
+      g_object_unref (item);
+      if (GTK_IS_WIDGET (item))
+        model_name = gtk_widget_get_name (GTK_WIDGET (item));
+      else
+        model_name = gtk_constraint_guide_get_name (GTK_CONSTRAINT_GUIDE (item));
+
+      if (strcmp (name, model_name) == 0)
+        return GTK_CONSTRAINT_TARGET (item);
+    }
+  g_warning ("Failed to find target '%s'", name);
+
+  return NULL;
+}
+
+gboolean
+constraint_editor_window_load (ConstraintEditorWindow *self,
+                               GFile            *file)
+{
+  char *path;
+  GtkBuilder *builder;
+  GError *error = NULL;
+  GtkWidget *view;
+  GtkLayoutManager *layout;
+  GtkWidget *child;
+  const char *name;
+  gpointer item;
+  int i;
+  GListModel *list;
+
+  path = g_file_get_path (file);
+
+  builder = gtk_builder_new ();
+  if (!gtk_builder_add_from_file (builder, path, &error))
+    {
+      g_print ("Could not load %s: %s", path, error->message);
+      g_error_free (error);
+      g_free (path);
+      g_object_unref (builder);
+      return FALSE;
+    }
+
+  view = GTK_WIDGET (gtk_builder_get_object (builder, "view"));
+  if (!GTK_IS_BOX (view))
+    {
+      g_print ("Could not load %s: No GtkBox named 'view'", path);
+      g_free (path);
+      g_object_unref (builder);
+      return FALSE;
+    }
+  layout = gtk_widget_get_layout_manager (view);
+  if (!GTK_IS_CONSTRAINT_LAYOUT (layout))
+    {
+      g_print ("Could not load %s: Widget 'view' does not use GtkConstraintLayout", path);
+      g_free (path);
+      g_object_unref (builder);
+      return FALSE;
+    }
+
+  for (child = gtk_widget_get_first_child (view);
+       child;
+       child = gtk_widget_get_next_sibling (child))
+    {
+      if (!GTK_IS_LABEL (child))
+        {
+          g_print ("Skipping non-GtkLabel child\n");
+          continue;
+        }
+
+      name = gtk_label_get_label (GTK_LABEL (child));
+      constraint_view_add_child (CONSTRAINT_VIEW (self->view), name);
+    }
+
+  list = gtk_constraint_layout_observe_guides (GTK_CONSTRAINT_LAYOUT (layout));
+  for (i = 0; i < g_list_model_get_n_items (list); i++)
+    {
+      GtkConstraintGuide *guide, *clone;
+      int w, h;
+
+      item = g_list_model_get_item (list, i);
+      guide = GTK_CONSTRAINT_GUIDE (item);
+
+      /* need to clone here, to attach to the right targets */
+      clone = gtk_constraint_guide_new ();
+      gtk_constraint_guide_set_name (clone, gtk_constraint_guide_get_name (guide));
+      gtk_constraint_guide_set_strength (clone, gtk_constraint_guide_get_strength (guide));
+      gtk_constraint_guide_get_min_size (guide, &w, &h);
+      gtk_constraint_guide_set_min_size (clone, w, h);
+      gtk_constraint_guide_get_nat_size (guide, &w, &h);
+      gtk_constraint_guide_set_nat_size (clone, w, h);
+      gtk_constraint_guide_get_max_size (guide, &w, &h);
+      gtk_constraint_guide_set_max_size (clone, w, h);
+      constraint_view_add_guide (CONSTRAINT_VIEW (self->view), clone);
+      g_object_unref (guide);
+      g_object_unref (clone);
+    }
+  g_object_unref (list);
+
+  list = gtk_constraint_layout_observe_constraints (GTK_CONSTRAINT_LAYOUT (layout));
+  for (i = 0; i < g_list_model_get_n_items (list); i++)
+    {
+      GtkConstraint *constraint;
+      GtkConstraint *clone;
+      GtkConstraintTarget *target;
+      GtkConstraintTarget *source;
+
+      item = g_list_model_get_item (list, i);
+      constraint = GTK_CONSTRAINT (item);
+
+      target = gtk_constraint_get_target (constraint);
+      source = gtk_constraint_get_source (constraint);
+      clone = gtk_constraint_new (find_target (constraint_view_get_model (CONSTRAINT_VIEW (self->view)), target),
+                                  gtk_constraint_get_target_attribute (constraint),
+                                  gtk_constraint_get_relation (constraint),
+                                  find_target (constraint_view_get_model (CONSTRAINT_VIEW (self->view)), source),
+                                  gtk_constraint_get_target_attribute (constraint),
+                                  gtk_constraint_get_multiplier (constraint),
+                                  gtk_constraint_get_constant (constraint),
+                                  gtk_constraint_get_strength (constraint));
+
+      constraint_view_add_constraint (CONSTRAINT_VIEW (self->view), clone);
+
+      g_object_unref (constraint);
+      g_object_unref (clone);
+    }
+  g_object_unref (list);
+
+  g_free (path);
+  g_object_unref (builder);
+
+  return TRUE;
+}
+
+static void
+open_response_cb (GtkNativeDialog        *dialog,
+                  gint                    response,
+                  ConstraintEditorWindow *self)
+{
+  gtk_native_dialog_hide (dialog);
+
+  if (response == GTK_RESPONSE_ACCEPT)
+    {
+      GFile *file;
+
+      file = gtk_file_chooser_get_file (GTK_FILE_CHOOSER (dialog));
+      constraint_editor_window_load (self, file);
+      g_object_unref (file);
+    }
+
+  gtk_native_dialog_destroy (dialog);
+}
+
+static void
+open_cb (GtkWidget              *button,
+         ConstraintEditorWindow *self)
+{
+  GtkFileChooserNative *dialog;
+
+  dialog = gtk_file_chooser_native_new ("Open file",
+                                        GTK_WINDOW (self),
+                                        GTK_FILE_CHOOSER_ACTION_OPEN,
+                                        "_Load",
+                                        "_Cancel");
+
+  gtk_native_dialog_set_modal (GTK_NATIVE_DIALOG (dialog), TRUE);
+  gtk_file_chooser_set_current_folder (GTK_FILE_CHOOSER (dialog), ".");
+  g_signal_connect (dialog, "response", G_CALLBACK (open_response_cb), self);
+  gtk_native_dialog_show (GTK_NATIVE_DIALOG (dialog));
+}
+
+static void
+serialize_child (GString   *str,
+                 int        indent,
+                 GtkWidget *child)
+{
+  const char *name;
+
+  name = gtk_widget_get_name (child);
+  g_string_append_printf (str, "%*s<child>\n", indent, "");
+  g_string_append_printf (str, "%*s  <object class=\"GtkLabel\" id=\"%s\">\n", indent, "", name);
+  g_string_append_printf (str, "%*s    <property name=\"label\">%s</property>\n", indent, "", name);
+  g_string_append_printf (str, "%*s  </object>\n", indent, "");
+  g_string_append_printf (str, "%*s</child>\n", indent, "");
+}
+
+static char *
+serialize_model (GListModel *list)
+{
+  GString *str = g_string_new ("");
+  int i;
+
+  g_string_append (str, "<interface>\n");
+  g_string_append (str, "  <object class=\"GtkBox\" id=\"view\">\n");
+  g_string_append (str, "    <property name=\"layout-manager\">\n");
+  g_string_append (str, "      <object class=\"GtkConstraintLayout\">\n");
+  g_string_append (str, "        <constraints>\n");
+  for (i = 0; i < g_list_model_get_n_items (list); i++)
+    {
+      gpointer item = g_list_model_get_item (list, i);
+      g_object_unref (item);
+      if (GTK_IS_CONSTRAINT (item))
+        constraint_editor_serialize_constraint (str, 10, GTK_CONSTRAINT (item));
+      else if (GTK_IS_CONSTRAINT_GUIDE (item))
+        guide_editor_serialize_guide (str, 10, GTK_CONSTRAINT_GUIDE (item));
+    }
+  g_string_append (str, "        </constraints>\n");
+  g_string_append (str, "      </object>\n");
+  g_string_append (str, "    </property>\n");
+  for (i = 0; i < g_list_model_get_n_items (list); i++)
+    {
+      gpointer item = g_list_model_get_item (list, i);
+      g_object_unref (item);
+      if (GTK_IS_WIDGET (item))
+        serialize_child (str, 4, GTK_WIDGET (item));
+    }
+  g_string_append (str, "  </object>\n");
+  g_string_append (str, "</interface>\n");
+
+  return g_string_free (str, FALSE);
+}
+
+
+static void
+save_response_cb (GtkNativeDialog        *dialog,
+                  gint                    response,
+                  ConstraintEditorWindow *self)
+{
+  gtk_native_dialog_hide (dialog);
+
+  if (response == GTK_RESPONSE_ACCEPT)
+    {
+      GListModel *model;
+      char *text, *filename;
+      GError *error = NULL;
+
+      model = constraint_view_get_model (CONSTRAINT_VIEW (self->view));
+      text = serialize_model (model);
+
+      filename = gtk_file_chooser_get_filename (GTK_FILE_CHOOSER (dialog));
+      if (!g_file_set_contents (filename, text, -1, &error))
+        {
+          GtkWidget *dialog;
+
+          dialog = gtk_message_dialog_new (GTK_WINDOW (gtk_widget_get_root (GTK_WIDGET (self))),
+                                           GTK_DIALOG_MODAL|GTK_DIALOG_DESTROY_WITH_PARENT,
+                                           GTK_MESSAGE_INFO,
+                                           GTK_BUTTONS_OK,
+                                           "Saving failed");
+          gtk_message_dialog_format_secondary_text (GTK_MESSAGE_DIALOG (dialog),
+                                                    "%s", error->message);
+          g_signal_connect (dialog, "response", G_CALLBACK (gtk_widget_destroy), NULL);
+          gtk_widget_show (dialog);
+          g_error_free (error);
+        }
+      g_free (filename);
+    }
+
+  gtk_native_dialog_destroy (dialog);
+}
+
+static void
+save_cb (GtkWidget              *button,
+         ConstraintEditorWindow *self)
+{
+  GtkFileChooserNative *dialog;
+
+  dialog = gtk_file_chooser_native_new ("Save constraints",
+                                        GTK_WINDOW (gtk_widget_get_root (GTK_WIDGET (button))),
+                                        GTK_FILE_CHOOSER_ACTION_SAVE,
+                                        "_Save",
+                                        "_Cancel");
+
+  gtk_native_dialog_set_modal (GTK_NATIVE_DIALOG (dialog), TRUE);
+  gtk_file_chooser_set_current_folder (GTK_FILE_CHOOSER (dialog), ".");
+  g_signal_connect (dialog, "response", G_CALLBACK (save_response_cb), self);
+  gtk_native_dialog_show (GTK_NATIVE_DIALOG (dialog));
+}
+
+static void
+constraint_editor_window_finalize (GObject *object)
+{
+  //ConstraintEditorWindow *self = (ConstraintEditorWindow *)object;
+
+  G_OBJECT_CLASS (constraint_editor_window_parent_class)->finalize (object);
+}
+
+static int child_counter;
+static int guide_counter;
+
+static void
+add_child (ConstraintEditorWindow *win)
+{
+  char *name;
+
+  child_counter++;
+  name = g_strdup_printf ("Child %d", child_counter);
+  constraint_view_add_child (CONSTRAINT_VIEW (win->view), name);
+  g_free (name);
+}
+
+static void
+add_guide (ConstraintEditorWindow *win)
+{
+  char *name;
+  GtkConstraintGuide *guide;
+
+  guide_counter++;
+  name = g_strdup_printf ("Guide %d", guide_counter);
+  guide = gtk_constraint_guide_new ();
+  gtk_constraint_guide_set_name (guide, name);
+  gtk_constraint_guide_set_min_size (guide, 100, 25);
+  g_free (name);
+
+  constraint_view_add_guide (CONSTRAINT_VIEW (win->view), guide);
+}
+
+static void
+constraint_editor_done (ConstraintEditor *editor,
+                        GtkConstraint    *constraint,
+                        ConstraintEditorWindow *win)
+{
+  GtkConstraint *old_constraint;
+
+  g_object_get (editor, "constraint", &old_constraint, NULL);
+
+  if (old_constraint)
+    constraint_view_remove_constraint (CONSTRAINT_VIEW (win->view), old_constraint);
+
+  constraint_view_add_constraint (CONSTRAINT_VIEW (win->view), constraint);
+
+  g_clear_object (&old_constraint);
+
+  gtk_widget_destroy (gtk_widget_get_ancestor (GTK_WIDGET (editor), GTK_TYPE_WINDOW));
+}
+
+static void
+edit_constraint (ConstraintEditorWindow *win,
+                 GtkConstraint          *constraint)
+{
+  GtkWidget *window;
+  ConstraintEditor *editor;
+  GListModel *model;
+
+  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_transient_for (GTK_WINDOW (window), GTK_WINDOW (win));
+  gtk_window_set_resizable (GTK_WINDOW (window), FALSE);
+  if (constraint)
+    gtk_window_set_title (GTK_WINDOW (window), "Edit Constraint");
+  else
+    gtk_window_set_title (GTK_WINDOW (window), "Create Constraint");
+
+  model = constraint_view_get_model (CONSTRAINT_VIEW (win->view));
+
+  editor = constraint_editor_new (model, constraint);
+
+  gtk_container_add (GTK_CONTAINER (window), GTK_WIDGET (editor));
+
+  g_signal_connect (editor, "done", G_CALLBACK (constraint_editor_done), win);
+
+  gtk_widget_show (window);
+}
+
+static void
+add_constraint (ConstraintEditorWindow *win)
+{
+  edit_constraint (win, NULL);
+}
+
+static void
+guide_editor_done (GuideEditor            *editor,
+                   GtkConstraintGuide     *guide,
+                   ConstraintEditorWindow *win)
+{
+  gtk_widget_destroy (gtk_widget_get_ancestor (GTK_WIDGET (editor), GTK_TYPE_WINDOW));
+}
+
+static void
+edit_guide (ConstraintEditorWindow *win,
+            GtkConstraintGuide     *guide)
+{
+  GtkWidget *window;
+  GuideEditor *editor;
+
+  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_resizable (GTK_WINDOW (window), FALSE);
+  gtk_window_set_transient_for (GTK_WINDOW (window), GTK_WINDOW (win));
+  gtk_window_set_title (GTK_WINDOW (window), "Edit Guide");
+
+  editor = guide_editor_new (guide);
+  gtk_container_add (GTK_CONTAINER (window), GTK_WIDGET (editor));
+
+  g_signal_connect (editor, "done", G_CALLBACK (guide_editor_done), win);
+  gtk_widget_show (window);
+}
+
+static void
+child_editor_done (ChildEditor            *editor,
+                   GtkWidget              *child,
+                   ConstraintEditorWindow *win)
+{
+  gtk_widget_destroy (gtk_widget_get_ancestor (GTK_WIDGET (editor), GTK_TYPE_WINDOW));
+}
+
+static void
+edit_child (ConstraintEditorWindow *win,
+            GtkWidget              *child)
+{
+  GtkWidget *window;
+  ChildEditor *editor;
+
+  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_resizable (GTK_WINDOW (window), FALSE);
+  gtk_window_set_transient_for (GTK_WINDOW (window), GTK_WINDOW (win));
+  gtk_window_set_title (GTK_WINDOW (window), "Edit Child");
+
+  editor = child_editor_new (child);
+  gtk_container_add (GTK_CONTAINER (window), GTK_WIDGET (editor));
+
+  g_signal_connect (editor, "done", G_CALLBACK (child_editor_done), win);
+  gtk_widget_show (window);
+}
+
+static void
+row_activated (GtkListBox *list,
+               GtkListBoxRow *row,
+               ConstraintEditorWindow *win)
+{
+  GObject *item;
+
+  item = G_OBJECT (g_object_get_data (G_OBJECT (row), "item"));
+
+  if (GTK_IS_CONSTRAINT (item))
+    edit_constraint (win, GTK_CONSTRAINT (item));
+  else if (GTK_IS_CONSTRAINT_GUIDE (item))
+    edit_guide (win, GTK_CONSTRAINT_GUIDE (item));
+  else if (GTK_IS_WIDGET (item))
+    edit_child (win, GTK_WIDGET (item));
+}
+
+static void
+constraint_editor_window_class_init (ConstraintEditorWindowClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
+
+  g_type_ensure (CONSTRAINT_VIEW_TYPE);
+
+  object_class->finalize = constraint_editor_window_finalize;
+
+  gtk_widget_class_set_template_from_resource (widget_class,
+                                               "/org/gtk/gtk4/constraint-editor/constraint-editor-window.ui");
+
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditorWindow, paned);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditorWindow, view);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditorWindow, list);
+
+  gtk_widget_class_bind_template_callback (widget_class, open_cb);
+  gtk_widget_class_bind_template_callback (widget_class, save_cb);
+  gtk_widget_class_bind_template_callback (widget_class, add_child);
+  gtk_widget_class_bind_template_callback (widget_class, add_guide);
+  gtk_widget_class_bind_template_callback (widget_class, add_constraint);
+  gtk_widget_class_bind_template_callback (widget_class, row_activated);
+}
+
+static void
+row_edit (GtkButton *button,
+          ConstraintEditorWindow *win)
+{
+  GtkWidget *row;
+  GObject *item;
+
+  row = gtk_widget_get_ancestor (GTK_WIDGET (button), GTK_TYPE_LIST_BOX_ROW);
+  item = (GObject *)g_object_get_data (G_OBJECT (row), "item");
+  if (GTK_IS_CONSTRAINT (item))
+    edit_constraint (win, GTK_CONSTRAINT (item));
+  else if (GTK_IS_CONSTRAINT_GUIDE (item))
+    edit_guide (win, GTK_CONSTRAINT_GUIDE (item));
+  else if (GTK_IS_WIDGET (item))
+    edit_child (win, GTK_WIDGET (item));
+}
+
+static void
+mark_constraints_invalid (ConstraintEditorWindow *win,
+                          gpointer                removed)
+{
+  GtkWidget *child;
+  GObject *item;
+
+  for (child = gtk_widget_get_first_child (win->list);
+       child;
+       child = gtk_widget_get_next_sibling (child))
+    {
+      item = (GObject *)g_object_get_data (G_OBJECT (child), "item");
+      if (GTK_IS_CONSTRAINT (item))
+        {
+          GtkConstraint *constraint = GTK_CONSTRAINT (item);
+
+          if (gtk_constraint_get_target (constraint) == (GtkConstraintTarget *)removed ||
+              gtk_constraint_get_source (constraint) == (GtkConstraintTarget *)removed)
+            {
+              GtkWidget *button;
+              button = (GtkWidget *)g_object_get_data (G_OBJECT (child), "edit");
+              gtk_button_set_icon_name (GTK_BUTTON (button), "dialog-warning-symbolic");
+              gtk_widget_set_tooltip_text (button, "Constraint is invalid");
+            }
+        }
+    }
+}
+
+static void
+row_delete (GtkButton *button,
+            ConstraintEditorWindow *win)
+{
+  GtkWidget *row;
+  GObject *item;
+
+  row = gtk_widget_get_ancestor (GTK_WIDGET (button), GTK_TYPE_LIST_BOX_ROW);
+  item = (GObject *)g_object_get_data (G_OBJECT (row), "item");
+  if (GTK_IS_CONSTRAINT (item))
+    constraint_view_remove_constraint (CONSTRAINT_VIEW (win->view),
+                                       GTK_CONSTRAINT (item));
+  else if (GTK_IS_CONSTRAINT_GUIDE (item))
+    {
+      mark_constraints_invalid (win, item);
+      constraint_view_remove_guide (CONSTRAINT_VIEW (win->view),
+                                    GTK_CONSTRAINT_GUIDE (item));
+    }
+  else if (GTK_IS_WIDGET (item))
+    {
+      mark_constraints_invalid (win, item);
+      constraint_view_remove_child (CONSTRAINT_VIEW (win->view),
+                                    GTK_WIDGET (item));
+    }
+}
+
+static GtkWidget *
+create_widget_func (gpointer item,
+                    gpointer user_data)
+{
+  ConstraintEditorWindow *win = user_data;
+  const char *name;
+  char *freeme = NULL;
+  GtkWidget *row, *box, *label, *button;
+
+  if (GTK_IS_WIDGET (item))
+    name = gtk_widget_get_name (GTK_WIDGET (item));
+  else if (GTK_IS_CONSTRAINT_GUIDE (item))
+    name = gtk_constraint_guide_get_name (GTK_CONSTRAINT_GUIDE (item));
+  else if (GTK_IS_CONSTRAINT (item))
+    name = freeme = constraint_editor_constraint_to_string (GTK_CONSTRAINT (item));
+  else
+    name = "";
+
+  row = gtk_list_box_row_new ();
+  g_object_set_data_full (G_OBJECT (row), "item", g_object_ref (item), g_object_unref);
+  box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
+  label = gtk_label_new (name);
+  if (GTK_IS_WIDGET (item) || GTK_IS_CONSTRAINT_GUIDE (item))
+    g_object_bind_property (item, "name",
+                            label, "label",
+                            G_BINDING_DEFAULT);
+  g_object_set (label, "margin", 10, NULL);
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_widget_set_hexpand (label, TRUE);
+  gtk_container_add (GTK_CONTAINER (row), box);
+  gtk_container_add (GTK_CONTAINER (box), label);
+
+  button = gtk_button_new_from_icon_name ("document-edit-symbolic");
+  gtk_button_set_relief (GTK_BUTTON (button), GTK_RELIEF_NONE);
+  g_signal_connect (button, "clicked", G_CALLBACK (row_edit), win);
+  g_object_set_data (G_OBJECT (row), "edit", button);
+  gtk_container_add (GTK_CONTAINER (box), button);
+  button = gtk_button_new_from_icon_name ("edit-delete-symbolic");
+  gtk_button_set_relief (GTK_BUTTON (button), GTK_RELIEF_NONE);
+  g_signal_connect (button, "clicked", G_CALLBACK (row_delete), win);
+  gtk_container_add (GTK_CONTAINER (box), button);
+
+  g_free (freeme);
+
+  return row;
+}
+
+static void
+constraint_editor_window_init (ConstraintEditorWindow *self)
+{
+  gtk_widget_init_template (GTK_WIDGET (self));
+
+  gtk_list_box_bind_model (GTK_LIST_BOX (self->list),
+                           constraint_view_get_model (CONSTRAINT_VIEW (self->view)),
+                           create_widget_func,
+                           self,
+                           NULL);
+}
+
+ConstraintEditorWindow *
+constraint_editor_window_new (ConstraintEditorApplication *application)
+{
+  return g_object_new (CONSTRAINT_EDITOR_WINDOW_TYPE,
+                       "application", application,
+                       NULL);
+}
@@ -0,0 +1,34 @@
+/*
+ * Copyright © 2019 Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+#include "constraint-editor-application.h"
+
+
+#define CONSTRAINT_EDITOR_WINDOW_TYPE (constraint_editor_window_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintEditorWindow, constraint_editor_window, CONSTRAINT, EDITOR_WINDOW, GtkApplicationWindow)
+
+ConstraintEditorWindow * constraint_editor_window_new  (ConstraintEditorApplication  *application);
+
+gboolean                 constraint_editor_window_load (ConstraintEditorWindow       *self,
+                                                        GFile                        *file);
@@ -0,0 +1,82 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <template class="ConstraintEditorWindow" parent="GtkApplicationWindow">
+    <style>
+      <class name="devel"/>
+    </style>
+    <property name="title" translatable="yes">GTK Constraint Editor</property>
+    <property name="default-width">1024</property>
+    <property name="default-height">768</property>
+    <child type="titlebar">
+      <object class="GtkHeaderBar" id="header">
+        <property name="title" translatable="yes">GTK Constraint Editor</property>
+        <property name="show-title-buttons">1</property>
+        <child type="start">
+          <object class="GtkButton">
+            <property name="icon-name">document-open-symbolic</property>
+            <property name="tooltip-text">Open ui file</property>
+            <signal name="clicked" handler="open_cb"/>
+          </object>
+        </child>
+        <child type="start">
+          <object class="GtkButton">
+            <property name="icon-name">document-save-symbolic</property>
+            <property name="tooltip-text">Save to ui file</property>
+            <signal name="clicked" handler="save_cb"/>
+          </object>
+        </child>
+      </object>
+    </child>
+    <child>
+      <object class="GtkPaned" id="paned">
+        <property name="orientation">horizontal</property>
+        <child>
+          <object class="GtkBox">
+            <property name="orientation">vertical</property>
+            <child>
+              <object class="GtkBox">
+                <property name="orientation">horizontal</property>
+                <child>
+                  <object class="GtkButton">
+                    <property name="label">Add Child</property>
+                    <signal name="clicked" handler="add_child" swapped="yes"/>
+                  </object>
+                </child>
+                <child>
+                  <object class="GtkButton">
+                    <property name="label">Add Guide</property>
+                    <signal name="clicked" handler="add_guide" swapped="yes"/>
+                  </object>
+                </child>
+                <child>
+                  <object class="GtkButton">
+                    <property name="label">Add Constraint</property>
+                    <signal name="clicked" handler="add_constraint" swapped="yes"/>
+                  </object>
+                </child>
+              </object>
+            </child>
+            <child>
+              <object class="GtkScrolledWindow">
+                <property name="hscrollbar-policy">never</property>
+                <property name="vscrollbar-policy">automatic</property>
+                <property name="vexpand">1</property>
+                <child>
+                  <object class="GtkListBox" id="list">
+                    <property name="show-separators">1</property>
+                    <property name="selection-mode">none</property>
+                    <signal name="row-activated" handler="row_activated"/>
+                  </object>
+                </child>
+              </object>
+            </child>
+          </object>
+        </child>
+        <child>
+          <object class="ConstraintView" id="view">
+          </object>
+        </child>
+      </object>
+    </child>
+  </template>
+</interface>
@@ -0,0 +1,682 @@
+/*
+ * Copyright © 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#include "config.h"
+
+#include "constraint-editor.h"
+
+struct _ConstraintEditor
+{
+  GtkWidget parent_instance;
+
+  GtkWidget *grid;
+  GtkWidget *target;
+  GtkWidget *target_attr;
+  GtkWidget *relation;
+  GtkWidget *source;
+  GtkWidget *source_attr;
+  GtkWidget *multiplier;
+  GtkWidget *constant;
+  GtkWidget *strength;
+  GtkWidget *preview;
+  GtkWidget *button;
+
+  GtkConstraint *constraint;
+  GListModel *model;
+
+  gboolean constructed;
+};
+
+enum {
+  PROP_MODEL = 1,
+  PROP_CONSTRAINT,
+  LAST_PROP
+};
+
+static GParamSpec *pspecs[LAST_PROP];
+
+enum {
+  DONE,
+  LAST_SIGNAL
+};
+
+static guint signals[LAST_SIGNAL];
+
+G_DEFINE_TYPE(ConstraintEditor, constraint_editor, GTK_TYPE_WIDGET);
+
+static const char *
+get_target_name (GtkConstraintTarget *target)
+{
+  if (target == NULL)
+    return "super";
+  else if (GTK_IS_WIDGET (target))
+    return gtk_widget_get_name (GTK_WIDGET (target));
+  else if (GTK_IS_CONSTRAINT_GUIDE (target))
+    return gtk_constraint_guide_get_name (GTK_CONSTRAINT_GUIDE (target));
+  else
+    return "";
+}
+
+static void
+constraint_target_combo (GListModel *model,
+                         GtkWidget  *combo,
+                         gboolean    is_source)
+{
+  int i;
+
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "super", "Super");
+
+  if (model)
+    {
+      for (i = 0; i < g_list_model_get_n_items (model); i++)
+        {
+          GObject *item = g_list_model_get_object (model, i);
+          const char *name;
+
+          if (GTK_IS_CONSTRAINT (item))
+            continue;
+
+          name = get_target_name (GTK_CONSTRAINT_TARGET (item));
+
+          gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), name, name);
+          g_object_unref (item);
+        }
+    }
+}
+
+static void
+constraint_attribute_combo (GtkWidget *combo,
+                            gboolean is_source)
+{
+  if (is_source)
+    gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "none", "None");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "left", "Left");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "right", "Right");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "top", "Top");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "bottom", "Bottom");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "start", "Start");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "end", "End");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "width", "Width");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "height", "Height");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "center-x", "Center X");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "center-y", "Center Y");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "baseline", "Baseline");
+}
+
+static void
+constraint_relation_combo (GtkWidget *combo)
+{
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "le", "≤");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "eq", "=");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "ge", "≥");
+}
+
+static void
+constraint_strength_combo (GtkWidget *combo)
+{
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "weak", "Weak");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "medium", "Medium");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "strong", "Strong");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "required", "Required");
+}
+
+static gpointer
+get_target (GListModel *model,
+            const char *id)
+{
+  int i;
+
+  if (strcmp ("super", id) == 0)
+    return NULL;
+
+  for (i = 0; i < g_list_model_get_n_items (model); i++)
+    {
+      GObject *item = g_list_model_get_object (model, i);
+      g_object_unref (item);
+      if (GTK_IS_CONSTRAINT (item))
+        continue;
+      else if (GTK_IS_WIDGET (item))
+        {
+          if (strcmp (id, gtk_widget_get_name (GTK_WIDGET (item))) == 0)
+            return item;
+        }
+      else if (GTK_IS_CONSTRAINT_GUIDE (item))
+        {
+          if (strcmp (id, gtk_constraint_guide_get_name (GTK_CONSTRAINT_GUIDE (item))) == 0)
+            return item;
+        }
+    }
+
+  return NULL;
+}
+
+static GtkConstraintAttribute
+get_target_attr (const char *id)
+{
+  GtkConstraintAttribute attr;
+  GEnumClass *class = g_type_class_ref (GTK_TYPE_CONSTRAINT_ATTRIBUTE);
+  GEnumValue *value = g_enum_get_value_by_nick (class, id);
+  attr = value->value;
+  g_type_class_unref (class);
+
+  return attr;
+}
+
+static const char *
+get_attr_nick (GtkConstraintAttribute attr)
+{
+  GEnumClass *class = g_type_class_ref (GTK_TYPE_CONSTRAINT_ATTRIBUTE);
+  GEnumValue *value = g_enum_get_value (class, attr);
+  const char *nick = value->value_nick;
+  g_type_class_unref (class);
+
+  return nick;
+}
+
+static GtkConstraintRelation
+get_relation (const char *id)
+{
+  GtkConstraintRelation relation;
+  GEnumClass *class = g_type_class_ref (GTK_TYPE_CONSTRAINT_RELATION);
+  GEnumValue *value = g_enum_get_value_by_nick (class, id);
+  relation = value->value;
+  g_type_class_unref (class);
+
+  return relation;
+}
+
+static const char *
+get_relation_nick (GtkConstraintRelation relation)
+{
+  GEnumClass *class = g_type_class_ref (GTK_TYPE_CONSTRAINT_RELATION);
+  GEnumValue *value = g_enum_get_value (class, relation);
+  const char *nick = value->value_nick;
+  g_type_class_unref (class);
+
+  return nick;
+}
+
+static const char *
+get_relation_to_string (GtkConstraintRelation relation)
+{
+  switch (relation)
+    {
+    case GTK_CONSTRAINT_RELATION_LE: return "≤";
+    case GTK_CONSTRAINT_RELATION_EQ: return "=";
+    case GTK_CONSTRAINT_RELATION_GE: return "≥";
+    default:
+      g_assert_not_reached ();
+    }
+}
+
+static GtkConstraintStrength
+get_strength (const char *id)
+{
+  GtkConstraintStrength strength;
+  GEnumClass *class = g_type_class_ref (GTK_TYPE_CONSTRAINT_STRENGTH);
+  GEnumValue *value = g_enum_get_value_by_nick (class, id);
+  strength = value->value;
+  g_type_class_unref (class);
+
+  return strength;
+}
+
+static const char *
+get_strength_nick (GtkConstraintStrength strength)
+{
+  GEnumClass *class = g_type_class_ref (GTK_TYPE_CONSTRAINT_STRENGTH);
+  GEnumValue *value = g_enum_get_value (class, strength);
+  const char *nick = value->value_nick;
+  g_type_class_unref (class);
+
+  return nick;
+}
+
+void
+constraint_editor_serialize_constraint (GString       *str,
+                                        int            indent,
+                                        GtkConstraint *constraint)
+{
+  const char *target;
+  const char *target_attr;
+  const char *relation;
+  const char *source;
+  const char *source_attr;
+  double multiplier;
+  double constant;
+  const char *strength;
+
+  target = get_target_name (gtk_constraint_get_target (constraint));
+  target_attr = get_attr_nick (gtk_constraint_get_target_attribute (constraint));
+  relation = get_relation_nick (gtk_constraint_get_relation (constraint));
+  source = get_target_name (gtk_constraint_get_source (constraint));
+  source_attr = get_attr_nick (gtk_constraint_get_source_attribute (constraint));
+  multiplier = gtk_constraint_get_multiplier (constraint);
+  constant = gtk_constraint_get_constant (constraint);
+  strength = get_strength_nick (gtk_constraint_get_strength (constraint));
+
+  g_string_append_printf (str, "%*s<constraint target=\"%s\" target-attribute=\"%s\"\n", indent, "", target, target_attr);
+  g_string_append_printf (str, "%*s            relation=\"%s\"\n", indent, "", relation);
+  if (strcmp (source_attr, "none") != 0)
+    {
+      g_string_append_printf (str, "%*s            source=\"%s\" source-attribute=\"%s\"\n", indent, "", source, source_attr);
+      g_string_append_printf (str, "%*s            multiplier=\"%g\"\n", indent, "", multiplier);
+    }
+  g_string_append_printf (str, "%*s            constant=\"%g\"\n", indent, "", constant);
+  g_string_append_printf (str, "%*s            strength=\"%s\" />\n", indent, "", strength);
+}
+
+static void
+create_constraint (GtkButton        *button,
+                   ConstraintEditor *editor)
+{
+  const char *id;
+  gpointer target;
+  GtkConstraintAttribute target_attr;
+  gpointer source;
+  GtkConstraintAttribute source_attr;
+  GtkConstraintRelation relation;
+  double multiplier;
+  double constant;
+  int strength;
+  GtkConstraint *constraint;
+
+  id = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->target));
+  target = get_target (editor->model, id);
+  id = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->target_attr));
+  target_attr = get_target_attr (id);
+
+  id = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->source));
+  if (id != NULL)
+    {
+      source = get_target (editor->model, id);
+      id = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->source_attr));
+      source_attr = get_target_attr (id);
+    }
+  else
+    {
+      source = NULL;
+      source_attr = GTK_CONSTRAINT_ATTRIBUTE_NONE;
+    }
+
+  id = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->relation));
+  relation = get_relation (id);
+
+  multiplier = g_ascii_strtod (gtk_editable_get_text (GTK_EDITABLE (editor->multiplier)), NULL);
+
+  constant = g_ascii_strtod (gtk_editable_get_text (GTK_EDITABLE (editor->constant)), NULL);
+
+  id = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->strength));
+  strength = get_strength (id);
+
+  constraint = gtk_constraint_new (target, target_attr,
+                                   relation,
+                                   source, source_attr,
+                                   multiplier,
+                                   constant,
+                                   strength);
+  g_signal_emit (editor, signals[DONE], 0, constraint);
+  g_object_unref (constraint);
+}
+
+static void
+source_attr_changed (ConstraintEditor *editor)
+{
+  const char *id;
+
+  id = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->source_attr));
+  if (strcmp (id, "none") == 0)
+    {
+      gtk_combo_box_set_active (GTK_COMBO_BOX (editor->source), -1);
+      gtk_editable_set_text (GTK_EDITABLE (editor->multiplier), "");
+      gtk_widget_set_sensitive (editor->source, FALSE);
+      gtk_widget_set_sensitive (editor->multiplier, FALSE);
+    }
+  else
+    {
+      gtk_widget_set_sensitive (editor->source, TRUE);
+      gtk_widget_set_sensitive (editor->multiplier, TRUE);
+    }
+}
+
+char *
+constraint_editor_constraint_to_string (GtkConstraint *constraint)
+{
+  GString *str;
+  const char *name;
+  const char *attr;
+  const char *relation;
+  double c, m;
+
+  str = g_string_new ("");
+
+  name = get_target_name (gtk_constraint_get_target (constraint));
+  attr = get_attr_nick (gtk_constraint_get_target_attribute (constraint));
+  relation = get_relation_to_string (gtk_constraint_get_relation (constraint));
+
+  if (name == NULL)
+    name = "[ ]";
+
+  g_string_append_printf (str, "%s.%s %s ", name, attr, relation);
+
+  c = gtk_constraint_get_constant (constraint);
+
+  attr = get_attr_nick (gtk_constraint_get_source_attribute (constraint));
+  if (strcmp (attr, "none") != 0)
+    {
+      name = get_target_name (gtk_constraint_get_source (constraint));
+      m = gtk_constraint_get_multiplier (constraint);
+
+      if (name == NULL)
+        name = "[ ]";
+
+      g_string_append_printf (str, "%s.%s", name, attr);
+
+      if (m != 1.0)
+        g_string_append_printf (str, " × %g", m);
+
+      if (c > 0.0)
+        g_string_append_printf (str, " + %g", c);
+      else if (c < 0.0)
+        g_string_append_printf (str, " - %g", -c);
+    }
+  else
+    g_string_append_printf (str, "%g", c);
+
+  return g_string_free (str, FALSE);
+}
+
+static void
+update_preview (ConstraintEditor *editor)
+{
+  GString *str;
+  const char *name;
+  const char *attr;
+  char *relation;
+  const char *multiplier;
+  const char *constant;
+  double c, m;
+
+  if (!editor->constructed)
+    return;
+
+  str = g_string_new ("");
+
+  name = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->target));
+  attr = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->target_attr));
+  relation = gtk_combo_box_text_get_active_text (GTK_COMBO_BOX_TEXT (editor->relation));
+
+  if (name == NULL)
+    name = "[ ]";
+
+  g_string_append_printf (str, "%s.%s %s ", name, attr, relation);
+  g_free (relation);
+
+  constant = gtk_editable_get_text (GTK_EDITABLE (editor->constant));
+  if (constant[0] != '\0')
+    c = g_ascii_strtod (constant, NULL);
+  else
+    c = 0.0;
+
+  attr = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->source_attr));
+  if (strcmp (attr, "none") != 0)
+    {
+      name = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->source));
+      multiplier = gtk_editable_get_text (GTK_EDITABLE (editor->multiplier));
+      if (multiplier[0] != '\0')
+        m = g_ascii_strtod (multiplier, NULL);
+      else
+        m = 1.0;
+
+      if (name == NULL)
+        name = "[ ]";
+
+      g_string_append_printf (str, "%s.%s", name, attr);
+
+      if (m != 1.0)
+        g_string_append_printf (str, " × %g", m);
+
+      if (c > 0.0)
+        g_string_append_printf (str, " + %g", c);
+      else if (c < 0.0)
+        g_string_append_printf (str, " - %g", -c);
+    }
+  else
+    g_string_append_printf (str, "%g", c);
+
+  gtk_label_set_label (GTK_LABEL (editor->preview), str->str);
+
+  g_string_free (str, TRUE);
+}
+
+static void
+update_button (ConstraintEditor *editor)
+{
+  if (gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->target)) != NULL)
+    gtk_widget_set_sensitive (editor->button, TRUE);
+  else
+    gtk_widget_set_sensitive (editor->button, FALSE);
+}
+
+static void
+constraint_editor_init (ConstraintEditor *editor)
+{
+  gtk_widget_init_template (GTK_WIDGET (editor));
+}
+
+static void
+constraint_editor_constructed (GObject *object)
+{
+  ConstraintEditor *editor = CONSTRAINT_EDITOR (object);
+
+  constraint_target_combo (editor->model, editor->target, FALSE);
+  constraint_attribute_combo (editor->target_attr, FALSE);
+  constraint_relation_combo (editor->relation);
+  constraint_target_combo (editor->model, editor->source, TRUE);
+  constraint_attribute_combo (editor->source_attr, TRUE);
+
+  constraint_strength_combo (editor->strength);
+
+  if (editor->constraint)
+    {
+      GtkConstraintTarget *target;
+      GtkConstraintAttribute attr;
+      GtkConstraintRelation relation;
+      GtkConstraintStrength strength;
+      const char *nick;
+      char *val;
+      double multiplier;
+      double constant;
+
+      target = gtk_constraint_get_target (editor->constraint);
+      nick = get_target_name (target);
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->target), nick);
+
+      attr = gtk_constraint_get_target_attribute (editor->constraint);
+      nick = get_attr_nick (attr);
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->target_attr), nick);
+
+      target = gtk_constraint_get_source (editor->constraint);
+      nick = get_target_name (target);
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->source), nick);
+
+      attr = gtk_constraint_get_source_attribute (editor->constraint);
+      nick = get_attr_nick (attr);
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->source_attr), nick);
+
+      relation = gtk_constraint_get_relation (editor->constraint);
+      nick = get_relation_nick (relation);
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->relation), nick);
+
+      multiplier = gtk_constraint_get_multiplier (editor->constraint);
+      val = g_strdup_printf ("%g", multiplier);
+      gtk_editable_set_text (GTK_EDITABLE (editor->multiplier), val);
+      g_free (val);
+
+      constant = gtk_constraint_get_constant (editor->constraint);
+      val = g_strdup_printf ("%g", constant);
+      gtk_editable_set_text (GTK_EDITABLE (editor->constant), val);
+      g_free (val);
+
+      strength = gtk_constraint_get_strength (editor->constraint);
+      nick = get_strength_nick (strength);
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->strength), nick);
+
+      gtk_button_set_label (GTK_BUTTON (editor->button), "Apply");
+    }
+  else
+    {
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->target_attr), "left");
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->source_attr), "left");
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->relation), "eq");
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->strength), "required");
+
+      gtk_editable_set_text (GTK_EDITABLE (editor->multiplier), "1.0");
+      gtk_editable_set_text (GTK_EDITABLE (editor->constant), "0.0");
+
+      gtk_button_set_label (GTK_BUTTON (editor->button), "Create");
+    }
+
+  editor->constructed = TRUE;
+  update_preview (editor);
+  update_button (editor);
+}
+
+static void
+constraint_editor_set_property (GObject      *object,
+                                guint         property_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  ConstraintEditor *self = CONSTRAINT_EDITOR (object);
+
+  switch (property_id)
+    {
+    case PROP_MODEL:
+      self->model = g_value_dup_object (value);
+      break;
+
+    case PROP_CONSTRAINT:
+      self->constraint = g_value_dup_object (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+    }
+}
+
+static void
+constraint_editor_get_property (GObject    *object,
+                                guint       property_id,
+                                GValue     *value,
+                                GParamSpec *pspec)
+{
+  ConstraintEditor *self = CONSTRAINT_EDITOR (object);
+
+  switch (property_id)
+    {
+    case PROP_MODEL:
+      g_value_set_object (value, self->model);
+      break;
+
+    case PROP_CONSTRAINT:
+      g_value_set_object (value, self->constraint);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+    }
+}
+
+static void
+constraint_editor_dispose (GObject *object)
+{
+  ConstraintEditor *self = (ConstraintEditor *)object;
+
+  g_clear_pointer (&self->grid, gtk_widget_unparent);
+  g_clear_object (&self->model);
+  g_clear_object (&self->constraint);
+
+  G_OBJECT_CLASS (constraint_editor_parent_class)->dispose (object);
+}
+
+static void
+constraint_editor_class_init (ConstraintEditorClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
+
+  object_class->constructed = constraint_editor_constructed;
+  object_class->dispose = constraint_editor_dispose;
+  object_class->set_property = constraint_editor_set_property;
+  object_class->get_property = constraint_editor_get_property;
+
+  pspecs[PROP_CONSTRAINT] =
+    g_param_spec_object ("constraint", "constraint", "constraint",
+                         GTK_TYPE_CONSTRAINT,
+                         G_PARAM_READWRITE|G_PARAM_CONSTRUCT_ONLY);
+
+  pspecs[PROP_MODEL] =
+    g_param_spec_object ("model", "model", "model",
+                         G_TYPE_LIST_MODEL,
+                         G_PARAM_READWRITE|G_PARAM_CONSTRUCT_ONLY);
+
+  g_object_class_install_properties (object_class, LAST_PROP, pspecs);
+
+  signals[DONE] =
+    g_signal_new ("done",
+                  G_TYPE_FROM_CLASS (object_class),
+                  G_SIGNAL_RUN_LAST,
+                  0,
+                  NULL, NULL,
+                  NULL,
+                  G_TYPE_NONE, 1, GTK_TYPE_CONSTRAINT);
+
+  gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_BIN_LAYOUT);
+
+  gtk_widget_class_set_template_from_resource (widget_class,
+                                               "/org/gtk/gtk4/constraint-editor/constraint-editor.ui");
+
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, grid);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, target);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, target_attr);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, relation);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, source);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, source_attr);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, multiplier);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, constant);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, strength);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, preview);
+  gtk_widget_class_bind_template_child (widget_class, ConstraintEditor, button);
+
+  gtk_widget_class_bind_template_callback (widget_class, update_preview);
+  gtk_widget_class_bind_template_callback (widget_class, update_button);
+  gtk_widget_class_bind_template_callback (widget_class, create_constraint);
+  gtk_widget_class_bind_template_callback (widget_class, source_attr_changed);
+}
+
+ConstraintEditor *
+constraint_editor_new (GListModel    *model,
+                       GtkConstraint *constraint)
+{
+  return g_object_new (CONSTRAINT_EDITOR_TYPE,
+                       "model", model,
+                       "constraint", constraint,
+                       NULL);
+}
@@ -0,0 +1,13 @@
+constraintview {
+  background: black;
+  color: white;
+}
+
+constraintview .child {
+  background: red;
+}
+
+constraintview guide {
+  background: blue;
+  border: 1px solid white;
+}
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<gresources>
+  <gresource prefix="/org/gtk/gtk4/constraint-editor">
+    <file preprocess="xml-stripblanks">constraint-editor-window.ui</file>
+    <file preprocess="xml-stripblanks">constraint-editor.ui</file>
+    <file preprocess="xml-stripblanks">guide-editor.ui</file>
+    <file preprocess="xml-stripblanks">child-editor.ui</file>
+    <file>constraint-editor.css</file>
+  </gresource>
+</gresources>
@@ -0,0 +1,34 @@
+/*
+ * Copyright © 2019 Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+#define CONSTRAINT_EDITOR_TYPE (constraint_editor_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintEditor, constraint_editor, CONSTRAINT, EDITOR, GtkWidget)
+
+ConstraintEditor * constraint_editor_new (GListModel    *model,
+                                          GtkConstraint *constraint);
+
+void constraint_editor_serialize_constraint (GString       *str,
+                                             int            indent,
+                                             GtkConstraint *constraint);
+char *constraint_editor_constraint_to_string (GtkConstraint *constraint);
@@ -0,0 +1,163 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <template class="ConstraintEditor" parent="GtkWidget">
+    <child>
+      <object class="GtkGrid" id="grid">
+        <property name="margin">20</property>
+        <property name="row-spacing">10</property>
+        <property name="column-spacing">10</property>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Target</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkComboBoxText" id="target">
+            <signal name="changed" handler="update_preview" swapped="yes"/>
+            <signal name="changed" handler="update_button" swapped="yes"/>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkComboBoxText" id="target_attr">
+            <signal name="changed" handler="update_preview" swapped="yes"/>
+            <layout>
+              <property name="left-attach">2</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Relation</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">2</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkComboBoxText" id="relation">
+            <signal name="changed" handler="update_preview" swapped="yes"/>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">2</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Source</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">3</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkComboBoxText" id="source">
+            <signal name="changed" handler="update_preview" swapped="yes"/>
+            <signal name="changed" handler="update_button" swapped="yes"/>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">3</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkComboBoxText" id="source_attr">
+            <signal name="changed" handler="update_preview" swapped="yes"/>
+            <signal name="changed" handler="source_attr_changed" swapped="yes"/>
+            <layout>
+              <property name="left-attach">2</property>
+              <property name="top-attach">3</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Multiplier</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">4</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkEntry" id="multiplier">
+            <signal name="changed" handler="update_preview" swapped="yes"/>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">4</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Constant</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">5</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkEntry" id="constant">
+            <signal name="changed" handler="update_preview" swapped="yes"/>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">5</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Strength</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">6</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkComboBoxText" id="strength">
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">6</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel" id="preview">
+            <property name="xalign">0</property>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">7</property>
+              <property name="column-span">2</property>
+            </layout>
+            <attributes>
+              <attribute name="scale" value="1.44"/>
+            </attributes>
+          </object>
+        </child>
+        <child>
+          <object class="GtkButton" id="button">
+            <property name="label">Create</property>
+            <signal name="clicked" handler="create_constraint"/>
+            <layout>
+              <property name="left-attach">2</property>
+              <property name="top-attach">8</property>
+            </layout>
+          </object>
+        </child>
+      </object>
+    </child>
+  </template>
+</interface>
@@ -0,0 +1,93 @@
+/*
+ * Copyright © 2019 Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#include "constraint-view-child.h"
+
+struct _ConstraintViewChild
+{
+  GObject parent_instance;
+
+  char *name;
+};
+
+enum {
+  PROP_NAME = 1,
+  LAST_PROP
+};
+
+static GParamSpec props[LAST_PROP];
+
+G_DEFINE_TYPE (ConstraintViewChild, constraint_view_child, G_TYPE_OBJECT)
+
+static void
+constraint_view_child_init (ConstraintViewChild *child)
+{
+}
+
+static void
+constraint_view_child_finalize (GObject *object)
+{
+  ConstraintViewChild *child = CONSTRAINT_VIEW_CHILD (object);
+
+  g_free (child->name);
+
+  G_OBJECT_CLASS (constraint_view_child_parent_class)->finalize (object);
+}
+
+static void
+constraint_view_child_set_property (GObject *object,
+                                    
+static void
+constraint_view_child_class_init (ConstraintViewChildClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+
+  object_class->finalize = constraint_view_child_finalize;
+  object_class->get_property = constraint_view_child_get_property;
+  object_class->set_property = constraint_view_child_set_property;
+
+  props[PROP_NAME] =
+    g_param_spec_string ("name", "name", "name",
+                         NULL,
+                         G_PARAM_READWRITE);
+
+  g_object_class_install_properties (object_class, LAST_PROP, props);
+}
+
+#define CONSTRAINT_VIEW_CHILD_TYPE (constraint_view_get_type ())
+
+G_DECLARE_TYPE (ConstraintViewChild, constraint_view_child, CONSTRAINT, VIEW_CHILD, GObject)
+
+#define CONSTRAINT_VIEW_WIDGET_TYPE (constraint_view_widget_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintViewWidget, constraint_view_widget, CONSTRAINT, VIEW_WIDGET, ConstraintViewChild)
+
+ConstraintViewWidget * constraint_view_widget_new (void);
+
+#define CONSTRAINT_VIEW_GUIDE_TYPE (constraint_view_guide_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintViewGuide, constraint_view_guide, CONSTRAINT, VIEW_GUIDE, ConstraintViewChild)
+
+ConstraintViewGuide * constraint_view_guide_new (void);
+
+#define CONSTRAINT_VIEW_CONSTRAINT_TYPE (constraint_view_constraint_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintViewConstraint, constraint_view_constraint, CONSTRAINT, VIEW_CONSTRAINT, ConstraintViewChild)
+
+ConstraintViewGuide * constraint_view_constraint_new (void);
@@ -0,0 +1,44 @@
+/*
+ * Copyright © 2019 Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+#define CONSTRAINT_VIEW_CHILD_TYPE (constraint_view_get_type ())
+
+G_DECLARE_TYPE (ConstraintViewChild, constraint_view_child, CONSTRAINT, VIEW_CHILD, GObject)
+
+#define CONSTRAINT_VIEW_WIDGET_TYPE (constraint_view_widget_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintViewWidget, constraint_view_widget, CONSTRAINT, VIEW_WIDGET, ConstraintViewChild)
+
+ConstraintViewWidget * constraint_view_widget_new (void);
+
+#define CONSTRAINT_VIEW_GUIDE_TYPE (constraint_view_guide_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintViewGuide, constraint_view_guide, CONSTRAINT, VIEW_GUIDE, ConstraintViewChild)
+
+ConstraintViewGuide * constraint_view_guide_new (void);
+
+#define CONSTRAINT_VIEW_CONSTRAINT_TYPE (constraint_view_constraint_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintViewConstraint, constraint_view_constraint, CONSTRAINT, VIEW_CONSTRAINT, ConstraintViewChild)
+
+ConstraintViewGuide * constraint_view_constraint_new (void);
@@ -0,0 +1,350 @@
+/* Copyright (C) 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <gtk/gtk.h>
+#include "constraint-view.h"
+#include "guide-placeholder.h"
+
+struct _ConstraintView
+{
+  GtkWidget parent;
+
+  GListModel *model;
+
+  GtkWidget *drag_widget;
+};
+
+G_DEFINE_TYPE (ConstraintView, constraint_view, GTK_TYPE_WIDGET);
+
+static void
+constraint_view_dispose (GObject *object)
+{
+  ConstraintView *view = CONSTRAINT_VIEW (object);
+  GtkWidget *child;
+
+  while ((child = gtk_widget_get_first_child (GTK_WIDGET (view))) != NULL)
+    gtk_widget_unparent (child);
+
+  g_clear_object (&view->model);
+
+  G_OBJECT_CLASS (constraint_view_parent_class)->dispose (object);
+}
+
+static void
+constraint_view_class_init (ConstraintViewClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  object_class->dispose = constraint_view_dispose;
+
+  gtk_widget_class_set_css_name (widget_class, "constraintview");
+}
+
+static void
+update_weak_position (ConstraintView *self,
+                      GtkWidget      *child,
+                      double          x,
+                      double          y)
+{
+  GtkLayoutManager *manager;
+  GtkConstraint *constraint;
+
+  manager = gtk_widget_get_layout_manager (GTK_WIDGET (self));
+  constraint = (GtkConstraint *)g_object_get_data (G_OBJECT (child), "x-constraint");
+  if (constraint)
+    {
+      gtk_constraint_layout_remove_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                               constraint);
+      g_object_set_data (G_OBJECT (child), "x-constraint", NULL);
+    }
+  if (x != -100)
+    {
+      constraint = gtk_constraint_new_constant (child,
+                                                GTK_CONSTRAINT_ATTRIBUTE_CENTER_X,
+                                                GTK_CONSTRAINT_RELATION_EQ,
+                                                x,
+                                                GTK_CONSTRAINT_STRENGTH_WEAK);
+      g_object_set_data (G_OBJECT (constraint), "internal", "yes");
+      gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                            constraint);
+      g_object_set_data (G_OBJECT (child), "x-constraint", constraint);
+    }
+
+  constraint = (GtkConstraint *)g_object_get_data (G_OBJECT (child), "y-constraint");
+  if (constraint)
+    {
+      gtk_constraint_layout_remove_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                                   constraint);
+      g_object_set_data (G_OBJECT (child), "y-constraint", NULL);
+    }
+  if (y != -100)
+    {
+      constraint = gtk_constraint_new_constant (child,
+                                                GTK_CONSTRAINT_ATTRIBUTE_CENTER_Y,
+                                                GTK_CONSTRAINT_RELATION_EQ,
+                                                y,
+                                                GTK_CONSTRAINT_STRENGTH_WEAK);
+      g_object_set_data (G_OBJECT (constraint), "internal", "yes");
+      gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                            constraint);
+      g_object_set_data (G_OBJECT (child), "y-constraint", constraint);
+    }
+}
+
+static void
+drag_begin (GtkGestureDrag *drag,
+            double          start_x,
+            double          start_y,
+            ConstraintView *self)
+{
+  GtkWidget *widget;
+  GtkWidget *target;
+
+  widget = gtk_widget_pick (GTK_WIDGET (self), start_x, start_y, GTK_PICK_DEFAULT);
+
+  if (widget)
+    {
+      target = gtk_widget_get_ancestor (widget, GUIDE_PLACEHOLDER_TYPE);
+      if (!target)
+        target = gtk_widget_get_ancestor (widget, GTK_TYPE_FRAME);
+      if (target &&
+          gtk_widget_get_parent (target) == (GtkWidget *)self)
+        {
+          self->drag_widget = target;
+        }
+    }
+}
+
+static void
+drag_update (GtkGestureDrag *drag,
+             double          offset_x,
+             double          offset_y,
+             ConstraintView *self)
+{
+  double x, y;
+
+  if (!self->drag_widget)
+    return;
+
+  gtk_gesture_drag_get_start_point (drag, &x, &y);
+  update_weak_position (self, self->drag_widget, x + offset_x, y + offset_y);
+}
+
+static void
+drag_end (GtkGestureDrag *drag,
+          double          offset_x,
+          double          offset_y,
+          ConstraintView *self)
+{
+  self->drag_widget = NULL;
+}
+
+static gboolean
+omit_internal (gpointer item, gpointer user_data)
+{
+  if (g_object_get_data (G_OBJECT (item), "internal"))
+    return FALSE;
+
+  return TRUE;
+}
+
+static void
+constraint_view_init (ConstraintView *self)
+{
+  GtkLayoutManager *manager;
+  GtkEventController *controller;
+  GListStore *list;
+  GListModel *all_children;
+  GListModel *all_constraints;
+  GListModel *guides;
+  GListModel *children;
+  GListModel *constraints;
+
+  manager = gtk_constraint_layout_new ();
+  gtk_widget_set_layout_manager (GTK_WIDGET (self), manager);
+
+  all_children = gtk_widget_observe_children (GTK_WIDGET (self));
+  all_constraints = gtk_constraint_layout_observe_constraints (GTK_CONSTRAINT_LAYOUT (manager));
+  guides = gtk_constraint_layout_observe_guides (GTK_CONSTRAINT_LAYOUT (manager));
+  constraints = (GListModel *)gtk_filter_list_model_new (all_constraints, omit_internal, NULL, NULL);
+  children = (GListModel *)gtk_filter_list_model_new (all_children, omit_internal, NULL, NULL);
+
+  list = g_list_store_new (G_TYPE_LIST_MODEL);
+  g_list_store_append (list, children);
+  g_list_store_append (list, guides);
+  g_list_store_append (list, constraints);
+  self->model = G_LIST_MODEL (gtk_flatten_list_model_new (G_TYPE_OBJECT, G_LIST_MODEL (list)));
+  g_object_unref (children);
+  g_object_unref (guides);
+  g_object_unref (constraints);
+  g_object_unref (all_children);
+  g_object_unref (all_constraints);
+  g_object_unref (list);
+
+
+  controller = (GtkEventController *)gtk_gesture_drag_new ();
+  g_signal_connect (controller, "drag-begin", G_CALLBACK (drag_begin), self);
+  g_signal_connect (controller, "drag-update", G_CALLBACK (drag_update), self);
+  g_signal_connect (controller, "drag-end", G_CALLBACK (drag_end), self);
+  gtk_widget_add_controller (GTK_WIDGET (self), controller);
+}
+
+ConstraintView *
+constraint_view_new (void)
+{
+  return g_object_new (CONSTRAINT_VIEW_TYPE, NULL);
+}
+
+void
+constraint_view_add_child (ConstraintView *view,
+                           const char     *name)
+{
+  GtkWidget *frame;
+  GtkWidget *label;
+
+  frame = gtk_frame_new (NULL);
+  gtk_style_context_add_class (gtk_widget_get_style_context (frame), "child");
+  gtk_widget_set_name (frame, name);
+  gtk_widget_set_size_request (frame, 100, 25);
+  label = gtk_label_new (name);
+  gtk_container_add (GTK_CONTAINER (frame), label);
+  g_object_bind_property (frame, "name",
+                          label, "label",
+                          G_BINDING_DEFAULT);
+
+  gtk_widget_set_parent (frame, GTK_WIDGET (view));
+
+  update_weak_position (view, frame, 100, 100);
+}
+
+void
+constraint_view_remove_child (ConstraintView *view,
+                              GtkWidget      *child)
+{
+  update_weak_position (view, child, -100, -100);
+  gtk_widget_unparent (child);
+}
+
+void
+constraint_view_add_guide (ConstraintView *view,
+                           GtkConstraintGuide *guide)
+{
+  GtkConstraintLayout *layout;
+  GtkWidget *placeholder;
+  const char *name;
+  GtkConstraint *constraint;
+  struct {
+    const char *name;
+    GtkConstraintAttribute attr;
+  } names[] = {
+    { "left-constraint", GTK_CONSTRAINT_ATTRIBUTE_LEFT },
+    { "top-constraint", GTK_CONSTRAINT_ATTRIBUTE_TOP },
+    { "width-constraint", GTK_CONSTRAINT_ATTRIBUTE_WIDTH },
+    { "height-constraint", GTK_CONSTRAINT_ATTRIBUTE_HEIGHT },
+  };
+  int i;
+
+  name = gtk_constraint_guide_get_name (guide);
+
+  placeholder = guide_placeholder_new (guide);
+  gtk_widget_set_tooltip_text (placeholder, name);
+  g_object_bind_property (guide, "name",
+                          placeholder, "tooltip-text",
+                          G_BINDING_DEFAULT);
+
+  g_object_set_data (G_OBJECT (placeholder), "internal", "yes");
+  gtk_widget_insert_after (placeholder, GTK_WIDGET (view), NULL);
+
+  g_object_set_data (G_OBJECT (guide), "placeholder", placeholder);
+
+  layout = GTK_CONSTRAINT_LAYOUT (gtk_widget_get_layout_manager (GTK_WIDGET (view)));
+  gtk_constraint_layout_add_guide (layout, g_object_ref (guide));
+
+  for (i = 0; i < G_N_ELEMENTS (names); i++)
+    {
+      constraint = gtk_constraint_new (placeholder,
+                                       names[i].attr,
+                                       GTK_CONSTRAINT_RELATION_EQ,
+                                       guide,
+                                       names[i].attr,
+                                       1.0, 0.0,
+                                       GTK_CONSTRAINT_STRENGTH_REQUIRED);
+      g_object_set_data (G_OBJECT (constraint), "internal", "yes");
+      gtk_constraint_layout_add_constraint (layout, constraint);
+      g_object_set_data (G_OBJECT (guide), names[i].name, constraint);
+    }
+
+  update_weak_position (view, placeholder, 150, 150);
+}
+
+void
+constraint_view_remove_guide (ConstraintView     *view,
+                              GtkConstraintGuide *guide)
+{
+  GtkConstraintLayout *layout;
+  GtkWidget *placeholder;
+  GtkConstraint *constraint;
+  const char *names[] = {
+    "left-constraint",
+    "top-constraint",
+    "width-constraint",
+    "height-constraint"
+  };
+  int i;
+
+  layout = GTK_CONSTRAINT_LAYOUT (gtk_widget_get_layout_manager (GTK_WIDGET (view)));
+
+  for (i = 0; i < G_N_ELEMENTS (names); i++)
+    {
+      constraint = (GtkConstraint*)g_object_get_data (G_OBJECT (guide), names[i]);
+      gtk_constraint_layout_remove_constraint (layout, constraint);
+    }
+
+  placeholder = (GtkWidget *)g_object_get_data (G_OBJECT (guide), "placeholder");
+  update_weak_position (view, placeholder, -100, -100);
+  gtk_widget_unparent (placeholder);
+
+  gtk_constraint_layout_remove_guide (layout, guide);
+}
+
+void
+constraint_view_add_constraint (ConstraintView *view,
+                                GtkConstraint  *constraint)
+{
+  GtkLayoutManager *manager;
+
+  manager = gtk_widget_get_layout_manager (GTK_WIDGET (view));
+  gtk_constraint_layout_add_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                        g_object_ref (constraint));
+}
+
+void
+constraint_view_remove_constraint (ConstraintView *view,
+                                   GtkConstraint  *constraint)
+{
+  GtkLayoutManager *manager;
+
+  manager = gtk_widget_get_layout_manager (GTK_WIDGET (view));
+  gtk_constraint_layout_remove_constraint (GTK_CONSTRAINT_LAYOUT (manager),
+                                           constraint);
+}
+
+GListModel *
+constraint_view_get_model (ConstraintView *view)
+{
+  return view->model;
+}
@@ -0,0 +1,44 @@
+/*
+ * Copyright © 2019 Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+#define CONSTRAINT_VIEW_TYPE (constraint_view_get_type ())
+
+G_DECLARE_FINAL_TYPE (ConstraintView, constraint_view, CONSTRAINT, VIEW, GtkWidget)
+
+ConstraintView * constraint_view_new (void);
+
+void             constraint_view_add_child (ConstraintView *view,
+                                            const char     *name);
+void             constraint_view_remove_child (ConstraintView *view,
+                                               GtkWidget      *child);
+void             constraint_view_add_guide (ConstraintView     *view,
+                                            GtkConstraintGuide *guide);
+void             constraint_view_remove_guide (ConstraintView     *view,
+                                               GtkConstraintGuide *guide);
+void             constraint_view_guide_changed (ConstraintView     *view,
+                                                GtkConstraintGuide *guide);
+void             constraint_view_add_constraint (ConstraintView *view,
+                                                 GtkConstraint  *constraint);
+void             constraint_view_remove_constraint (ConstraintView *view,
+                                                    GtkConstraint  *constraint);
+GListModel *     constraint_view_get_model (ConstraintView *view);
@@ -0,0 +1,411 @@
+/*
+ * Copyright © 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#include "config.h"
+
+#include "guide-editor.h"
+
+struct _GuideEditor
+{
+  GtkWidget parent_instance;
+
+  GtkWidget *grid;
+  GtkWidget *name;
+  GtkWidget *min_width;
+  GtkWidget *min_height;
+  GtkWidget *nat_width;
+  GtkWidget *nat_height;
+  GtkWidget *max_width;
+  GtkWidget *max_height;
+  GtkWidget *strength;
+  GtkWidget *button;
+
+  GtkConstraintGuide *guide;
+
+  gboolean constructed;
+};
+
+enum {
+  PROP_GUIDE = 1,
+  LAST_PROP
+};
+
+static GParamSpec *pspecs[LAST_PROP];
+
+enum {
+  DONE,
+  LAST_SIGNAL
+};
+
+static guint signals[LAST_SIGNAL];
+
+G_DEFINE_TYPE(GuideEditor, guide_editor, GTK_TYPE_WIDGET);
+
+static void
+guide_strength_combo (GtkWidget *combo)
+{
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "weak", "Weak");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "medium", "Medium");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "strong", "Strong");
+  gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo), "required", "Required");
+}
+
+static GtkConstraintStrength
+get_strength (const char *id)
+{
+  GtkConstraintStrength strength;
+  GEnumClass *class = g_type_class_ref (GTK_TYPE_CONSTRAINT_STRENGTH);
+  GEnumValue *value = g_enum_get_value_by_nick (class, id);
+  strength = value->value;
+  g_type_class_unref (class);
+
+  return strength;
+}
+
+const char *
+get_strength_nick (GtkConstraintStrength strength)
+{
+  GEnumClass *class = g_type_class_ref (GTK_TYPE_CONSTRAINT_STRENGTH);
+  GEnumValue *value = g_enum_get_value (class, strength);
+  const char *nick = value->value_nick;
+  g_type_class_unref (class);
+
+  return nick;
+}
+
+void
+guide_editor_serialize_guide (GString *str,
+                              int      indent,
+                              GtkConstraintGuide *guide)
+{
+  int min_width, min_height;
+  int nat_width, nat_height;
+  int max_width, max_height;
+  const char *name;
+  const char *strength;
+
+  gtk_constraint_guide_get_min_size (guide, &min_width, &min_height);
+  gtk_constraint_guide_get_nat_size (guide, &nat_width, &nat_height);
+  gtk_constraint_guide_get_max_size (guide, &max_width, &max_height);
+  name = gtk_constraint_guide_get_name (guide);
+  strength = get_strength_nick (gtk_constraint_guide_get_strength (guide));
+
+  g_string_append_printf (str, "%*s<guide min-width=\"%d\" min-height=\"%d\"\n", indent, "", min_width, min_height);
+  g_string_append_printf (str, "%*s       nat-width=\"%d\" nat-height=\"%d\"\n", indent, "", nat_width, nat_height);
+  g_string_append_printf (str, "%*s       max-width=\"%d\" max-height=\"%d\"\n", indent, "", max_width, max_height);
+  g_string_append_printf (str, "%*s       name=\"%s\" strength=\"%s\" />\n", indent, "", name, strength);
+}
+
+static void
+create_guide (GtkButton   *button,
+              GuideEditor *editor)
+{
+  const char *id;
+  int strength;
+  const char *name;
+  int w, h;
+  GtkConstraintGuide *guide;
+
+  if (editor->guide)
+    guide = g_object_ref (editor->guide);
+  else
+    guide = gtk_constraint_guide_new ();
+
+  name = gtk_editable_get_text (GTK_EDITABLE (editor->name));
+  gtk_constraint_guide_set_name (guide, name);
+
+  w = gtk_spin_button_get_value_as_int (GTK_SPIN_BUTTON (editor->min_width));
+  h = gtk_spin_button_get_value_as_int (GTK_SPIN_BUTTON (editor->min_height));
+  gtk_constraint_guide_set_min_size (guide, w, h);
+
+  w = gtk_spin_button_get_value_as_int (GTK_SPIN_BUTTON (editor->nat_width));
+  h = gtk_spin_button_get_value_as_int (GTK_SPIN_BUTTON (editor->nat_height));
+  gtk_constraint_guide_set_nat_size (guide, w, h);
+
+  w = gtk_spin_button_get_value_as_int (GTK_SPIN_BUTTON (editor->max_width));
+  h = gtk_spin_button_get_value_as_int (GTK_SPIN_BUTTON (editor->max_height));
+  gtk_constraint_guide_set_max_size (guide, w, h);
+
+  id = gtk_combo_box_get_active_id (GTK_COMBO_BOX (editor->strength));
+  strength = get_strength (id);
+  gtk_constraint_guide_set_strength (guide, strength);
+
+  g_signal_emit (editor, signals[DONE], 0, guide);
+  g_object_unref (guide);
+}
+
+static void
+guide_editor_init (GuideEditor *editor)
+{
+  gtk_widget_init_template (GTK_WIDGET (editor));
+}
+
+static int guide_counter;
+
+static int
+min_input (GtkSpinButton *spin_button,
+           double        *new_val)
+{
+  if (strcmp (gtk_editable_get_text (GTK_EDITABLE (spin_button)), "") == 0)
+    {
+      *new_val = 0.0;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static int
+max_input (GtkSpinButton *spin_button,
+           double        *new_val)
+{
+  if (strcmp (gtk_editable_get_text (GTK_EDITABLE (spin_button)), "") == 0)
+    {
+      *new_val = G_MAXINT;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static gboolean
+min_output (GtkSpinButton *spin_button)
+{
+  GtkAdjustment *adjustment;
+  double value;
+  GtkWidget *box, *text;
+
+  adjustment = gtk_spin_button_get_adjustment (spin_button);
+  value = gtk_adjustment_get_value (adjustment);
+
+  box = gtk_widget_get_first_child (GTK_WIDGET (spin_button));
+  text = gtk_widget_get_first_child (box);
+
+  if (value == 0.0)
+    {
+      gtk_editable_set_text (GTK_EDITABLE (spin_button), "");
+      gtk_text_set_placeholder_text (GTK_TEXT (text), "unset");
+      return TRUE;
+    }
+  else
+    {
+      gtk_text_set_placeholder_text (GTK_TEXT (text), "");
+      return FALSE;
+    }
+}
+
+static gboolean
+max_output (GtkSpinButton *spin_button)
+{
+  GtkAdjustment *adjustment;
+  double value;
+  GtkWidget *box, *text;
+
+  adjustment = gtk_spin_button_get_adjustment (spin_button);
+  value = gtk_adjustment_get_value (adjustment);
+
+  box = gtk_widget_get_first_child (GTK_WIDGET (spin_button));
+  text = gtk_widget_get_first_child (box);
+
+  if (value == (double)G_MAXINT)
+    {
+      gtk_editable_set_text (GTK_EDITABLE (spin_button), "");
+      gtk_text_set_placeholder_text (GTK_TEXT (text), "unset");
+      return TRUE;
+    }
+  else
+    {
+      gtk_text_set_placeholder_text (GTK_TEXT (text), "");
+      return FALSE;
+    }
+}
+
+static void
+guide_editor_constructed (GObject *object)
+{
+  GuideEditor *editor = GUIDE_EDITOR (object);
+
+  guide_strength_combo (editor->strength);
+
+  g_signal_connect (editor->min_width, "input", G_CALLBACK (min_input), NULL);
+  g_signal_connect (editor->min_width, "output", G_CALLBACK (min_output), NULL);
+
+  g_signal_connect (editor->min_height, "input", G_CALLBACK (min_input), NULL);
+  g_signal_connect (editor->min_height, "output", G_CALLBACK (min_output), NULL);
+
+  g_signal_connect (editor->max_width, "input", G_CALLBACK (max_input), NULL);
+  g_signal_connect (editor->max_width, "output", G_CALLBACK (max_output), NULL);
+
+  g_signal_connect (editor->max_height, "input", G_CALLBACK (max_input), NULL);
+  g_signal_connect (editor->max_height, "output", G_CALLBACK (max_output), NULL);
+
+  if (editor->guide)
+    {
+      GtkConstraintStrength strength;
+      const char *nick;
+      int w, h;
+
+      nick = gtk_constraint_guide_get_name (editor->guide);
+      if (nick)
+        gtk_editable_set_text (GTK_EDITABLE (editor->name), nick);
+
+      gtk_constraint_guide_get_min_size (editor->guide, &w, &h);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->min_width), w);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->min_height), h);
+
+      gtk_constraint_guide_get_nat_size (editor->guide, &w, &h);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->nat_width), w);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->nat_height), h);
+
+      gtk_constraint_guide_get_max_size (editor->guide, &w, &h);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->max_width), w);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->max_height), h);
+
+      strength = gtk_constraint_guide_get_strength (editor->guide);
+      nick = get_strength_nick (strength);
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->strength), nick);
+
+      gtk_button_set_label (GTK_BUTTON (editor->button), "Apply");
+    }
+  else
+    {
+      char *name;
+
+      guide_counter++;
+      name = g_strdup_printf ("Guide %d", guide_counter);
+      gtk_editable_set_text (GTK_EDITABLE (editor->name), name);
+      g_free (name);
+
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->min_width), 0.0);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->min_height), 0.0);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->nat_width), 0.0);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->nat_height), 0.0);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->max_width), G_MAXINT);
+      gtk_spin_button_set_value (GTK_SPIN_BUTTON (editor->max_height), G_MAXINT);
+
+      gtk_combo_box_set_active_id (GTK_COMBO_BOX (editor->strength), "medium");
+
+      gtk_button_set_label (GTK_BUTTON (editor->button), "Create");
+    }
+
+  editor->constructed = TRUE;
+}
+
+static void
+guide_editor_set_property (GObject      *object,
+                           guint         property_id,
+                           const GValue *value,
+                           GParamSpec   *pspec)
+{
+  GuideEditor *self = GUIDE_EDITOR (object);
+
+  switch (property_id)
+    {
+    case PROP_GUIDE:
+      self->guide = g_value_dup_object (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+    }
+}
+
+static void
+guide_editor_get_property (GObject    *object,
+                           guint       property_id,
+                           GValue     *value,
+                           GParamSpec *pspec)
+{
+  GuideEditor *self = GUIDE_EDITOR (object);
+
+  switch (property_id)
+    {
+    case PROP_GUIDE:
+      g_value_set_object (value, self->guide);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+    }
+}
+
+static void
+guide_editor_dispose (GObject *object)
+{
+  GuideEditor *self = (GuideEditor *)object;
+
+  g_clear_pointer (&self->grid, gtk_widget_unparent);
+  g_clear_object (&self->guide);
+
+  G_OBJECT_CLASS (guide_editor_parent_class)->dispose (object);
+}
+
+static void
+guide_editor_class_init (GuideEditorClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
+
+  object_class->constructed = guide_editor_constructed;
+  object_class->dispose = guide_editor_dispose;
+  object_class->set_property = guide_editor_set_property;
+  object_class->get_property = guide_editor_get_property;
+
+  pspecs[PROP_GUIDE] =
+    g_param_spec_object ("guide", "guide", "guide",
+                         GTK_TYPE_CONSTRAINT_GUIDE,
+                         G_PARAM_READWRITE|G_PARAM_CONSTRUCT_ONLY);
+
+  g_object_class_install_properties (object_class, LAST_PROP, pspecs);
+
+  signals[DONE] =
+    g_signal_new ("done",
+                  G_TYPE_FROM_CLASS (object_class),
+                  G_SIGNAL_RUN_LAST,
+                  0,
+                  NULL, NULL,
+                  NULL,
+                  G_TYPE_NONE, 1, GTK_TYPE_CONSTRAINT_GUIDE);
+
+  gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_BIN_LAYOUT);
+
+  gtk_widget_class_set_template_from_resource (widget_class,
+                                               "/org/gtk/gtk4/constraint-editor/guide-editor.ui");
+
+  gtk_widget_class_bind_template_child (widget_class, GuideEditor, grid);
+  gtk_widget_class_bind_template_child (widget_class, GuideEditor, name);
+  gtk_widget_class_bind_template_child (widget_class, GuideEditor, min_width);
+  gtk_widget_class_bind_template_child (widget_class, GuideEditor, min_height);
+  gtk_widget_class_bind_template_child (widget_class, GuideEditor, nat_width);
+  gtk_widget_class_bind_template_child (widget_class, GuideEditor, nat_height);
+  gtk_widget_class_bind_template_child (widget_class, GuideEditor, max_width);
+  gtk_widget_class_bind_template_child (widget_class, GuideEditor, max_height);
+  gtk_widget_class_bind_template_child (widget_class, GuideEditor, strength);
+  gtk_widget_class_bind_template_child (widget_class, GuideEditor, button);
+
+  gtk_widget_class_bind_template_callback (widget_class, create_guide);
+}
+
+GuideEditor *
+guide_editor_new (GtkConstraintGuide *guide)
+{
+  return g_object_new (GUIDE_EDITOR_TYPE,
+                       "guide", guide,
+                       NULL);
+}
@@ -0,0 +1,32 @@
+/*
+ * Copyright © 2019 Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+#define GUIDE_EDITOR_TYPE (guide_editor_get_type ())
+
+G_DECLARE_FINAL_TYPE (GuideEditor, guide_editor, GUIDE, EDITOR, GtkWidget)
+
+GuideEditor * guide_editor_new (GtkConstraintGuide  *guide);
+
+void guide_editor_serialize_guide (GString            *str,
+                                   int                 indent,
+                                   GtkConstraintGuide *guide);
@@ -0,0 +1,188 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <object class="GtkAdjustment" id="min_width_adj">
+    <property name="lower">0</property>
+    <property name="upper">2147483647</property>
+    <property name="step-increment">1</property>
+    <property name="page-increment">10</property>
+    <property name="page-size">0</property>
+  </object>
+  <object class="GtkAdjustment" id="min_height_adj">
+    <property name="lower">0</property>
+    <property name="upper">2147483647</property>
+    <property name="step-increment">1</property>
+    <property name="page-increment">10</property>
+    <property name="page-size">0</property>
+  </object>
+  <object class="GtkAdjustment" id="nat_width_adj">
+    <property name="lower">0</property>
+    <property name="upper">2147483647</property>
+    <property name="step-increment">1</property>
+    <property name="page-increment">10</property>
+    <property name="page-size">0</property>
+  </object>
+  <object class="GtkAdjustment" id="nat_height_adj">
+    <property name="lower">0</property>
+    <property name="upper">2147483647</property>
+    <property name="step-increment">1</property>
+    <property name="page-increment">10</property>
+    <property name="page-size">0</property>
+  </object>
+  <object class="GtkAdjustment" id="max_width_adj">
+    <property name="lower">0</property>
+    <property name="upper">2147483647</property>
+    <property name="step-increment">1</property>
+    <property name="page-increment">10</property>
+    <property name="page-size">0</property>
+  </object>
+  <object class="GtkAdjustment" id="max_height_adj">
+    <property name="lower">0</property>
+    <property name="upper">2147483647</property>
+    <property name="step-increment">1</property>
+    <property name="page-increment">10</property>
+    <property name="page-size">0</property>
+  </object>
+  <template class="GuideEditor" parent="GtkWidget">
+    <child>
+      <object class="GtkGrid" id="grid">
+        <property name="margin">20</property>
+        <property name="row-spacing">10</property>
+        <property name="column-spacing">10</property>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Name</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">0</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkEntry" id="name">
+            <property name="max-width-chars">20</property>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">0</property>
+              <property name="column-span">2</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Min Size</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkSpinButton" id="min_width">
+            <property name="adjustment">min_width_adj</property>
+            <property name="max-width-chars">5</property>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkSpinButton" id="min_height">
+            <property name="adjustment">min_height_adj</property>
+            <property name="max-width-chars">5</property>
+            <layout>
+              <property name="left-attach">2</property>
+              <property name="top-attach">1</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Nat Size</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">2</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkSpinButton" id="nat_width">
+            <property name="adjustment">nat_width_adj</property>
+            <property name="max-width-chars">5</property>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">2</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkSpinButton" id="nat_height">
+            <property name="adjustment">nat_height_adj</property>
+            <property name="max-width-chars">5</property>
+            <layout>
+              <property name="left-attach">2</property>
+              <property name="top-attach">2</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Max Size</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">3</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkSpinButton" id="max_width">
+            <property name="adjustment">max_width_adj</property>
+            <property name="max-width-chars">5</property>
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">3</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkSpinButton" id="max_height">
+            <property name="adjustment">max_height_adj</property>
+            <property name="max-width-chars">5</property>
+            <layout>
+              <property name="left-attach">2</property>
+              <property name="top-attach">3</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Strength</property>
+            <layout>
+              <property name="left-attach">0</property>
+              <property name="top-attach">4</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkComboBoxText" id="strength">
+            <layout>
+              <property name="left-attach">1</property>
+              <property name="top-attach">4</property>
+              <property name="column-span">2</property>
+            </layout>
+          </object>
+        </child>
+        <child>
+          <object class="GtkButton" id="button">
+            <property name="label">Create</property>
+            <signal name="clicked" handler="create_guide"/>
+            <layout>
+              <property name="left-attach">2</property>
+              <property name="top-attach">5</property>
+            </layout>
+          </object>
+        </child>
+      </object>
+    </child>
+  </template>
+</interface>
@@ -0,0 +1,179 @@
+/*
+ * Copyright © 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#include "config.h"
+
+#include "guide-placeholder.h"
+
+struct _GuidePlaceholder {
+  GtkWidget parent_instance;
+
+  GtkWidget *label;
+
+  GtkConstraintGuide *guide;
+};
+
+enum {
+  PROP_GUIDE = 1,
+  LAST_PROP
+};
+
+static GParamSpec *props[LAST_PROP];
+
+
+G_DEFINE_TYPE (GuidePlaceholder, guide_placeholder, GTK_TYPE_WIDGET);
+
+static void
+guide_placeholder_measure (GtkWidget      *widget,
+                           GtkOrientation  orientation,
+                           int             for_size,
+                           int            *minimum,
+                           int            *natural,
+                           int            *minimum_baseline,
+                           int            *natural_baseline)
+{
+  GuidePlaceholder *self = GUIDE_PLACEHOLDER (widget);
+  int min_width, min_height;
+  int nat_width, nat_height;
+
+  gtk_constraint_guide_get_min_size (self->guide, &min_width, &min_height);
+  gtk_constraint_guide_get_nat_size (self->guide, &nat_width, &nat_height);
+
+  gtk_widget_measure (self->label, orientation, for_size, minimum, natural, NULL, NULL);
+
+  if (orientation == GTK_ORIENTATION_HORIZONTAL)
+    {
+      *minimum = min_width;
+      *natural = nat_width;
+    }
+  else
+    {
+      *minimum = min_height;
+      *natural = nat_height;
+    }
+}
+
+static void
+guide_placeholder_size_allocate (GtkWidget *widget,
+                                 int        width,
+                                 int        height,
+                                 int        baseline)
+{
+  GuidePlaceholder *self = GUIDE_PLACEHOLDER (widget);
+
+  gtk_widget_allocate (self->label, width, height, baseline, NULL);
+}
+
+static void
+guide_changed (GObject *obj, GParamSpec *pspec, GuidePlaceholder *self)
+{
+  gtk_label_set_label (GTK_LABEL (self->label), gtk_constraint_guide_get_name (self->guide));
+  gtk_widget_queue_resize (GTK_WIDGET (self));
+}
+
+static void
+guide_placeholder_dispose (GObject *object)
+{
+  GuidePlaceholder *self = GUIDE_PLACEHOLDER (object);
+
+  g_signal_handlers_disconnect_by_func (self->guide, guide_changed, self);
+  g_object_unref (self->guide);
+
+  gtk_widget_unparent (self->label);
+
+  G_OBJECT_CLASS (guide_placeholder_parent_class)->dispose (object);
+}
+
+static void
+guide_placeholder_set_property (GObject      *object,
+                                guint         prop_id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  GuidePlaceholder *self = GUIDE_PLACEHOLDER (object);
+
+  switch (prop_id)
+    {
+    case PROP_GUIDE:
+      self->guide = g_value_dup_object (value);
+      g_signal_connect (self->guide, "notify", G_CALLBACK (guide_changed), self);
+      guide_changed ((GObject *)self->guide, NULL, self);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+guide_placeholder_get_property (GObject     *object,
+                                guint        prop_id,
+                                GValue      *value,
+                                GParamSpec  *pspec)
+{
+  GuidePlaceholder *self = GUIDE_PLACEHOLDER (object);
+
+  switch (prop_id)
+    {
+    case PROP_GUIDE:
+      g_value_set_object (value, self->guide);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+guide_placeholder_class_init (GuidePlaceholderClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  object_class->dispose = guide_placeholder_dispose;
+  object_class->set_property = guide_placeholder_set_property;
+  object_class->get_property = guide_placeholder_get_property;
+
+  widget_class->measure = guide_placeholder_measure;
+  widget_class->size_allocate = guide_placeholder_size_allocate;
+
+  props[PROP_GUIDE] =
+    g_param_spec_object ("guide", "guide", "guide",
+                         GTK_TYPE_CONSTRAINT_GUIDE,
+                         G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY);
+
+  g_object_class_install_properties (object_class, LAST_PROP, props);
+
+  gtk_widget_class_set_css_name (widget_class, "guide");
+}
+
+static void
+guide_placeholder_init (GuidePlaceholder *self)
+{
+  self->label = gtk_label_new ("");
+  gtk_widget_set_parent (self->label, GTK_WIDGET (self));
+}
+
+GtkWidget *
+guide_placeholder_new (GtkConstraintGuide *guide)
+{
+  return g_object_new (guide_placeholder_get_type (),
+                       "guide", guide,
+                       NULL);
+}
@@ -0,0 +1,28 @@
+/*
+ * Copyright © 2019 Red Hat, Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen
+ */
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+#define GUIDE_PLACEHOLDER_TYPE (guide_placeholder_get_type ())
+
+G_DECLARE_FINAL_TYPE (GuidePlaceholder, guide_placeholder, GUIDE, PLACEHOLDER, GtkWidget)
+
+GtkWidget * guide_placeholder_new (GtkConstraintGuide  *guide);
@@ -0,0 +1,28 @@
+/*
+ * Copyright © 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Matthias Clasen <mclasen@redhat.com>
+ */
+
+#include "config.h"
+
+#include <constraint-editor-application.h>
+
+int
+main (int argc, char *argv[])
+{
+  return g_application_run (G_APPLICATION (constraint_editor_application_new ()), argc, argv);
+}
@@ -0,0 +1,21 @@
+constraint_editor_sources = [
+  'main.c',
+  'constraint-editor-application.c',
+  'constraint-editor-window.c',
+  'constraint-view.c',
+  'constraint-editor.c',
+  'guide-editor.c',
+  'child-editor.c',
+  'guide-placeholder.c',
+]
+
+constraint_editor_resources = gnome.compile_resources('constraint_editor_resources',
+                                                      'constraint-editor.gresource.xml',
+                                                      source_dir: '.')
+
+executable('gtk4-constraint-editor',
+           constraint_editor_sources, constraint_editor_resources,
+           dependencies: libgtk_dep,
+           include_directories: confinc,
+           gui_app: true,
+           install: false)
@@ -0,0 +1,289 @@
+/* Constraints/Simple
+ *
+ * GtkConstraintLayout provides a layout manager that uses relations
+ * between widgets (also known as "constraints") to compute the position
+ * and size of each child.
+ */
+
+#include <glib/gi18n.h>
+#include <gtk/gtk.h>
+
+G_DECLARE_FINAL_TYPE (SimpleGrid, simple_grid, SIMPLE, GRID, GtkWidget)
+
+struct _SimpleGrid
+{
+  GtkWidget parent_instance;
+
+  GtkWidget *button1, *button2;
+  GtkWidget *button3;
+};
+
+G_DEFINE_TYPE (SimpleGrid, simple_grid, GTK_TYPE_WIDGET)
+
+static void
+simple_grid_destroy (GtkWidget *widget)
+{
+  SimpleGrid *self = SIMPLE_GRID (widget);
+
+  g_clear_pointer (&self->button1, gtk_widget_destroy);
+  g_clear_pointer (&self->button2, gtk_widget_destroy);
+  g_clear_pointer (&self->button3, gtk_widget_destroy);
+
+  GTK_WIDGET_CLASS (simple_grid_parent_class)->destroy (widget);
+}
+
+static void
+simple_grid_class_init (SimpleGridClass *klass)
+{
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  widget_class->destroy = simple_grid_destroy;
+
+  gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_CONSTRAINT_LAYOUT);
+}
+
+/* Layout:
+ *
+ *   +-------------------------------------+
+ *   | +-----------++-------++-----------+ |
+ *   | |  Child 1  || Space ||  Child 2  | |
+ *   | +-----------++-------++-----------+ |
+ *   | +---------------------------------+ |
+ *   | |             Child 3             | |
+ *   | +---------------------------------+ |
+ *   +-------------------------------------+
+ *
+ * Constraints:
+ *
+ *   super.start = child1.start - 8
+ *   child1.width = child2.width
+ *   child1.end = space.start
+ *   space.end = child2.start
+ *   child2.end = super.end - 8
+ *   super.start = child3.start - 8
+ *   child3.end = super.end - 8
+ *   super.top = child1.top - 8
+ *   super.top = child2.top - 8
+ *   child1.bottom = child3.top - 12
+ *   child2.bottom = child3.top - 12
+ *   child3.height = child1.height
+ *   child3.height = child2.height
+ *   child3.bottom = super.bottom - 8
+ *
+ * To add some flexibility, we make the space
+ * stretchable:
+ *
+ *   space.width >= 10
+ *   space.width = 100
+ *   space.width <= 200
+ */
+static void
+build_constraints (SimpleGrid          *self,
+                   GtkConstraintLayout *manager)
+{
+  GtkConstraintGuide *guide;
+
+  guide = gtk_constraint_guide_new ();
+  gtk_constraint_guide_set_name (guide, "space");
+  gtk_constraint_guide_set_min_size (guide, 10, 10);
+  gtk_constraint_guide_set_nat_size (guide, 100, 10);
+  gtk_constraint_guide_set_max_size (guide, 200, 20);
+  gtk_constraint_guide_set_strength (guide, GTK_CONSTRAINT_STRENGTH_STRONG);
+  gtk_constraint_layout_add_guide (manager, guide);
+
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new_constant (GTK_CONSTRAINT_TARGET (self->button1),
+                        GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
+                        GTK_CONSTRAINT_RELATION_LE,
+                        200.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        self->button1,
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (self->button1,
+                        GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        self->button2,
+                        GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
+                        1.0,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (self->button1,
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        guide,
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        1.0,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (guide,
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        self->button2,
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        1.0,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (self->button2,
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        self->button3,
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (self->button3,
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        self->button1,
+                        GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        self->button2,
+                        GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (self->button1,
+                        GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        self->button3,
+                        GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                        1.0,
+                        -12.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (self->button2,
+                        GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        self->button3,
+                        GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                        1.0,
+                        -12.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (self->button3,
+                        GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        self->button1,
+                        GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
+                        1.0,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (self->button3,
+                        GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        self->button2,
+                        GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
+                        1.0,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (self->button3,
+                        GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+}
+
+static void
+simple_grid_init (SimpleGrid *self)
+{
+  GtkWidget *widget = GTK_WIDGET (self);
+
+  self->button1 = gtk_button_new_with_label ("Child 1");
+  gtk_widget_set_parent (self->button1, widget);
+  gtk_widget_set_name (self->button1, "button1");
+
+  self->button2 = gtk_button_new_with_label ("Child 2");
+  gtk_widget_set_parent (self->button2, widget);
+  gtk_widget_set_name (self->button2, "button2");
+
+  self->button3 = gtk_button_new_with_label ("Child 3");
+  gtk_widget_set_parent (self->button3, widget);
+  gtk_widget_set_name (self->button3, "button3");
+
+  GtkLayoutManager *manager = gtk_widget_get_layout_manager (GTK_WIDGET (self));
+  build_constraints (self, GTK_CONSTRAINT_LAYOUT (manager));
+}
+
+GtkWidget *
+do_constraints (GtkWidget *do_widget)
+{
+ static GtkWidget *window;
+
+ if (!window)
+   {
+     GtkWidget *header, *box, *grid, *button;
+
+     window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+     gtk_window_set_display (GTK_WINDOW (window), gtk_widget_get_display (do_widget));
+
+     header = gtk_header_bar_new ();
+     gtk_header_bar_set_title (GTK_HEADER_BAR (header), "Constraints");
+     gtk_header_bar_set_show_title_buttons (GTK_HEADER_BAR (header), FALSE);
+     gtk_window_set_titlebar (GTK_WINDOW (window), header);
+     g_signal_connect (window, "destroy",
+                       G_CALLBACK (gtk_widget_destroyed), &window);
+
+     box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 12);
+     gtk_container_add (GTK_CONTAINER (window), box);
+
+     grid = g_object_new (simple_grid_get_type (), NULL);
+     gtk_widget_set_hexpand (grid, TRUE);
+     gtk_widget_set_vexpand (grid, TRUE);
+     gtk_container_add (GTK_CONTAINER (box), grid);
+
+     button = gtk_button_new_with_label ("Close");
+     gtk_container_add (GTK_CONTAINER (box), button);
+     gtk_widget_set_hexpand (grid, TRUE);
+     g_signal_connect_swapped (button, "clicked",
+                               G_CALLBACK (gtk_widget_destroy), window);
+   }
+
+ if (!gtk_widget_get_visible (window))
+   gtk_widget_show (window);
+ else
+   gtk_widget_destroy (window);
+
+ return window;
+}
@@ -0,0 +1,245 @@
+/* Constraints/Interactive
+ *
+ * Demonstrate how constraints can be updates during
+ * user interaction.
+ */
+
+#include <glib/gi18n.h>
+#include <gtk/gtk.h>
+
+G_DECLARE_FINAL_TYPE (InteractiveGrid, interactive_grid, INTERACTIVE, GRID, GtkWidget)
+
+struct _InteractiveGrid
+{
+  GtkWidget parent_instance;
+
+  GtkWidget *button1, *button2;
+  GtkWidget *button3;
+  GtkConstraintGuide *guide;
+  GtkConstraint *constraint;
+};
+
+G_DEFINE_TYPE (InteractiveGrid, interactive_grid, GTK_TYPE_WIDGET)
+
+static void
+interactive_grid_destroy (GtkWidget *widget)
+{
+  InteractiveGrid *self = INTERACTIVE_GRID (widget);
+
+  g_clear_pointer (&self->button1, gtk_widget_destroy);
+  g_clear_pointer (&self->button2, gtk_widget_destroy);
+  g_clear_pointer (&self->button3, gtk_widget_destroy);
+
+  GTK_WIDGET_CLASS (interactive_grid_parent_class)->destroy (widget);
+}
+
+static void
+interactive_grid_class_init (InteractiveGridClass *klass)
+{
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  widget_class->destroy = interactive_grid_destroy;
+
+  gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_CONSTRAINT_LAYOUT);
+}
+
+static void
+build_constraints (InteractiveGrid          *self,
+                   GtkConstraintLayout *manager)
+{
+  self->guide = g_object_new (GTK_TYPE_CONSTRAINT_GUIDE, NULL);
+  gtk_constraint_layout_add_guide (manager, self->guide);
+
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new_constant (GTK_CONSTRAINT_TARGET (self->guide),
+                        GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        GTK_CONSTRAINT_TARGET (self->button1),
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (GTK_CONSTRAINT_TARGET (self->button1),
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        GTK_CONSTRAINT_TARGET (self->guide),
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        1.0,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (GTK_CONSTRAINT_TARGET (self->button2),
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        GTK_CONSTRAINT_TARGET (self->guide),
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        1.0,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (GTK_CONSTRAINT_TARGET (self->button2),
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        GTK_CONSTRAINT_TARGET (self->button3),
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (GTK_CONSTRAINT_TARGET (self->button3),
+                        GTK_CONSTRAINT_ATTRIBUTE_END,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        GTK_CONSTRAINT_TARGET (self->guide),
+                        GTK_CONSTRAINT_ATTRIBUTE_START,
+                        1.0,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        GTK_CONSTRAINT_TARGET (self->button1),
+                        GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (GTK_CONSTRAINT_TARGET (self->button2),
+                        GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        GTK_CONSTRAINT_TARGET (self->button1),
+                        GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
+                        1.0,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (GTK_CONSTRAINT_TARGET (self->button3),
+                        GTK_CONSTRAINT_ATTRIBUTE_TOP,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        GTK_CONSTRAINT_TARGET (self->button2),
+                        GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
+                        1.0,
+                        0.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+  gtk_constraint_layout_add_constraint (manager,
+    gtk_constraint_new (GTK_CONSTRAINT_TARGET (self->button3),
+                        GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
+                        GTK_CONSTRAINT_RELATION_EQ,
+                        NULL,
+                        GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
+                        1.0,
+                        -8.0,
+                        GTK_CONSTRAINT_STRENGTH_REQUIRED));
+}
+
+static void
+drag_cb (GtkGestureDrag  *drag,
+         double           offset_x,
+         double           offset_y,
+         InteractiveGrid *self)
+{
+  GtkConstraintLayout *layout = GTK_CONSTRAINT_LAYOUT (gtk_widget_get_layout_manager (GTK_WIDGET (self)));
+  double x, y;
+
+  if (self->constraint)
+    {
+      gtk_constraint_layout_remove_constraint (layout, self->constraint);
+      g_clear_object (&self->constraint);
+    }
+
+  gtk_gesture_drag_get_start_point (drag, &x, &y);
+  self->constraint = gtk_constraint_new_constant (GTK_CONSTRAINT_TARGET (self->guide),
+                                                  GTK_CONSTRAINT_ATTRIBUTE_LEFT,
+                                                  GTK_CONSTRAINT_RELATION_EQ,
+                                                  x + offset_x,
+                                                  GTK_CONSTRAINT_STRENGTH_REQUIRED);
+  gtk_constraint_layout_add_constraint (layout, g_object_ref (self->constraint));
+  gtk_widget_queue_allocate (GTK_WIDGET (self));
+}
+
+static void
+interactive_grid_init (InteractiveGrid *self)
+{
+  GtkWidget *widget = GTK_WIDGET (self);
+  GtkGesture *drag;
+
+  self->button1 = gtk_button_new_with_label ("Child 1");
+  gtk_widget_set_parent (self->button1, widget);
+  gtk_widget_set_name (self->button1, "button1");
+
+  self->button2 = gtk_button_new_with_label ("Child 2");
+  gtk_widget_set_parent (self->button2, widget);
+  gtk_widget_set_name (self->button2, "button2");
+
+  self->button3 = gtk_button_new_with_label ("Child 3");
+  gtk_widget_set_parent (self->button3, widget);
+  gtk_widget_set_name (self->button3, "button3");
+
+  GtkLayoutManager *manager = gtk_widget_get_layout_manager (GTK_WIDGET (self));
+  build_constraints (self, GTK_CONSTRAINT_LAYOUT (manager));
+
+  drag = gtk_gesture_drag_new ();
+  g_signal_connect (drag, "drag-update", G_CALLBACK (drag_cb), self);
+  gtk_widget_add_controller (GTK_WIDGET (self), GTK_EVENT_CONTROLLER (drag));
+}
+
+GtkWidget *
+do_constraints2 (GtkWidget *do_widget)
+{
+ static GtkWidget *window;
+
+ if (!window)
+   {
+     GtkWidget *header, *box, *grid, *button;
+
+     window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+     gtk_window_set_display (GTK_WINDOW (window), gtk_widget_get_display (do_widget));
+
+     header = gtk_header_bar_new ();
+     gtk_header_bar_set_title (GTK_HEADER_BAR (header), "Constraints");
+     gtk_header_bar_set_show_title_buttons (GTK_HEADER_BAR (header), FALSE);
+     gtk_window_set_titlebar (GTK_WINDOW (window), header);
+     g_signal_connect (window, "destroy",
+                       G_CALLBACK (gtk_widget_destroyed), &window);
+
+     box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 12);
+     gtk_container_add (GTK_CONTAINER (window), box);
+
+     grid = g_object_new (interactive_grid_get_type (), NULL);
+     gtk_widget_set_hexpand (grid, TRUE);
+     gtk_widget_set_vexpand (grid, TRUE);
+     gtk_container_add (GTK_CONTAINER (box), grid);
+
+     button = gtk_button_new_with_label ("Close");
+     gtk_container_add (GTK_CONTAINER (box), button);
+     gtk_widget_set_hexpand (grid, TRUE);
+     g_signal_connect_swapped (button, "clicked",
+                               G_CALLBACK (gtk_widget_destroy), window);
+   }
+
+ if (!gtk_widget_get_visible (window))
+   gtk_widget_show (window);
+ else
+   gtk_widget_destroy (window);
+
+ return window;
+}
@@ -0,0 +1,165 @@
+/* Constraints/VFL
+ *
+ * GtkConstraintLayout allows defining constraints using a
+ * compact syntax called Visual Format Language, or VFL.
+ */
+
+#include <glib/gi18n.h>
+#include <gtk/gtk.h>
+
+G_DECLARE_FINAL_TYPE (VflGrid, vfl_grid, VFL, GRID, GtkWidget)
+
+struct _VflGrid
+{
+  GtkWidget parent_instance;
+
+  GtkWidget *button1, *button2;
+  GtkWidget *button3;
+};
+
+G_DEFINE_TYPE (VflGrid, vfl_grid, GTK_TYPE_WIDGET)
+
+static void
+vfl_grid_destroy (GtkWidget *widget)
+{
+  VflGrid *self = VFL_GRID (widget);
+
+  g_clear_pointer (&self->button1, gtk_widget_destroy);
+  g_clear_pointer (&self->button2, gtk_widget_destroy);
+  g_clear_pointer (&self->button3, gtk_widget_destroy);
+
+  GTK_WIDGET_CLASS (vfl_grid_parent_class)->destroy (widget);
+}
+
+static void
+vfl_grid_class_init (VflGridClass *klass)
+{
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  widget_class->destroy = vfl_grid_destroy;
+
+  gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_CONSTRAINT_LAYOUT);
+}
+
+/* Layout:
+ *
+ *   +-----------------------------+
+ *   | +-----------+ +-----------+ |
+ *   | |  Child 1  | |  Child 2  | |
+ *   | +-----------+ +-----------+ |
+ *   | +-------------------------+ |
+ *   | |         Child 3         | |
+ *   | +-------------------------+ |
+ *   +-----------------------------+
+ *
+ * Constraints:
+ *
+ *   super.start = child1.start - 8
+ *   child1.width = child2.width
+ *   child1.end = child2.start - 12
+ *   child2.end = super.end - 8
+ *   super.start = child3.start - 8
+ *   child3.end = super.end - 8
+ *   super.top = child1.top - 8
+ *   super.top = child2.top - 8
+ *   child1.bottom = child3.top - 12
+ *   child2.bottom = child3.top - 12
+ *   child3.height = child1.height
+ *   child3.height = child2.height
+ *   child3.bottom = super.bottom - 8
+ *
+ * Visual format:
+ *
+ *   H:|-8-[view1(==view2)-12-[view2]-8-|
+ *   H:|-8-[view3]-8-|
+ *   V:|-8-[view1]-12-[view3(==view1)]-8-|
+ *   V:|-8-[view2]-12-[view3(==view2)]-8-|
+ */
+static void
+build_constraints (VflGrid          *self,
+                   GtkConstraintLayout *manager)
+{
+  const char * const vfl[] = {
+    "H:|-[button1(==button2)]-12-[button2]-|",
+    "H:|-[button3]-|",
+    "V:|-[button1]-12-[button3(==button1)]-|",
+    "V:|-[button2]-12-[button3(==button2)]-|",
+  };
+  GError *error = NULL;
+
+  gtk_constraint_layout_add_constraints_from_description (manager, vfl, G_N_ELEMENTS (vfl),
+                                                          8, 8,
+                                                          &error,
+                                                          "button1", self->button1,
+                                                          "button2", self->button2,
+                                                          "button3", self->button3,
+                                                          NULL);
+  if (error != NULL)
+    {
+      g_printerr ("VFL parsing error:\n%s", error->message);
+      g_error_free (error);
+    }
+}
+
+static void
+vfl_grid_init (VflGrid *self)
+{
+  GtkWidget *widget = GTK_WIDGET (self);
+
+  self->button1 = gtk_button_new_with_label ("Child 1");
+  gtk_widget_set_parent (self->button1, widget);
+  gtk_widget_set_name (self->button1, "button1");
+
+  self->button2 = gtk_button_new_with_label ("Child 2");
+  gtk_widget_set_parent (self->button2, widget);
+  gtk_widget_set_name (self->button2, "button2");
+
+  self->button3 = gtk_button_new_with_label ("Child 3");
+  gtk_widget_set_parent (self->button3, widget);
+  gtk_widget_set_name (self->button3, "button3");
+
+  GtkLayoutManager *manager = gtk_widget_get_layout_manager (GTK_WIDGET (self));
+  build_constraints (self, GTK_CONSTRAINT_LAYOUT (manager));
+}
+
+GtkWidget *
+do_constraints3 (GtkWidget *do_widget)
+{
+ static GtkWidget *window;
+
+ if (!window)
+   {
+     GtkWidget *header, *box, *grid, *button;
+
+     window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+     gtk_window_set_display (GTK_WINDOW (window), gtk_widget_get_display (do_widget));
+
+     header = gtk_header_bar_new ();
+     gtk_header_bar_set_title (GTK_HEADER_BAR (header), "Constraints");
+     gtk_header_bar_set_show_title_buttons (GTK_HEADER_BAR (header), FALSE);
+     gtk_window_set_titlebar (GTK_WINDOW (window), header);
+     g_signal_connect (window, "destroy",
+                       G_CALLBACK (gtk_widget_destroyed), &window);
+
+     box = gtk_box_new (GTK_ORIENTATION_VERTICAL, 12);
+     gtk_container_add (GTK_CONTAINER (window), box);
+
+     grid = g_object_new (vfl_grid_get_type (), NULL);
+     gtk_widget_set_hexpand (grid, TRUE);
+     gtk_widget_set_vexpand (grid, TRUE);
+     gtk_container_add (GTK_CONTAINER (box), grid);
+
+     button = gtk_button_new_with_label ("Close");
+     gtk_container_add (GTK_CONTAINER (box), button);
+     gtk_widget_set_hexpand (grid, TRUE);
+     g_signal_connect_swapped (button, "clicked",
+                               G_CALLBACK (gtk_widget_destroy), window);
+   }
+
+ if (!gtk_widget_get_visible (window))
+   gtk_widget_show (window);
+ else
+   gtk_widget_destroy (window);
+
+ return window;
+}
@@ -150,6 +150,9 @@
    <file>clipboard.c</file>
    <file>colorsel.c</file>
    <file>combobox.c</file>
+    <file>constraints.c</file>
+    <file>constraints2.c</file>
+    <file>constraints3.c</file>
    <file>css_accordion.c</file>
    <file>css_basics.c</file>
    <file>css_blendmodes.c</file>
@@ -8,6 +8,9 @@ demos = files([
  'clipboard.c',
  'colorsel.c',
  'combobox.c',
+  'constraints.c',
+  'constraints2.c',
+  'constraints3.c',
  'css_accordion.c',
  'css_basics.c',
  'css_blendmodes.c',
@@ -1,3 +1,4 @@
+subdir('constraint-editor')
 subdir('gtk-demo')
 subdir('icon-browser')
 subdir('node-editor')
@@ -1707,7 +1707,7 @@ activate (GApplication *app)
  gtk_css_provider_load_from_resource (provider, "/org/gtk/WidgetFactory4/widget-factory.css");
  gtk_style_context_add_provider_for_display (gdk_display_get_default (),
                                              GTK_STYLE_PROVIDER (provider),
-                                              GTK_STYLE_PROVIDER_PRIORITY_USER);
+                                              GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
  g_object_unref (provider);

  builder = gtk_builder_new_from_resource ("/org/gtk/WidgetFactory4/widget-factory.ui");
@@ -99,7 +99,7 @@ if wayland_enabled
  src_dir += [ gdkwayland_inc ]
 endif

-if get_option('documentation')
+if get_option('gtk_doc')
  configure_file(input: 'version.xml.in', output: 'version.xml', configuration: version_conf)

  gnome.gtkdoc('gdk4',
@@ -34,7 +34,7 @@ private_headers = [
 images = [
 ]

-if get_option('documentation')
+if get_option('gtk_doc')
  configure_file(input: 'version.xml.in', output: 'version.xml', configuration: version_conf)

  gnome.gtkdoc('gsk4',
@@ -355,8 +355,8 @@ How to compile GTK itself
          </group>
          <sbr/>
          <group>
-            <arg choice="plain">-Ddocumentation=true</arg>
-            <arg choice="plain">-Ddocumentation=false</arg>
+            <arg choice="plain">-Dgtk_doc=true</arg>
+            <arg choice="plain">-Dgtk_doc=false</arg>
          </group>
          <sbr/>
          <group>
@@ -382,7 +382,7 @@ How to compile GTK itself
      </formalpara>

      <formalpara>
-        <title><systemitem>documentation</systemitem> and
+        <title><systemitem>gtk_doc</systemitem> and
          <systemitem>man-pages</systemitem></title>

        <para>
@@ -394,7 +394,7 @@ How to compile GTK itself
          <application>gtk-doc</application> installed and
          are modifying GTK, you may want to enable
          <application>gtk-doc</application> support by passing
-          in <systemitem>documentation</systemitem>.
+          in <systemitem>gtk_doc</systemitem>.
        </para>
        <para>
          Additionally, some tools provided by GTK have their own
@@ -109,6 +109,9 @@
      <xi:include href="xml/gtkcustomlayout.xml" />
      <xi:include href="xml/gtkfixedlayout.xml" />
      <xi:include href="xml/gtkgridlayout.xml" />
+      <xi:include href="xml/gtkconstraintlayout.xml" />
+      <xi:include href="xml/gtkconstraint.xml" />
+      <xi:include href="xml/gtkconstraintguide.xml" />
    </chapter>

    <chapter id="DisplayWidgets">
@@ -7287,3 +7287,87 @@ gtk_grid_layout_get_type
 GTK_TYPE_GRID_LAYOUT_CHILD
 gtk_grid_layout_child_get_type
 </SECTION>
+
+<SECTION>
+<FILE>gtkconstraint</FILE>
+GtkConstraint
+GtkConstraintTarget
+
+gtk_constraint_new
+gtk_constraint_new_constant
+gtk_constraint_get_target
+GtkConstraintAttribute
+gtk_constraint_get_target_attribute
+GtkConstraintRelation
+gtk_constraint_get_relation
+gtk_constraint_get_source
+gtk_constraint_get_source_attribute
+gtk_constraint_get_multiplier
+gtk_constraint_get_constant
+GtkConstraintStrength
+gtk_constraint_get_strength
+gtk_constraint_is_required
+gtk_constraint_is_attached
+gtk_constraint_is_constant
+
+<SUBSECTION Standard>
+GTK_TYPE_CONSTRAINT
+gtk_constraint_get_type
+GTK_TYPE_CONSTRAINT_TARGET
+gtk_constraint_target_get_type
+</SECTION>
+
+<SECTION>
+<FILE>gtkconstraintlayout</FILE>
+GtkConstraintLayout
+GtkConstraintLayoutChild
+GtkConstraintVflParserError
+
+gtk_constraint_layout_new
+
+<SUBSECTION Constraints>
+gtk_constraint_layout_add_constraint
+gtk_constraint_layout_remove_constraint
+gtk_constraint_layout_remove_all_constraints
+
+<SUBSECTION Guides>
+gtk_constraint_layout_add_guide
+gtk_constraint_layout_remove_guide
+
+<SUBSECTION VFL>
+gtk_constraint_layout_add_constraints_from_description
+gtk_constraint_layout_add_constraints_from_descriptionv
+
+<SUBSECTION>
+gtk_constraint_layout_observe_constraints
+gtk_constraint_layout_observe_guides
+
+<SUBSECTION Standard>
+GTK_TYPE_CONSTRAINT_LAYOUT
+gtk_constraint_layout_get_type
+GTK_TYPE_CONSTRAINT_LAYOUT_CHILD
+gtk_constraint_layout_child_get_type
+GTK_CONSTRAINT_VFL_PARSER_ERROR
+gtk_constraint_vfl_parser_error_quark
+</SECTION>
+
+<SECTION>
+<FILE>gtkconstraintguide</FILE>
+GtkConstraintGuide
+
+gtk_constraint_guide_new
+gtk_constraint_guide_set_name
+gtk_constraint_guide_get_name
+gtk_constraint_guide_set_strength
+gtk_constraint_guide_get_strength
+gtk_constraint_guide_set_min_size
+gtk_constraint_guide_get_min_size
+gtk_constraint_guide_set_nat_size
+gtk_constraint_guide_get_nat_size
+gtk_constraint_guide_set_max_size
+gtk_constraint_guide_get_max_size
+
+<SUBSECTION Standard>
+GTK_TYPE_CONSTRAINT_GUIDE
+gtk_constraint_guide_get_tyoe
+</SECTION>
@@ -49,6 +49,10 @@ gtk_color_chooser_dialog_get_type
 gtk_color_chooser_widget_get_type
 gtk_combo_box_get_type
 gtk_combo_box_text_get_type
+gtk_constraint_get_type
+gtk_constraint_guide_get_type
+gtk_constraint_layout_get_type
+gtk_constraint_target_get_type
 gtk_container_get_type
 gtk_css_provider_get_type
 gtk_dialog_get_type
@@ -23,6 +23,13 @@ private_headers = [
  'gtkcolorswatchprivate.h',
  'gtkcomboboxprivate.h',
  'gtkcontainerprivate.h',
+  'gtkconstraintexpressionprivate.h',
+  'gtkconstraintguideprivate.h',
+  'gtkconstraintlayoutprivate.h',
+  'gtkconstraintprivate.h',
+  'gtkconstraintsolverprivate.h',
+  'gtkconstrainttypesprivate.h',
+  'gtkconstraintvflparserprivate.h',
  'gtkcssanimatedstyleprivate.h',
  'gtkcssanimationprivate.h',
  'gtkcssarrayvalueprivate.h',
@@ -394,7 +401,7 @@ else
  types_conf.set('DISABLE_ON_QUARTZ', '')
 endif

-if get_option('documentation')
+if get_option('gtk_doc')
  configure_file(input: 'version.xml.in', output: 'version.xml', configuration: version_conf)
  configure_file(input: 'getting_started.xml.in', output: 'getting_started.xml', configuration: src_dir_conf)

@@ -1,4 +1,4 @@
-if get_option('documentation')
+if get_option('gtk_doc')
  glib_prefix = dependency('glib-2.0').get_pkgconfig_variable('prefix')
  glib_docpath = join_paths(glib_prefix, 'share', 'gtk-doc', 'html')

@@ -1,4 +1,4 @@
-if x11_enabled and get_option('documentation')
+if x11_enabled and get_option('gtk_doc')
  doc_shooter_sources = [
    'shadow.c',
    'shooter.c',
@@ -808,7 +808,8 @@ upload_texture (GskGLRenderer *self,
  int texture_id;

  if (texture->width <= 128 &&
-      texture->height <= 128)
+      texture->height <= 128 &&
+      !GDK_IS_GL_TEXTURE (texture))
    {
      graphene_rect_t trect;

@@ -943,11 +944,9 @@ render_transform_node (GskGLRenderer   *self,
    case GSK_TRANSFORM_CATEGORY_2D:
    default:
      {
-        graphene_matrix_t mat;

        if (node_supports_transform (child))
          {
-            gsk_transform_to_matrix (node_transform, &mat);
            ops_push_modelview (builder, node_transform);
            gsk_gl_renderer_add_render_ops (self, child, builder);
            ops_pop_modelview (builder);
@@ -972,7 +971,6 @@ render_transform_node (GskGLRenderer   *self,
                               &region, &is_offscreen,
                               RESET_CLIP | RESET_OPACITY);

-            gsk_transform_to_matrix (node_transform, &mat);
            ops_push_modelview (builder, node_transform);
            ops_set_texture (builder, region.texture_id);
            ops_set_program (builder, &self->blit_program);
@@ -339,9 +339,12 @@ ops_set_modelview_internal (RenderOpBuilder *builder,
  RenderOp op;
  graphene_matrix_t matrix;

+#if 0
+  XXX This is not possible if we want pop() to work.
  if (builder->current_program &&
      gsk_transform_equal (builder->current_program_state->modelview, transform))
    return;
+#endif

  gsk_transform_to_matrix (transform, &matrix);

@@ -1690,11 +1690,26 @@ gsk_transform_transform_bounds (GskTransform          *self,
      }
    break;

+    case GSK_TRANSFORM_CATEGORY_2D_AFFINE:
+      {
+        float dx, dy, scale_x, scale_y;
+
+        gsk_transform_to_affine (self, &scale_x, &scale_y, &dx, &dy);
+
+        *out_rect = *rect;
+        out_rect->origin.x *= scale_x;
+        out_rect->origin.y *= scale_y;
+        out_rect->size.width *= scale_x;
+        out_rect->size.height *= scale_y;
+        out_rect->origin.x += dx;
+        out_rect->origin.y += dy;
+      }
+    break;
+
    case GSK_TRANSFORM_CATEGORY_UNKNOWN:
    case GSK_TRANSFORM_CATEGORY_ANY:
    case GSK_TRANSFORM_CATEGORY_3D:
    case GSK_TRANSFORM_CATEGORY_2D:
-    case GSK_TRANSFORM_CATEGORY_2D_AFFINE:
    default:
      {
        graphene_matrix_t mat;
@@ -1886,18 +1901,43 @@ gsk_transform_parser_parse (GtkCssParser  *parser,

          transform = gsk_transform_translate_3d (transform, &GRAPHENE_POINT3D_INIT (0.f, 0.f, f[0]));
        }
-#if 0
-      /* FIXME: add these */
      else if (gtk_css_token_is_function (token, "skew"))
        {
+          graphene_matrix_t matrix;
+
+          if (!gtk_css_parser_consume_function (parser, 2, 2, gsk_transform_parse_float, f))
+            goto fail;
+
+          f[0] = f[0] / 180.0 * G_PI;
+          f[1] = f[1] / 180.0 * G_PI;
+
+          graphene_matrix_init_skew (&matrix, f[0], f[1]);
+          transform = gsk_transform_matrix (transform, &matrix);
        }
      else if (gtk_css_token_is_function (token, "skewX"))
        {
+          graphene_matrix_t matrix;
+
+          if (!gtk_css_parser_consume_function (parser, 1, 1, gsk_transform_parse_float, f))
+            goto fail;
+
+          f[0] = f[0] / 180.0 * G_PI;
+
+          graphene_matrix_init_skew (&matrix, f[0], 0);
+          transform = gsk_transform_matrix (transform, &matrix);
        }
      else if (gtk_css_token_is_function (token, "skewY"))
        {
+          graphene_matrix_t matrix;
+
+          if (!gtk_css_parser_consume_function (parser, 1, 1, gsk_transform_parse_float, f))
+            goto fail;
+
+          f[0] = f[0] / 180.0 * G_PI;
+
+          graphene_matrix_init_skew (&matrix, 0, f[0]);
+          transform = gsk_transform_matrix (transform, &matrix);
        }
-#endif
      else
        {
          break;
@@ -82,6 +82,8 @@
 #include <gtk/gtkcolorutils.h>
 #include <gtk/gtkcombobox.h>
 #include <gtk/gtkcomboboxtext.h>
+#include <gtk/gtkconstraintlayout.h>
+#include <gtk/gtkconstraint.h>
 #include <gtk/gtkcontainer.h>
 #include <gtk/gtkcssprovider.h>
 #include <gtk/gtkcustomlayout.h>
@@ -561,13 +561,6 @@ prop_actions_connect (GtkActionMuxer *muxer)
    }
 }

-static void
-prop_actions_disconnect (GtkActionMuxer *muxer)
-{
-  if (muxer->widget)
-    g_signal_handlers_disconnect_by_func (muxer->widget,
-                                          prop_action_notify, muxer);
-}

 static gboolean
 gtk_action_muxer_query_action (GActionGroup        *action_group,
@@ -819,8 +812,6 @@ gtk_action_muxer_dispose (GObject *object)
 {
  GtkActionMuxer *muxer = GTK_ACTION_MUXER (object);

-  prop_actions_disconnect (muxer);
-
  if (muxer->parent)
  {
    g_signal_handlers_disconnect_by_func (muxer->parent, gtk_action_muxer_action_added_to_parent, muxer);
@@ -0,0 +1,614 @@
+/* gtkconstraint.c: Constraint between two widgets
+ * Copyright 2019  GNOME Foundation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Emmanuele Bassi
+ */
+
+/**
+ * SECTION:gtkconstraint
+ * @Title: GtkConstraint
+ * @Short_description: The description of a constraint
+ *
+ * #GtkConstraint describes a constraint between an attribute on a widget
+ * and another attribute on another widget, expressed as a linear equation
+ * like:
+ *
+ * |[
+ *   target.attr1 = source.attr2 × multiplier + constant
+ * ]|
+ *
+ * Each #GtkConstraint is part of a system that will be solved by a
+ * #GtkConstraintLayout in order to allocate and position each child widget.
+ *
+ * The source and target widgets, as well as their attributes, of a
+ * #GtkConstraint instance are immutable after creation.
+ */
+
+#include "config.h"
+
+#include "gtkconstraintprivate.h"
+#include "gtkconstraintsolverprivate.h"
+#include "gtkintl.h"
+#include "gtktypebuiltins.h"
+#include "gtkwidget.h"
+
+enum {
+  PROP_TARGET = 1,
+  PROP_TARGET_ATTRIBUTE,
+  PROP_RELATION,
+  PROP_SOURCE,
+  PROP_SOURCE_ATTRIBUTE,
+  PROP_MULTIPLIER,
+  PROP_CONSTANT,
+  PROP_STRENGTH,
+
+  N_PROPERTIES
+};
+
+static GParamSpec *obj_props[N_PROPERTIES];
+
+G_DEFINE_TYPE (GtkConstraint, gtk_constraint, G_TYPE_OBJECT)
+
+static void
+gtk_constraint_set_property (GObject      *gobject,
+                             guint         prop_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+  GtkConstraint *self = GTK_CONSTRAINT (gobject);
+
+  switch (prop_id)
+    {
+    case PROP_TARGET:
+      self->target = g_value_get_object (value);
+      break;
+
+    case PROP_TARGET_ATTRIBUTE:
+      self->target_attribute = g_value_get_enum (value);
+      break;
+
+    case PROP_RELATION:
+      self->relation = g_value_get_enum (value);
+      break;
+
+    case PROP_SOURCE:
+      self->source = g_value_get_object (value);
+      break;
+
+    case PROP_SOURCE_ATTRIBUTE:
+      self->source_attribute = g_value_get_enum (value);
+      break;
+
+    case PROP_MULTIPLIER:
+      self->multiplier = g_value_get_double (value);
+      break;
+
+    case PROP_CONSTANT:
+      self->constant = g_value_get_double (value);
+      break;
+
+    case PROP_STRENGTH:
+      self->strength = g_value_get_int (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_constraint_get_property (GObject    *gobject,
+                             guint       prop_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+  GtkConstraint *self = GTK_CONSTRAINT (gobject);
+
+  switch (prop_id)
+    {
+    case PROP_TARGET:
+      g_value_set_object (value, self->target);
+      break;
+
+    case PROP_TARGET_ATTRIBUTE:
+      g_value_set_enum (value, self->target_attribute);
+      break;
+
+    case PROP_RELATION:
+      g_value_set_enum (value, self->relation);
+      break;
+
+    case PROP_SOURCE:
+      g_value_set_object (value, self->source);
+      break;
+
+    case PROP_SOURCE_ATTRIBUTE:
+      g_value_set_enum (value, self->source_attribute);
+      break;
+
+    case PROP_MULTIPLIER:
+      g_value_set_double (value, self->multiplier);
+      break;
+
+    case PROP_CONSTANT:
+      g_value_set_double (value, self->constant);
+      break;
+
+    case PROP_STRENGTH:
+      g_value_set_int (value, self->strength);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_constraint_finalize (GObject *gobject)
+{
+  GtkConstraint *self = GTK_CONSTRAINT (gobject);
+
+  gtk_constraint_detach (self);
+
+  G_OBJECT_CLASS (gtk_constraint_parent_class)->finalize (gobject);
+}
+
+static void
+gtk_constraint_class_init (GtkConstraintClass *klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  gobject_class->set_property = gtk_constraint_set_property;
+  gobject_class->get_property = gtk_constraint_get_property;
+  gobject_class->finalize = gtk_constraint_finalize;
+
+  /**
+   * GtkConstraint:target:
+   *
+   * The target of the constraint.
+   *
+   * The constraint will set the #GtkConstraint:target-attribute of the
+   * target using the #GtkConstraint:source-attribute of the source
+   * widget.
+   */
+  obj_props[PROP_TARGET] =
+    g_param_spec_object ("target",
+                         P_("Target"),
+                         P_("The target of the constraint"),
+                         GTK_TYPE_CONSTRAINT_TARGET,
+                         G_PARAM_READWRITE |
+                         G_PARAM_STATIC_STRINGS |
+                         G_PARAM_CONSTRUCT_ONLY);
+  /**
+   * GtkConstraint:target-attribute:
+   *
+   * The attribute of the #GtkConstraint:target set by the constraint.
+   */
+  obj_props[PROP_TARGET_ATTRIBUTE] =
+    g_param_spec_enum ("target-attribute",
+                       P_("Target Attribute"),
+                       P_("The attribute of the target set by the constraint"),
+                       GTK_TYPE_CONSTRAINT_ATTRIBUTE,
+                       GTK_CONSTRAINT_ATTRIBUTE_NONE,
+                       G_PARAM_READWRITE |
+                       G_PARAM_STATIC_STRINGS |
+                       G_PARAM_CONSTRUCT_ONLY);
+  /**
+   * GtkConstraint:relation:
+   *
+   * The order relation between the terms of the constraint.
+   */
+  obj_props[PROP_RELATION] =
+    g_param_spec_enum ("relation",
+                       P_("Relation"),
+                       P_("The relation between the source and target attributes"),
+                       GTK_TYPE_CONSTRAINT_RELATION,
+                       GTK_CONSTRAINT_RELATION_EQ,
+                       G_PARAM_READWRITE |
+                       G_PARAM_STATIC_STRINGS |
+                       G_PARAM_CONSTRUCT_ONLY);
+  /**
+   * GtkConstraint:source:
+   *
+   * The source of the constraint.
+   *
+   * The constraint will set the #GtkConstraint:target-attribute of the
+   * target using the #GtkConstraint:source-attribute of the source.
+   */
+  obj_props[PROP_SOURCE] =
+    g_param_spec_object ("source",
+                         P_("Source"),
+                         P_("The source of the constraint"),
+                         GTK_TYPE_CONSTRAINT_TARGET,
+                         G_PARAM_READWRITE |
+                         G_PARAM_STATIC_STRINGS |
+                         G_PARAM_CONSTRUCT_ONLY);
+  /**
+   * GtkConstraint:source-attribute:
+   *
+   * The attribute of the #GtkConstraint:source read by the constraint.
+   */
+  obj_props[PROP_SOURCE_ATTRIBUTE] =
+    g_param_spec_enum ("source-attribute",
+                       P_("Source Attribute"),
+                       P_("The attribute of the source widget set by the constraint"),
+                       GTK_TYPE_CONSTRAINT_ATTRIBUTE,
+                       GTK_CONSTRAINT_ATTRIBUTE_NONE,
+                       G_PARAM_READWRITE |
+                       G_PARAM_STATIC_STRINGS |
+                       G_PARAM_CONSTRUCT_ONLY);
+  /**
+   * GtkConstraint:multiplier:
+   *
+   * The multiplication factor to be applied to the
+   * #GtkConstraint:source-attribue.
+   */
+  obj_props[PROP_MULTIPLIER] =
+    g_param_spec_double ("multiplier",
+                         P_("Multiplier"),
+                         P_("The multiplication factor to be applied to the source attribute"),
+                         -G_MAXDOUBLE, G_MAXDOUBLE, 1.0,
+                         G_PARAM_READWRITE |
+                         G_PARAM_STATIC_STRINGS |
+                         G_PARAM_CONSTRUCT_ONLY);
+  /**
+   * GtkConstraint:constant:
+   *
+   * The constant value to be added to the #GtkConstraint:source-attribute.
+   */
+  obj_props[PROP_CONSTANT] =
+    g_param_spec_double ("constant",
+                         P_("Constant"),
+                         P_("The constant to be added to the source attribute"),
+                         -G_MAXDOUBLE, G_MAXDOUBLE, 0.0,
+                         G_PARAM_READWRITE |
+                         G_PARAM_STATIC_STRINGS |
+                         G_PARAM_CONSTRUCT_ONLY);
+  /**
+   * GtkConstraint:strength:
+   *
+   * The strength of the constraint.
+   *
+   * The strength can be expressed either using one of the symbolic values
+   * of the #GtkConstraintStrength enumeration, or any positive integer
+   * value.
+   */
+  obj_props[PROP_STRENGTH] =
+    g_param_spec_int ("strength",
+                      P_("Strength"),
+                      P_("The strength of the constraint"),
+                      0, GTK_CONSTRAINT_STRENGTH_REQUIRED,
+                      GTK_CONSTRAINT_STRENGTH_REQUIRED,
+                      G_PARAM_READWRITE |
+                      G_PARAM_STATIC_STRINGS |
+                      G_PARAM_CONSTRUCT_ONLY);
+
+  g_object_class_install_properties (gobject_class, N_PROPERTIES, obj_props);
+}
+
+static void
+gtk_constraint_init (GtkConstraint *self)
+{
+  self->multiplier = 1.0;
+  self->constant = 0.0;
+
+  self->target_attribute = GTK_CONSTRAINT_ATTRIBUTE_NONE;
+  self->source_attribute = GTK_CONSTRAINT_ATTRIBUTE_NONE;
+  self->relation = GTK_CONSTRAINT_RELATION_EQ;
+  self->strength = GTK_CONSTRAINT_STRENGTH_REQUIRED;
+}
+
+/**
+ * gtk_constraint_new:
+ * @target: (nullable) (type GtkConstraintTarget): a #GtkConstraintTarget
+ * @target_attribute: the attribute of @target to be set
+ * @relation: the relation equivalence between @target_attribute and @source_attribute
+ * @source: (nullable) (type GtkConstraintTarget): a #GtkConstraintTarget
+ * @source_attribute: the attribute of @source to be read
+ * @multiplier: a multiplication factor to be applied to @source_attribute
+ * @constant: a constant factor to be added to @source_attribute
+ * @strength: the strength of the constraint
+ *
+ * Creates a new #GtkConstraint representing a relation between a layout
+ * attribute on a source and a layout attribute on a target.
+ *
+ * Returns: the newly created #GtkConstraint
+ */
+GtkConstraint *
+gtk_constraint_new (gpointer                target,
+                    GtkConstraintAttribute  target_attribute,
+                    GtkConstraintRelation   relation,
+                    gpointer                source,
+                    GtkConstraintAttribute  source_attribute,
+                    double                  multiplier,
+                    double                  constant,
+                    int                     strength)
+{
+  g_return_val_if_fail (target == NULL || GTK_IS_CONSTRAINT_TARGET (target), NULL);
+  g_return_val_if_fail (source == NULL || GTK_IS_CONSTRAINT_TARGET (source), NULL);
+
+  return g_object_new (GTK_TYPE_CONSTRAINT,
+                       "target", target,
+                       "target-attribute", target_attribute,
+                       "relation", relation,
+                       "source", source,
+                       "source-attribute", source_attribute,
+                       "multiplier", multiplier,
+                       "constant", constant,
+                       "strength", strength,
+                       NULL);
+}
+
+/**
+ * gtk_constraint_new_constant:
+ * @target: (nullable) (type GtkConstraintTarget): a #GtkConstraintTarget
+ * @target_attribute: the attribute of @target to be set
+ * @relation: the relation equivalence between @target_attribute and @constant
+ * @constant: a constant factor to be set on @target_attribute
+ * @strength: the strength of the constraint
+ *
+ * Creates a new #GtkConstraint representing a relation between a layout
+ * attribute on a target and a constant value.
+ *
+ * Returns: the newly created #GtkConstraint
+ */
+GtkConstraint *
+gtk_constraint_new_constant (gpointer                target,
+                             GtkConstraintAttribute  target_attribute,
+                             GtkConstraintRelation   relation,
+                             double                  constant,
+                             int                     strength)
+{
+  g_return_val_if_fail (target == NULL || GTK_IS_CONSTRAINT_TARGET (target), NULL);
+
+  return g_object_new (GTK_TYPE_CONSTRAINT,
+                       "target", target,
+                       "target-attribute", target_attribute,
+                       "relation", relation,
+                       "source-attribute", GTK_CONSTRAINT_ATTRIBUTE_NONE,
+                       "constant", constant,
+                       "strength", strength,
+                       NULL);
+}
+
+/**
+ * gtk_constraint_get_target:
+ * @constraint: a #GtkConstraint
+ *
+ * Retrieves the #GtkConstraintTarget used as the target for @constraint.
+ *
+ * If the #GtkConstraint:target property is set to %NULL, the @constraint
+ * will use the #GtkConstraintLayout's widget.
+ *
+ * Returns: (transfer none) (nullable): a #GtkConstraintTarget
+ */
+GtkConstraintTarget *
+gtk_constraint_get_target (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), NULL);
+
+  return constraint->target;
+}
+
+/**
+ * gtk_constraint_get_target_attribute:
+ * @constraint: a #GtkConstraint
+ *
+ * Retrieves the attribute of the target to be set by the @constraint.
+ *
+ * Returns: the target's attribute
+ */
+GtkConstraintAttribute
+gtk_constraint_get_target_attribute (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), GTK_CONSTRAINT_ATTRIBUTE_NONE);
+
+  return constraint->target_attribute;
+}
+
+/**
+ * gtk_constraint_get_source:
+ * @constraint: a #GtkConstraint
+ *
+ * Retrieves the #GtkConstraintTarget used as the source for @constraint.
+ *
+ * If the #GtkConstraint:source property is set to %NULL, the @constraint
+ * will use the #GtkConstraintLayout's widget.
+ *
+ * Returns: (transfer none) (nullable): a #GtkConstraintTarget
+ */
+GtkConstraintTarget *
+gtk_constraint_get_source (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), NULL);
+
+  return constraint->source;
+}
+
+/**
+ * gtk_constraint_get_source_attribute:
+ * @constraint: a #GtkConstraint
+ *
+ * Retrieves the attribute of the source to be read by the @constraint.
+ *
+ * Returns: the target's attribute
+ */
+GtkConstraintAttribute
+gtk_constraint_get_source_attribute (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), GTK_CONSTRAINT_ATTRIBUTE_NONE);
+
+  return constraint->source_attribute;
+}
+
+/**
+ * gtk_constraint_get_relation:
+ * @constraint: a #GtkConstraint
+ *
+ * The order relation between the terms of the @constraint.
+ *
+ * Returns: a #GtkConstraintRelation value
+ */
+GtkConstraintRelation
+gtk_constraint_get_relation (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), GTK_CONSTRAINT_RELATION_EQ);
+
+  return constraint->relation;
+}
+
+/**
+ * gtk_constraint_get_multiplier:
+ * @constraint: a #GtkConstraint
+ *
+ * Retrieves the multiplication factor applied to the source
+ * attribute's value.
+ *
+ * Returns: a multiplication factor
+ */
+double
+gtk_constraint_get_multiplier (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), 1.0);
+
+  return constraint->multiplier;
+}
+
+/**
+ * gtk_constraint_get_constant:
+ * @constraint: a #GtkConstraint
+ *
+ * Retrieves the constant factor added to the source attributes' value.
+ *
+ * Returns: a constant factor
+ */
+double
+gtk_constraint_get_constant (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), 0.0);
+
+  return constraint->constant;
+}
+
+/**
+ * gtk_constraint_get_strength:
+ * @constraint: a #GtkConstraint
+ *
+ * Retrieves the strength of the constraint.
+ *
+ * Returns: the strength of the constraint
+ */
+int
+gtk_constraint_get_strength (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  return constraint->strength;
+}
+
+/**
+ * gtk_constraint_is_required:
+ * @constraint: a #GtkConstraint
+ *
+ * Checks whether the @constraint is a required relation for solving the
+ * constraint layout.
+ *
+ * Returns: %TRUE if the constraint is required
+ */
+gboolean
+gtk_constraint_is_required (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), FALSE);
+
+  return constraint->strength == GTK_CONSTRAINT_STRENGTH_REQUIRED;
+}
+
+/**
+ * gtk_constraint_is_attached:
+ * @constraint: a #GtkConstraint
+ *
+ * Checks whether the @constraint is attached to a #GtkConstraintLayout,
+ * and it is contributing to the layout.
+ *
+ * Returns: %TRUE if the constraint is attached
+ */
+gboolean
+gtk_constraint_is_attached (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), FALSE);
+
+  return constraint->constraint_ref != NULL;
+}
+
+/**
+ * gtk_constraint_is_constant:
+ * @constraint: a #GtkConstraint
+ *
+ * Checks whether the @constraint describes a relation between an attribute
+ * on the #GtkConstraint:target-widget and a constant value.
+ *
+ * Returns: %TRUE if the constraint is a constant relation
+ */
+gboolean
+gtk_constraint_is_constant (GtkConstraint *constraint)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT (constraint), FALSE);
+
+  return constraint->source == NULL &&
+         constraint->source_attribute == GTK_CONSTRAINT_ATTRIBUTE_NONE;
+}
+
+void
+gtk_constraint_attach (GtkConstraint       *constraint,
+                       GtkConstraintSolver *solver,
+                       GtkConstraintRef    *ref)
+{
+  g_return_if_fail (GTK_IS_CONSTRAINT (constraint));
+  g_return_if_fail (GTK_IS_CONSTRAINT_SOLVER (solver));
+  g_return_if_fail (ref != NULL);
+
+  constraint->constraint_ref = ref;
+  constraint->solver = solver;
+}
+
+void
+gtk_constraint_detach (GtkConstraint *constraint)
+{
+  g_return_if_fail (GTK_IS_CONSTRAINT (constraint));
+
+  if (constraint->constraint_ref == NULL)
+    return;
+
+  gtk_constraint_solver_remove_constraint (constraint->solver, constraint->constraint_ref);
+  constraint->constraint_ref = NULL;
+  constraint->solver = NULL;
+}
+
+typedef struct _GtkConstraintTargetInterface GtkConstraintTargetInterface;
+
+struct _GtkConstraintTargetInterface
+{
+  GTypeInterface g_iface;
+};
+
+G_DEFINE_INTERFACE (GtkConstraintTarget, gtk_constraint_target, G_TYPE_OBJECT)
+
+static void
+gtk_constraint_target_default_init (GtkConstraintTargetInterface *iface)
+{
+}
@@ -0,0 +1,100 @@
+/* gtkconstraint.h: Constraint between two widgets
+ * Copyright 2019  GNOME Foundation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Emmanuele Bassi
+ */
+
+#pragma once
+
+#include <gtk/gtktypes.h>
+#include <gtk/gtkenums.h>
+
+G_BEGIN_DECLS
+
+typedef struct _GtkConstraintTarget GtkConstraintTarget;
+
+#define GTK_TYPE_CONSTRAINT_TARGET (gtk_constraint_target_get_type ())
+
+/**
+ * GtkConstraintTarget:
+ *
+ * The GtkConstraintTarget interface is implemented by objects that
+ * can be used as source or target in #GtkConstraints. Besides
+ * #GtkWidget, it is also implemented by #GtkConstraintGuide.
+ */
+
+GDK_AVAILABLE_IN_ALL
+G_DECLARE_INTERFACE (GtkConstraintTarget, gtk_constraint_target, GTK, CONSTRAINT_TARGET, GObject)
+
+#define GTK_TYPE_CONSTRAINT (gtk_constraint_get_type ())
+
+/**
+ * GtkConstraint:
+ *
+ * An object describing the relation between two widget attributes.
+ *
+ * All relations are in the form:
+ *
+ * |[<!-- language=plain -->
+ *   target.attr_name = source.attr_name × multiplier + constant
+ * ]|
+ *
+ * A #GtkConstraint is immutable once it's created.
+ */
+GDK_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (GtkConstraint, gtk_constraint, GTK, CONSTRAINT, GObject)
+
+GDK_AVAILABLE_IN_ALL
+GtkConstraint *         gtk_constraint_new                      (gpointer                target,
+                                                                 GtkConstraintAttribute  target_attribute,
+                                                                 GtkConstraintRelation   relation,
+                                                                 gpointer                source,
+                                                                 GtkConstraintAttribute  source_attribute,
+                                                                 double                  multiplier,
+                                                                 double                  constant,
+                                                                 int                     strength);
+GDK_AVAILABLE_IN_ALL
+GtkConstraint *         gtk_constraint_new_constant             (gpointer                target,
+                                                                 GtkConstraintAttribute  target_attribute,
+                                                                 GtkConstraintRelation   relation,
+                                                                 double                  constant,
+                                                                 int                     strength);
+
+GDK_AVAILABLE_IN_ALL
+GtkConstraintTarget *   gtk_constraint_get_target               (GtkConstraint          *constraint);
+GDK_AVAILABLE_IN_ALL
+GtkConstraintAttribute  gtk_constraint_get_target_attribute     (GtkConstraint          *constraint);
+GDK_AVAILABLE_IN_ALL
+GtkConstraintTarget *   gtk_constraint_get_source               (GtkConstraint          *constraint);
+GDK_AVAILABLE_IN_ALL
+GtkConstraintAttribute  gtk_constraint_get_source_attribute     (GtkConstraint          *constraint);
+GDK_AVAILABLE_IN_ALL
+GtkConstraintRelation   gtk_constraint_get_relation             (GtkConstraint          *constraint);
+GDK_AVAILABLE_IN_ALL
+double                  gtk_constraint_get_multiplier           (GtkConstraint          *constraint);
+GDK_AVAILABLE_IN_ALL
+double                  gtk_constraint_get_constant             (GtkConstraint          *constraint);
+GDK_AVAILABLE_IN_ALL
+int                     gtk_constraint_get_strength             (GtkConstraint          *constraint);
+
+GDK_AVAILABLE_IN_ALL
+gboolean                gtk_constraint_is_required              (GtkConstraint          *constraint);
+GDK_AVAILABLE_IN_ALL
+gboolean                gtk_constraint_is_attached              (GtkConstraint          *constraint);
+GDK_AVAILABLE_IN_ALL
+gboolean                gtk_constraint_is_constant              (GtkConstraint          *constraint);
+
+G_END_DECLS
@@ -0,0 +1,279 @@
+/* gtkconstraintequationprivate.h: Constraint expressions and variables
+ * Copyright 2019  GNOME Foundation
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Emmanuele Bassi
+ */
+
+#pragma once
+
+#include "gtkconstrainttypesprivate.h"
+
+G_BEGIN_DECLS
+
+GtkConstraintVariable *
+gtk_constraint_variable_new (const char *prefix,
+                             const char *name);
+
+GtkConstraintVariable *
+gtk_constraint_variable_new_dummy (const char *name);
+
+GtkConstraintVariable *
+gtk_constraint_variable_new_objective (const char *name);
+
+GtkConstraintVariable *
+gtk_constraint_variable_new_slack (const char *name);
+
+GtkConstraintVariable *
+gtk_constraint_variable_ref (GtkConstraintVariable *variable);
+
+void
+gtk_constraint_variable_unref (GtkConstraintVariable *variable);
+
+void
+gtk_constraint_variable_set_value (GtkConstraintVariable *variable,
+                                   double value);
+
+double
+gtk_constraint_variable_get_value (const GtkConstraintVariable *variable);
+
+char *
+gtk_constraint_variable_to_string (const GtkConstraintVariable *variable);
+
+gboolean
+gtk_constraint_variable_is_external (const GtkConstraintVariable *variable);
+
+gboolean
+gtk_constraint_variable_is_pivotable (const GtkConstraintVariable *variable);
+
+gboolean
+gtk_constraint_variable_is_restricted (const GtkConstraintVariable *variable);
+
+gboolean
+gtk_constraint_variable_is_dummy (const GtkConstraintVariable *variable);
+
+typedef struct {
+  GtkConstraintVariable *first;
+  GtkConstraintVariable *second;
+} GtkConstraintVariablePair;
+
+GtkConstraintVariablePair *
+gtk_constraint_variable_pair_new (GtkConstraintVariable *first,
+                                  GtkConstraintVariable *second);
+
+void
+gtk_constraint_variable_pair_free (GtkConstraintVariablePair *pair);
+
+typedef struct _GtkConstraintVariableSet        GtkConstraintVariableSet;
+
+GtkConstraintVariableSet *
+gtk_constraint_variable_set_new (void);
+
+void
+gtk_constraint_variable_set_free (GtkConstraintVariableSet *set);
+
+gboolean
+gtk_constraint_variable_set_add (GtkConstraintVariableSet *set,
+                                 GtkConstraintVariable *variable);
+
+gboolean
+gtk_constraint_variable_set_remove (GtkConstraintVariableSet *set,
+                                    GtkConstraintVariable *variable);
+
+gboolean
+gtk_constraint_variable_set_is_empty (GtkConstraintVariableSet *set);
+
+gboolean
+gtk_constraint_variable_set_is_singleton (GtkConstraintVariableSet *set);
+
+int
+gtk_constraint_variable_set_size (GtkConstraintVariableSet *set);
+
+typedef struct {
+  /*< private >*/
+  gpointer dummy1;
+  gpointer dummy2;
+  gint64 dummy3;
+} GtkConstraintVariableSetIter;
+
+void
+gtk_constraint_variable_set_iter_init (GtkConstraintVariableSetIter *iter,
+                                       GtkConstraintVariableSet *set);
+
+gboolean
+gtk_constraint_variable_set_iter_next (GtkConstraintVariableSetIter *iter,
+                                       GtkConstraintVariable **variable_p);
+
+GtkConstraintExpression *
+gtk_constraint_expression_new (double constant);
+
+GtkConstraintExpression *
+gtk_constraint_expression_new_from_variable (GtkConstraintVariable *variable);
+
+GtkConstraintExpression *
+gtk_constraint_expression_ref (GtkConstraintExpression *expression);
+
+void
+gtk_constraint_expression_unref (GtkConstraintExpression *expression);
+
+GtkConstraintExpression *
+gtk_constraint_expression_clone (GtkConstraintExpression *expression);
+
+void
+gtk_constraint_expression_set_constant (GtkConstraintExpression *expression,
+                                        double constant);
+double
+gtk_constraint_expression_get_constant (const GtkConstraintExpression *expression);
+
+gboolean
+gtk_constraint_expression_is_constant (const GtkConstraintExpression *expression);
+
+void
+gtk_constraint_expression_add_expression (GtkConstraintExpression *a_expr,
+                                          GtkConstraintExpression *b_expr,
+                                          double n,
+                                          GtkConstraintVariable *subject,
+                                          GtkConstraintSolver *solver);
+
+void
+gtk_constraint_expression_add_variable (GtkConstraintExpression *expression,
+                                        GtkConstraintVariable *variable,
+                                        double coefficient,
+                                        GtkConstraintVariable *subject,
+                                        GtkConstraintSolver *solver);
+
+void
+gtk_constraint_expression_remove_variable (GtkConstraintExpression *expression,
+                                           GtkConstraintVariable *variable);
+
+void
+gtk_constraint_expression_set_variable (GtkConstraintExpression *expression,
+                                        GtkConstraintVariable *variable,
+                                        double coefficient);
+
+double
+gtk_constraint_expression_get_coefficient (GtkConstraintExpression *expression,
+                                           GtkConstraintVariable *variable);
+
+char *
+gtk_constraint_expression_to_string (const GtkConstraintExpression *expression);
+
+double
+gtk_constraint_expression_new_subject (GtkConstraintExpression *expression,
+                                       GtkConstraintVariable *subject);
+
+void
+gtk_constraint_expression_change_subject (GtkConstraintExpression *expression,
+                                          GtkConstraintVariable *old_subject,
+                                          GtkConstraintVariable *new_subject);
+
+void
+gtk_constraint_expression_substitute_out (GtkConstraintExpression *expression,
+                                          GtkConstraintVariable *out_var,
+                                          GtkConstraintExpression *expr,
+                                          GtkConstraintVariable *subject,
+                                          GtkConstraintSolver *solver);
+
+GtkConstraintVariable *
+gtk_constraint_expression_get_pivotable_variable (GtkConstraintExpression *expression);
+
+GtkConstraintExpression *
+gtk_constraint_expression_plus_constant (GtkConstraintExpression *expression,
+                                         double constant);
+
+GtkConstraintExpression *
+gtk_constraint_expression_minus_constant (GtkConstraintExpression *expression,
+                                          double constant);
+
+GtkConstraintExpression *
+gtk_constraint_expression_plus_variable (GtkConstraintExpression *expression,
+                                         GtkConstraintVariable *variable);
+
+GtkConstraintExpression *
+gtk_constraint_expression_minus_variable (GtkConstraintExpression *expression,
+                                          GtkConstraintVariable *variable);
+
+GtkConstraintExpression *
+gtk_constraint_expression_multiply_by (GtkConstraintExpression *expression,
+                                       double factor);
+
+GtkConstraintExpression *
+gtk_constraint_expression_divide_by (GtkConstraintExpression *expression,
+                                     double factor);
+
+struct _GtkConstraintExpressionBuilder
+{
+  /*< private >*/
+  gpointer dummy1;
+  gpointer dummy2;
+  int dummy3;
+};
+
+void
+gtk_constraint_expression_builder_init (GtkConstraintExpressionBuilder *builder,
+                                        GtkConstraintSolver *solver);
+
+void
+gtk_constraint_expression_builder_term (GtkConstraintExpressionBuilder *builder,
+                                        GtkConstraintVariable *term);
+
+void
+gtk_constraint_expression_builder_plus (GtkConstraintExpressionBuilder *builder);
+
+void
+gtk_constraint_expression_builder_minus (GtkConstraintExpressionBuilder *builder);
+
+void
+gtk_constraint_expression_builder_divide_by (GtkConstraintExpressionBuilder *builder);
+
+void
+gtk_constraint_expression_builder_multiply_by (GtkConstraintExpressionBuilder *builder);
+
+void
+gtk_constraint_expression_builder_constant (GtkConstraintExpressionBuilder *builder,
+                                            double value);
+
+GtkConstraintExpression *
+gtk_constraint_expression_builder_finish (GtkConstraintExpressionBuilder *builder) G_GNUC_WARN_UNUSED_RESULT;
+
+/*< private >
+ * GtkConstraintExpressionIter:
+ *
+ * An iterator object for terms inside a #GtkConstraintExpression.
+ */
+typedef struct {
+  /*< private >*/
+  gpointer dummy1;
+  gpointer dummy2;
+  gint64 dummy3;
+} GtkConstraintExpressionIter;
+
+void
+gtk_constraint_expression_iter_init (GtkConstraintExpressionIter *iter,
+                                     GtkConstraintExpression *equation);
+
+gboolean
+gtk_constraint_expression_iter_next (GtkConstraintExpressionIter *iter,
+                                     GtkConstraintVariable **variable,
+                                     double *coefficient);
+
+gboolean
+gtk_constraint_expression_iter_prev (GtkConstraintExpressionIter *iter,
+                                     GtkConstraintVariable **variable,
+                                     double *coefficient);
+
+G_END_DECLS
@@ -0,0 +1,694 @@
+/* gtkconstraintguide.c: Flexible space for constraints
+ * Copyright 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Matthias Clasen
+ */
+
+/**
+ * SECTION:gtkconstraintguide
+ * @Title: GtkConstraintGuide
+ * @Short_description: An invisible constraint target
+ *
+ * A #GtkConstraintGuide is an invisible layout element that can be
+ * used by widgets inside a #GtkConstraintLayout as a source or a target
+ * of a #GtkConstraint. Guides can be used like guidelines or as
+ * flexible space.
+ *
+ * Unlike a #GtkWidget, a #GtkConstraintGuide will not be drawn.
+ */
+
+#include "config.h"
+
+#include "gtkconstraintguide.h"
+
+#include "gtkconstraintguideprivate.h"
+#include "gtkconstraintlayoutprivate.h"
+#include "gtkconstraintexpressionprivate.h"
+#include "gtkconstraintsolverprivate.h"
+
+#include "gtkdebug.h"
+#include "gtkintl.h"
+#include "gtkprivate.h"
+
+
+typedef enum {
+  MIN_WIDTH,
+  MIN_HEIGHT,
+  NAT_WIDTH,
+  NAT_HEIGHT,
+  MAX_WIDTH,
+  MAX_HEIGHT,
+  LAST_VALUE
+} GuideValue;
+
+struct _GtkConstraintGuide
+{ 
+  GObject parent_instance;
+
+  char *name;
+
+  int strength;
+
+  int values[LAST_VALUE];
+
+  GtkConstraintLayout *layout;
+
+  /* HashTable<static string, Variable>; a hash table of variables,
+   * one for each attribute; we use these to query and suggest the
+   * values for the solver. The string is static and does not need
+   * to be freed.
+   */
+  GHashTable *bound_attributes;
+
+  GtkConstraintRef *constraints[LAST_VALUE];
+};
+
+
+struct _GtkConstraintGuideClass {
+  GObjectClass parent_class;
+};
+
+enum {
+  PROP_MIN_WIDTH = 1,
+  PROP_MIN_HEIGHT,
+  PROP_NAT_WIDTH,
+  PROP_NAT_HEIGHT,
+  PROP_MAX_WIDTH,
+  PROP_MAX_HEIGHT,
+  PROP_STRENGTH,
+  PROP_NAME,
+  LAST_PROP
+};
+
+static GParamSpec *guide_props[LAST_PROP];
+
+static void
+gtk_constraint_guide_constraint_target_iface_init (GtkConstraintTargetInterface *iface)
+{
+}
+
+G_DEFINE_TYPE_WITH_CODE (GtkConstraintGuide, gtk_constraint_guide, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (GTK_TYPE_CONSTRAINT_TARGET,
+                                                gtk_constraint_guide_constraint_target_iface_init))
+
+static void
+gtk_constraint_guide_init (GtkConstraintGuide *guide)
+{
+  guide->strength = GTK_CONSTRAINT_STRENGTH_MEDIUM;
+
+  guide->values[MIN_WIDTH] = 0;
+  guide->values[MIN_HEIGHT] = 0;
+  guide->values[NAT_WIDTH] = 0;
+  guide->values[NAT_HEIGHT] = 0;
+  guide->values[MAX_WIDTH] = G_MAXINT;
+  guide->values[MAX_HEIGHT] = G_MAXINT;
+
+  guide->bound_attributes =
+    g_hash_table_new_full (g_str_hash, g_str_equal,
+                           NULL,
+                           (GDestroyNotify) gtk_constraint_variable_unref);
+}
+
+static void
+gtk_constraint_guide_update_constraint (GtkConstraintGuide *guide,
+                                        GuideValue          index)
+{
+  GtkConstraintSolver *solver;
+  GtkConstraintVariable *var;
+
+  if (!guide->layout)
+    return;
+
+  solver = gtk_constraint_layout_get_solver (guide->layout);
+  if (!solver)
+    return;
+
+  if (guide->constraints[index] != NULL)
+    {
+      gtk_constraint_solver_remove_constraint (solver, guide->constraints[index]);
+      guide->constraints[index] = NULL;
+    }
+
+  if (index == MIN_WIDTH || index == NAT_WIDTH || index == MAX_WIDTH)
+    var = gtk_constraint_layout_get_attribute (guide->layout, GTK_CONSTRAINT_ATTRIBUTE_WIDTH, "guide", NULL, guide->bound_attributes);
+  else
+    var = gtk_constraint_layout_get_attribute (guide->layout, GTK_CONSTRAINT_ATTRIBUTE_HEIGHT, "guide", NULL, guide->bound_attributes);
+
+  /* We always install min-size constraints,
+   * but we avoid nat-size constraints if min == max
+   * and we avoid max-size constraints if max == G_MAXINT
+   */
+  if (index == MIN_WIDTH || index == MIN_HEIGHT)
+    {
+      guide->constraints[index] =
+        gtk_constraint_solver_add_constraint (solver,
+                                              var,
+                                              GTK_CONSTRAINT_RELATION_GE,
+                                              gtk_constraint_expression_new (guide->values[index]),
+                                              GTK_CONSTRAINT_STRENGTH_REQUIRED);
+    }
+  else if ((index == NAT_WIDTH && guide->values[MIN_WIDTH] != guide->values[MAX_WIDTH]) ||
+      (index == NAT_HEIGHT && guide->values[MIN_HEIGHT] != guide->values[MAX_HEIGHT]))
+    {
+      gtk_constraint_variable_set_value (var, guide->values[index]);
+      guide->constraints[index] =
+        gtk_constraint_solver_add_stay_variable (solver,
+                                                 var,
+                                                 guide->strength);
+    }
+  else if ((index == MAX_WIDTH || index == MAX_HEIGHT) &&
+           guide->values[index] < G_MAXINT)
+    {
+      guide->constraints[index] =
+        gtk_constraint_solver_add_constraint (solver,
+                                              var,
+                                              GTK_CONSTRAINT_RELATION_LE,
+                                              gtk_constraint_expression_new (guide->values[index]),
+                                              GTK_CONSTRAINT_STRENGTH_REQUIRED);
+    }
+
+  gtk_layout_manager_layout_changed (GTK_LAYOUT_MANAGER (guide->layout));
+}
+
+void
+gtk_constraint_guide_update (GtkConstraintGuide *guide)
+{
+  int i;
+
+  for (i = 0; i < LAST_VALUE; i++)
+    gtk_constraint_guide_update_constraint (guide, i);
+}
+
+void
+gtk_constraint_guide_detach (GtkConstraintGuide *guide)
+{
+  GtkConstraintSolver *solver;
+  int i;
+
+  if (!guide->layout)
+    return;
+
+  solver = gtk_constraint_layout_get_solver (guide->layout);
+  if (!solver)
+    return;
+
+  for (i = 0; i < LAST_VALUE; i++)
+    {
+      if (guide->constraints[i])
+        {
+          gtk_constraint_solver_remove_constraint (solver, guide->constraints[i]);
+          guide->constraints[i] = NULL;
+        }
+    }
+
+  g_hash_table_remove_all (guide->bound_attributes);
+}
+
+GtkConstraintVariable *
+gtk_constraint_guide_get_attribute (GtkConstraintGuide     *guide,
+                                    GtkConstraintAttribute  attr)
+{
+  GtkLayoutManager *manager = GTK_LAYOUT_MANAGER (guide->layout);
+  GtkWidget *widget = gtk_layout_manager_get_widget (manager);
+
+  return gtk_constraint_layout_get_attribute (guide->layout, attr, "guide", widget, guide->bound_attributes);
+}
+
+GtkConstraintLayout *
+gtk_constraint_guide_get_layout (GtkConstraintGuide *guide)
+{
+  return guide->layout;
+}
+
+void
+gtk_constraint_guide_set_layout (GtkConstraintGuide  *guide,
+                                 GtkConstraintLayout *layout)
+{
+  guide->layout = layout;
+}
+
+static void
+gtk_constraint_guide_set_property (GObject      *gobject,
+                                   guint         prop_id,
+                                   const GValue *value,
+                                   GParamSpec   *pspec)
+{
+  GtkConstraintGuide *self = GTK_CONSTRAINT_GUIDE (gobject);
+  int val;
+  GuideValue index;
+
+  switch (prop_id)
+    {
+    case PROP_MIN_WIDTH:
+    case PROP_MIN_HEIGHT:
+    case PROP_NAT_WIDTH:
+    case PROP_NAT_HEIGHT:
+    case PROP_MAX_WIDTH:
+    case PROP_MAX_HEIGHT:
+      val = g_value_get_int (value);
+      index = prop_id - 1;
+      if (self->values[index] != val)
+        {
+          self->values[index] = val;
+          g_object_notify_by_pspec (gobject, pspec);
+
+          gtk_constraint_guide_update_constraint (self, index);
+          if (index == MIN_WIDTH || index == MAX_WIDTH)
+            gtk_constraint_guide_update_constraint (self, NAT_WIDTH);
+          if (index == MIN_HEIGHT || index == MAX_HEIGHT)
+            gtk_constraint_guide_update_constraint (self, NAT_HEIGHT);
+        }
+      break;
+
+    case PROP_STRENGTH:
+      gtk_constraint_guide_set_strength (self, g_value_get_enum (value));
+      break;
+
+    case PROP_NAME:
+      gtk_constraint_guide_set_name (self, g_value_get_string (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_constraint_guide_get_property (GObject    *gobject,
+                                   guint       prop_id,
+                                   GValue     *value,
+                                   GParamSpec *pspec)
+{
+  GtkConstraintGuide *self = GTK_CONSTRAINT_GUIDE (gobject);
+
+  switch (prop_id)
+    {
+    case PROP_MIN_WIDTH:
+    case PROP_MIN_HEIGHT:
+    case PROP_NAT_WIDTH:
+    case PROP_NAT_HEIGHT:
+    case PROP_MAX_WIDTH:
+    case PROP_MAX_HEIGHT:
+      g_value_set_int (value, self->values[prop_id - 1]);
+      break;
+
+    case PROP_STRENGTH:
+      g_value_set_enum (value, self->strength);
+      break;
+
+    case PROP_NAME:
+      g_value_set_string (value, self->name);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_constraint_guide_finalize (GObject *object)
+{
+  GtkConstraintGuide *self = GTK_CONSTRAINT_GUIDE (object);
+
+  g_free (self->name);
+
+  g_clear_pointer (&self->bound_attributes, g_hash_table_unref);
+
+  G_OBJECT_CLASS (gtk_constraint_guide_parent_class)->finalize (object);
+}
+
+static void
+gtk_constraint_guide_class_init (GtkConstraintGuideClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+
+  object_class->finalize = gtk_constraint_guide_finalize;
+  object_class->set_property = gtk_constraint_guide_set_property;
+  object_class->get_property = gtk_constraint_guide_get_property;
+
+  /**
+   * GtkConstraintGuide:min-width:
+   *
+   * The minimum width of the guide.
+   */
+  guide_props[PROP_MIN_WIDTH] =
+      g_param_spec_int ("min-width",
+                        "Minimum width",
+                        "Minimum width",
+                        0, G_MAXINT, 0,
+                        G_PARAM_READWRITE|
+                        G_PARAM_EXPLICIT_NOTIFY);
+  /**
+   * GtkConstraintGuide:min-height:
+   *
+   * The minimum height of the guide.
+   */
+  guide_props[PROP_MIN_HEIGHT] =
+      g_param_spec_int ("min-height",
+                        "Minimum height",
+                        "Minimum height",
+                        0, G_MAXINT, 0,
+                        G_PARAM_READWRITE|
+                        G_PARAM_EXPLICIT_NOTIFY);
+  /**
+   * GtkConstraintGuide:nat-width:
+   *
+   * The preferred, or natural, width of the guide.
+   */
+  guide_props[PROP_NAT_WIDTH] =
+      g_param_spec_int ("nat-width",
+                        "Natural width",
+                        "Natural width",
+                        0, G_MAXINT, 0,
+                        G_PARAM_READWRITE|
+                        G_PARAM_EXPLICIT_NOTIFY);
+  /**
+   * GtkConstraintGuide:nat-height:
+   *
+   * The preferred, or natural, height of the guide.
+   */
+  guide_props[PROP_NAT_HEIGHT] =
+      g_param_spec_int ("nat-height",
+                        "Natural height",
+                        "Natural height",
+                        0, G_MAXINT, 0,
+                        G_PARAM_READWRITE|
+                        G_PARAM_EXPLICIT_NOTIFY);
+  /**
+   * GtkConstraintGuide:max-width:
+   *
+   * The maximum width of the guide.
+   */
+  guide_props[PROP_MAX_WIDTH] =
+      g_param_spec_int ("max-width",
+                        "Maximum width",
+                        "Maximum width",
+                        0, G_MAXINT, G_MAXINT,
+                        G_PARAM_READWRITE|
+                        G_PARAM_EXPLICIT_NOTIFY);
+  /**
+   * GtkConstraintGuide:max-height:
+   *
+   * The maximum height of the guide.
+   */
+  guide_props[PROP_MAX_HEIGHT] =
+      g_param_spec_int ("max-height",
+                        "Maximum height",
+                        "Maximum height",
+                        0, G_MAXINT, G_MAXINT,
+                        G_PARAM_READWRITE|
+                        G_PARAM_EXPLICIT_NOTIFY);
+  /**
+   * GtkConstraintGuide:strength:
+   *
+   * The #GtkConstraintStrength to be used for the constraint on
+   * the natural size of the guide.
+   */
+  guide_props[PROP_STRENGTH] =
+      g_param_spec_enum ("strength",
+                         "Strength",
+                         "The strength to use for natural size",
+                         GTK_TYPE_CONSTRAINT_STRENGTH,
+                         GTK_CONSTRAINT_STRENGTH_MEDIUM,
+                         G_PARAM_READWRITE|
+                         G_PARAM_EXPLICIT_NOTIFY);
+  /**
+   * GtkConstraintGuide:name:
+   *
+   * A name that identifies the #GtkConstraintGuide, for debugging.
+   */
+  guide_props[PROP_NAME] =
+      g_param_spec_string ("name",
+                           "Name",
+                           "A name to use in debug message",
+                           NULL,
+                           G_PARAM_READWRITE);
+
+  g_object_class_install_properties (object_class, LAST_PROP, guide_props);
+}
+
+/**
+ * gtk_constraint_guide_new:
+ *
+ * Creates a new #GtkConstraintGuide object.
+ *
+ * Return: a new #GtkConstraintGuide object.
+ */
+GtkConstraintGuide *
+gtk_constraint_guide_new (void)
+{
+  return g_object_new (GTK_TYPE_CONSTRAINT_GUIDE, NULL);
+}
+
+/**
+ * gtk_constraint_guide_set_min_size:
+ * @guide: a #GtkConstraintGuide object
+ * @width: the new minimum width, or -1 to not change it
+ * @height: the new minimum height, or -1 to not change it
+ *
+ * Sets the minimum size of @guide.
+ *
+ * If @guide is attached to a #GtkConstraintLayout,
+ * the constraints will be updated to reflect the new size.
+ */
+void
+gtk_constraint_guide_set_min_size (GtkConstraintGuide *guide,
+                                   int                 width,
+                                   int                 height)
+{
+  g_return_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide));
+  g_return_if_fail (width >= -1);
+  g_return_if_fail (height >= -1);
+
+  g_object_freeze_notify (G_OBJECT (guide));
+
+  if (width != -1)
+    g_object_set (guide, "min-width", width, NULL);
+
+  if (height != -1)
+    g_object_set (guide, "min-height", height, NULL);
+
+  g_object_thaw_notify (G_OBJECT (guide));
+}
+
+/**
+ * gtk_constraint_guide_get_min_size:
+ * @guide: a #GtkContraintGuide object
+ * @width: (allow-none): return location for the minimum width,
+ *     or %NULL
+ * @height: (allow-none): return location for the minimum height,
+ *     or %NULL
+ *
+ * Gets the minimum size of @guide.
+ */
+void
+gtk_constraint_guide_get_min_size (GtkConstraintGuide *guide,
+                                   int                *width,
+                                   int                *height)
+{
+  g_return_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide));
+
+  if (width)
+    *width = guide->values[MIN_WIDTH];
+  if (height)
+    *height = guide->values[MIN_HEIGHT];
+}
+
+/**
+ * gtk_constraint_guide_set_nat_size:
+ * @guide: a #GtkConstraintGuide object
+ * @width: the new natural width, or -1 to not change it
+ * @height: the new natural height, or -1 to not change it
+ *
+ * Sets the natural size of @guide.
+ *
+ * If @guide is attached to a #GtkConstraintLayout,
+ * the constraints will be updated to reflect the new size.
+ */
+void
+gtk_constraint_guide_set_nat_size (GtkConstraintGuide *guide,
+                                   int                 width,
+                                   int                 height)
+{
+  g_return_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide));
+  g_return_if_fail (width >= -1);
+  g_return_if_fail (height >= -1);
+
+  g_object_freeze_notify (G_OBJECT (guide));
+
+  if (width != -1)
+    g_object_set (guide, "nat-width", width, NULL);
+
+  if (height != -1)
+    g_object_set (guide, "nat-height", height, NULL);
+
+  g_object_thaw_notify (G_OBJECT (guide));
+}
+
+/**
+ * gtk_constraint_guide_get_nat_size:
+ * @guide: a #GtkContraintGuide object
+ * @width: (allow-none): return location for the natural width,
+ *     or %NULL
+ * @height: (allow-none): return location for the natural height,
+ *     or %NULL
+ *
+ * Gets the natural size of @guide.
+ */
+void
+gtk_constraint_guide_get_nat_size (GtkConstraintGuide *guide,
+                                   int                *width,
+                                   int                *height)
+{
+  g_return_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide));
+
+  if (width)
+    *width = guide->values[NAT_WIDTH];
+  if (height)
+    *height = guide->values[NAT_HEIGHT];
+}
+
+/**
+ * gtk_constraint_guide_set_max_size:
+ * @guide: a #GtkConstraintGuide object
+ * @width: the new maximum width, or -1 to not change it
+ * @height: the new maximum height, or -1 to not change it
+ *
+ * Sets the maximum size of @guide.
+ *
+ * If @guide is attached to a #GtkConstraintLayout,
+ * the constraints will be updated to reflect the new size.
+ */
+void
+gtk_constraint_guide_set_max_size (GtkConstraintGuide *guide,
+                                   int                 width,
+                                   int                 height)
+{
+  g_return_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide));
+  g_return_if_fail (width >= -1);
+  g_return_if_fail (height >= -1);
+
+  g_object_freeze_notify (G_OBJECT (guide));
+
+  if (width != -1)
+    g_object_set (guide, "max-width", width, NULL);
+
+  if (height != -1)
+    g_object_set (guide, "max-height", height, NULL);
+
+  g_object_thaw_notify (G_OBJECT (guide));
+}
+
+/**
+ * gtk_constraint_guide_get_max_size:
+ * @guide: a #GtkContraintGuide object
+ * @width: (allow-none): return location for the maximum width,
+ *     or %NULL
+ * @height: (allow-none): return location for the maximum height,
+ *     or %NULL
+ *
+ * Gets the maximum size of @guide.
+ */
+void
+gtk_constraint_guide_get_max_size (GtkConstraintGuide *guide,
+                                   int                *width,
+                                   int                *height)
+{
+  g_return_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide));
+
+  if (width)
+    *width = guide->values[MAX_WIDTH];
+  if (height)
+    *height = guide->values[MAX_HEIGHT];
+}
+
+/**
+ * gtk_constraint_guide_get_name:
+ * @guide: a #GtkConstraintGuide
+ *
+ * Retrieves the name set using gtk_constraint_guide_set_name().
+ *
+ * Returns: (transfer none) (nullable): the name of the guide
+ */
+const char *
+gtk_constraint_guide_get_name (GtkConstraintGuide *guide)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide), NULL);
+
+  return guide->name;
+}
+
+/**
+ * gtk_constraint_guide_set_name:
+ * @guide: a #GtkConstraintGuide
+ * @name: (nullable): a name for the @guide
+ *
+ * Sets a name for the given #GtkConstraintGuide.
+ *
+ * The name is useful for debugging purposes.
+ */
+void
+gtk_constraint_guide_set_name (GtkConstraintGuide *guide,
+                               const char         *name)
+{
+  g_return_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide));
+
+  g_free (guide->name);
+  guide->name = g_strdup (name);
+  g_object_notify_by_pspec (G_OBJECT (guide), guide_props[PROP_NAME]);
+}
+
+/**
+ * gtk_constraint_guide_get_strength:
+ * @guide: a #GtkConstraintGuide
+ *
+ * Retrieves the strength set using gtk_constraint_guide_set_strength().
+ *
+ * Returns: the strength of the constraint on the natural size
+ */
+GtkConstraintStrength
+gtk_constraint_guide_get_strength (GtkConstraintGuide *guide)
+{
+  g_return_val_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide),
+                        GTK_CONSTRAINT_STRENGTH_MEDIUM);
+
+  return guide->strength;
+}
+
+/**
+ * gtk_constraint_guide_set_strength:
+ * @guide: a #GtkConstraintGuide
+ * @strength: the strength of the constraint
+ *
+ * Sets the strength of the constraint on the natural size of the
+ * given #GtkConstraintGuide.
+ */
+void
+gtk_constraint_guide_set_strength (GtkConstraintGuide    *guide,
+                                   GtkConstraintStrength  strength)
+{
+  g_return_if_fail (GTK_IS_CONSTRAINT_GUIDE (guide));
+
+  if (guide->strength == strength)
+    return;
+
+  guide->strength = strength;
+  g_object_notify_by_pspec (G_OBJECT (guide), guide_props[PROP_STRENGTH]);
+  gtk_constraint_guide_update_constraint (guide, NAT_WIDTH);
+  gtk_constraint_guide_update_constraint (guide, NAT_HEIGHT);
+}
@@ -0,0 +1,83 @@
+/* gtkconstraintguide.h: Flexible space for constraints
+ * Copyright 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Matthias Clasen
+ */
+
+#pragma once
+
+#include <gtk/gtktypes.h>
+#include <gtk/gtkenums.h>
+#include <gtk/gtktypebuiltins.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_CONSTRAINT_GUIDE (gtk_constraint_guide_get_type ())
+
+/**
+ * GtkConstraintGuide:
+ *
+ * An object that can be added to a #GtkConstraintLayout and be
+ * used in constraints like a widget, without being drawn.
+ *
+ * Guides have a minimum, maximum and natural size. Depending
+ * on the constraints that are applied, they can act like a
+ * guideline that widgets can be aligned to, or like 'flexible space'.
+ */
+GDK_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (GtkConstraintGuide, gtk_constraint_guide, GTK, CONSTRAINT_GUIDE, GObject)
+
+GDK_AVAILABLE_IN_ALL
+GtkConstraintGuide *    gtk_constraint_guide_new                (void);
+
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_guide_set_min_size       (GtkConstraintGuide *guide,
+                                                                 int                 width,
+                                                                 int                 height);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_guide_get_min_size       (GtkConstraintGuide *guide,
+                                                                 int                *width,
+                                                                 int                *height);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_guide_set_nat_size       (GtkConstraintGuide *guide,
+                                                                 int                 width,
+                                                                 int                 height);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_guide_get_nat_size       (GtkConstraintGuide *guide,
+                                                                 int                *width,
+                                                                 int                *height);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_guide_set_max_size       (GtkConstraintGuide *guide,
+                                                                 int                 width,
+                                                                 int                 height);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_guide_get_max_size       (GtkConstraintGuide *guide,
+                                                                 int                *width,
+                                                                 int                *height);
+
+GDK_AVAILABLE_IN_ALL
+GtkConstraintStrength   gtk_constraint_guide_get_strength       (GtkConstraintGuide *guide);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_guide_set_strength       (GtkConstraintGuide    *guide,
+                                                                 GtkConstraintStrength  strength);
+
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_guide_set_name           (GtkConstraintGuide *guide,
+                                                                 const char         *name);
+GDK_AVAILABLE_IN_ALL
+const char *            gtk_constraint_guide_get_name           (GtkConstraintGuide *guide);
+
+G_END_DECLS
@@ -0,0 +1,38 @@
+/* gtkconstraintguideprivate.h: Constraint between two widgets
+ * Copyright 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Matthias Clasen
+ */
+
+#pragma once
+
+#include "gtkconstraintguide.h"
+#include "gtkconstraintlayout.h"
+#include "gtkconstrainttypesprivate.h"
+
+G_BEGIN_DECLS
+
+void                   gtk_constraint_guide_update        (GtkConstraintGuide     *guide);
+void                   gtk_constraint_guide_detach        (GtkConstraintGuide     *guide);
+
+GtkConstraintVariable *gtk_constraint_guide_get_attribute (GtkConstraintGuide      *guide,
+                                                           GtkConstraintAttribute  attr);
+
+GtkConstraintLayout   *gtk_constraint_guide_get_layout    (GtkConstraintGuide     *guide);
+void                   gtk_constraint_guide_set_layout    (GtkConstraintGuide     *guide,
+                                                           GtkConstraintLayout    *layout);
+
+G_END_DECLS
@@ -0,0 +1,93 @@
+/* gtkconstraintlayout.h: Layout manager using constraints
+ * Copyright 2019  GNOME Foundation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Emmanuele Bassi
+ */
+#pragma once
+
+#include <gtk/gtklayoutmanager.h>
+#include <gtk/gtkconstraint.h>
+#include <gtk/gtkconstraintguide.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_CONSTRAINT_LAYOUT (gtk_constraint_layout_get_type ())
+#define GTK_TYPE_CONSTRAINT_LAYOUT_CHILD (gtk_constraint_layout_child_get_type ())
+#define GTK_CONSTRAINT_VFL_PARSER_ERROR (gtk_constraint_vfl_parser_error_quark ())
+
+/**
+ * GtkConstraintLayoutChild:
+ *
+ * A #GtkLayoutChild in a #GtkConstraintLayout.
+ */
+GDK_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (GtkConstraintLayoutChild, gtk_constraint_layout_child, GTK, CONSTRAINT_LAYOUT_CHILD, GtkLayoutChild)
+
+/**
+ * GtkConstraintLayout:
+ *
+ * A layout manager using #GtkConstraint to describe
+ * relations between widgets.
+ */
+GDK_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (GtkConstraintLayout, gtk_constraint_layout, GTK, CONSTRAINT_LAYOUT, GtkLayoutManager)
+
+GDK_AVAILABLE_IN_ALL
+GQuark                  gtk_constraint_vfl_parser_error_quark   (void);
+
+GDK_AVAILABLE_IN_ALL
+GtkLayoutManager *      gtk_constraint_layout_new               (void);
+
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_layout_add_constraint    (GtkConstraintLayout *layout,
+                                                                 GtkConstraint       *constraint);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_layout_remove_constraint (GtkConstraintLayout *layout,
+                                                                 GtkConstraint       *constraint);
+
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_layout_add_guide         (GtkConstraintLayout *layout,
+                                                                 GtkConstraintGuide  *guide);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_layout_remove_guide      (GtkConstraintLayout *layout,
+                                                                 GtkConstraintGuide  *guide);
+GDK_AVAILABLE_IN_ALL
+void                    gtk_constraint_layout_remove_all_constraints            (GtkConstraintLayout *layout);
+
+GDK_AVAILABLE_IN_ALL
+GList *                 gtk_constraint_layout_add_constraints_from_description  (GtkConstraintLayout *layout,
+                                                                                 const char * const   lines[],
+                                                                                 gsize                n_lines,
+                                                                                 int                  hspacing,
+                                                                                 int                  vspacing,
+                                                                                 GError             **error,
+                                                                                 const char          *first_view,
+                                                                                 ...) G_GNUC_NULL_TERMINATED;
+GDK_AVAILABLE_IN_ALL
+GList *                 gtk_constraint_layout_add_constraints_from_descriptionv (GtkConstraintLayout *layout,
+                                                                                 const char * const   lines[],
+                                                                                 gsize                n_lines,
+                                                                                 int                  hspacing,
+                                                                                 int                  vspacing,
+                                                                                 GHashTable          *views,
+                                                                                 GError             **error);
+
+GDK_AVAILABLE_IN_ALL
+GListModel *          gtk_constraint_layout_observe_constraints (GtkConstraintLayout *layout);
+GDK_AVAILABLE_IN_ALL
+GListModel *          gtk_constraint_layout_observe_guides (GtkConstraintLayout *layout);
+
+G_END_DECLS
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Matthias Clasen
+ */
+
+#pragma once
+
+#include "gtkconstraintlayout.h"
+#include "gtkconstraintsolverprivate.h"
+
+G_BEGIN_DECLS
+
+GtkConstraintSolver *
+gtk_constraint_layout_get_solver (GtkConstraintLayout *layout);
+
+GtkConstraintVariable *
+gtk_constraint_layout_get_attribute (GtkConstraintLayout    *layout,
+                                     GtkConstraintAttribute  attr,
+                                     const char             *prefix,
+                                     GtkWidget              *widget,
+                                     GHashTable             *bound_attributes);
+
+G_END_DECLS
@@ -0,0 +1,60 @@
+/* gtkconstraintprivate.h: Constraint between two widgets
+ * Copyright 2019  GNOME Foundation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Emmanuele Bassi
+ */
+
+#pragma once
+
+#include "gtkconstraint.h"
+#include "gtkconstrainttypesprivate.h"
+
+G_BEGIN_DECLS
+
+struct _GtkConstraint
+{
+  GObject parent_instance;
+
+  GtkConstraintAttribute target_attribute;
+  GtkConstraintAttribute source_attribute;
+
+  GtkConstraintTarget *target;
+  GtkConstraintTarget *source;
+
+  GtkConstraintRelation relation;
+
+  double multiplier;
+  double constant;
+
+  int strength;
+
+  /* A reference to the real constraint inside the
+   * GtkConstraintSolver, so we can remove it when
+   * finalizing the GtkConstraint instance
+   */
+  GtkConstraintRef *constraint_ref;
+
+  GtkConstraintSolver *solver;
+
+  guint active : 1;
+};
+
+void    gtk_constraint_attach           (GtkConstraint       *constraint,
+                                         GtkConstraintSolver *solver,
+                                         GtkConstraintRef    *ref);
+void    gtk_constraint_detach           (GtkConstraint       *constraint);
+
+G_END_DECLS
@@ -0,0 +1,117 @@
+/* gtkconstraintsolverprivate.h: Constraint solver based on the Cassowary method
+ * Copyright 2019  GNOME Foundation
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Emmanuele Bassi
+ */
+
+#pragma once
+
+#include "gtkconstrainttypesprivate.h"
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_CONSTRAINT_SOLVER (gtk_constraint_solver_get_type())
+
+G_DECLARE_FINAL_TYPE (GtkConstraintSolver, gtk_constraint_solver, GTK, CONSTRAINT_SOLVER, GObject)
+
+GtkConstraintSolver *
+gtk_constraint_solver_new (void);
+
+void
+gtk_constraint_solver_freeze (GtkConstraintSolver *solver);
+
+void
+gtk_constraint_solver_thaw (GtkConstraintSolver *solver);
+
+void
+gtk_constraint_solver_resolve (GtkConstraintSolver *solver);
+
+GtkConstraintVariable *
+gtk_constraint_solver_create_variable (GtkConstraintSolver *solver,
+                                       const char          *prefix,
+                                       const char          *name,
+                                       double               value);
+
+GtkConstraintRef *
+gtk_constraint_solver_add_constraint (GtkConstraintSolver     *solver,
+                                      GtkConstraintVariable   *variable,
+                                      GtkConstraintRelation    relation,
+                                      GtkConstraintExpression *expression,
+                                      int                      strength);
+
+void
+gtk_constraint_solver_remove_constraint (GtkConstraintSolver *solver,
+                                         GtkConstraintRef    *reference);
+
+GtkConstraintRef *
+gtk_constraint_solver_add_stay_variable (GtkConstraintSolver   *solver,
+                                         GtkConstraintVariable *variable,
+                                         int                    strength);
+
+void
+gtk_constraint_solver_remove_stay_variable (GtkConstraintSolver   *solver,
+                                            GtkConstraintVariable *variable);
+
+gboolean
+gtk_constraint_solver_has_stay_variable (GtkConstraintSolver   *solver,
+                                         GtkConstraintVariable *variable);
+
+GtkConstraintRef *
+gtk_constraint_solver_add_edit_variable (GtkConstraintSolver   *solver,
+                                         GtkConstraintVariable *variable,
+                                         int                    strength);
+
+void
+gtk_constraint_solver_remove_edit_variable (GtkConstraintSolver   *solver,
+                                            GtkConstraintVariable *variable);
+
+gboolean
+gtk_constraint_solver_has_edit_variable (GtkConstraintSolver   *solver,
+                                         GtkConstraintVariable *variable);
+
+void
+gtk_constraint_solver_suggest_value (GtkConstraintSolver   *solver,
+                                     GtkConstraintVariable *variable,
+                                     double                 value);
+
+void
+gtk_constraint_solver_begin_edit (GtkConstraintSolver *solver);
+
+void
+gtk_constraint_solver_end_edit (GtkConstraintSolver *solver);
+
+void
+gtk_constraint_solver_note_added_variable (GtkConstraintSolver *self,
+                                           GtkConstraintVariable *variable,
+                                           GtkConstraintVariable *subject);
+
+void
+gtk_constraint_solver_note_removed_variable (GtkConstraintSolver *self,
+                                             GtkConstraintVariable *variable,
+                                             GtkConstraintVariable *subject);
+
+void
+gtk_constraint_solver_clear (GtkConstraintSolver *solver);
+
+char *
+gtk_constraint_solver_to_string (GtkConstraintSolver *solver);
+
+char *
+gtk_constraint_solver_statistics (GtkConstraintSolver *solver);
+
+G_END_DECLS
@@ -0,0 +1,50 @@
+/* gtkconstrainttypesprivate.h: Private types for the constraint solver
+ * Copyright 2019  GNOME Foundation
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Emmanuele Bassi
+ */
+
+#pragma once
+
+#include <gtk/gtktypes.h>
+#include <gtk/gtkenums.h>
+
+G_BEGIN_DECLS
+
+typedef struct _GtkConstraintVariable           GtkConstraintVariable;
+typedef struct _GtkConstraintExpression         GtkConstraintExpression;
+typedef struct _GtkConstraintExpressionBuilder  GtkConstraintExpressionBuilder;
+
+/*< private >
+ * GtkConstraintRef:
+ *
+ * A reference to a constraint stored inside the solver; while #GtkConstraint
+ * represent the public API, a #GtkConstraintRef represents data stored inside
+ * the solver. A #GtkConstraintRef is completely opaque, and should only be
+ * used to remove a constraint from the solver.
+ */
+typedef struct _GtkConstraintRef                GtkConstraintRef;
+
+/*< private >
+ * GtkConstraintSolver:
+ *
+ * A simplex solver using the Cassowary constraint solving algorithm.
+ */
+typedef struct _GtkConstraintSolver             GtkConstraintSolver;
+
+G_END_DECLS
@@ -0,0 +1,76 @@
+/* gtkconstraintvflparserprivate.h: VFL constraint definition parser 
+ *
+ * Copyright 2017  Endless
+ * Copyright 2019  GNOME Foundation
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "gtkconstrainttypesprivate.h"
+
+G_BEGIN_DECLS
+
+typedef struct _GtkConstraintVflParser       GtkConstraintVflParser;
+
+typedef struct {
+  const char *view1;
+  const char *attr1;
+  GtkConstraintRelation relation;
+  const char *view2;
+  const char *attr2;
+  double constant;
+  double multiplier;
+  double strength;
+} GtkConstraintVfl;
+
+GtkConstraintVflParser *
+gtk_constraint_vfl_parser_new (void);
+
+void
+gtk_constraint_vfl_parser_free (GtkConstraintVflParser *parser);
+
+void
+gtk_constraint_vfl_parser_set_default_spacing (GtkConstraintVflParser *parser,
+                                               int hspacing,
+                                               int vspacing);
+
+void
+gtk_constraint_vfl_parser_set_metrics (GtkConstraintVflParser *parser,
+                                       GHashTable *metrics);
+
+void
+gtk_constraint_vfl_parser_set_views (GtkConstraintVflParser *parser,
+                                     GHashTable *views);
+
+gboolean
+gtk_constraint_vfl_parser_parse_line (GtkConstraintVflParser *parser,
+                                      const char *line,
+                                      gssize len,
+                                      GError **error);
+
+int
+gtk_constraint_vfl_parser_get_error_offset (GtkConstraintVflParser *parser);
+
+int
+gtk_constraint_vfl_parser_get_error_range (GtkConstraintVflParser *parser);
+
+GtkConstraintVfl *
+gtk_constraint_vfl_parser_get_constraints (GtkConstraintVflParser *parser,
+                                           int *n_constraints);
+
+G_END_DECLS
@@ -51,7 +51,8 @@ typedef enum {
  GTK_DEBUG_ACTIONS         = 1 << 13,
  GTK_DEBUG_RESIZE          = 1 << 14,
  GTK_DEBUG_LAYOUT          = 1 << 15,
-  GTK_DEBUG_SNAPSHOT        = 1 << 16
+  GTK_DEBUG_SNAPSHOT        = 1 << 16,
+  GTK_DEBUG_CONSTRAINTS     = 1 << 17,
 } GtkDebugFlag;

 #ifdef G_ENABLE_DEBUG
@@ -1053,4 +1053,98 @@ typedef enum {
  GTK_PICK_NON_TARGETABLE = 1 << 1
 } GtkPickFlags;

+/**
+ * GtkConstraintRelation:
+ * @GTK_CONSTRAINT_RELATION_EQ: Equal
+ * @GTK_CONSTRAINT_RELATION_LE: Less than, or equal
+ * @GTK_CONSTRAINT_RELATION_GE: Greater than, or equal
+ *
+ * The relation between two terms of a constraint.
+ */
+typedef enum {
+  GTK_CONSTRAINT_RELATION_LE = -1,
+  GTK_CONSTRAINT_RELATION_EQ = 0,
+  GTK_CONSTRAINT_RELATION_GE = 1
+} GtkConstraintRelation;
+
+/**
+ * GtkConstraintStrength:
+ * @GTK_CONSTRAINT_STRENGTH_REQUIRED: The constraint is required towards solving the layout
+ * @GTK_CONSTRAINT_STRENGTH_STRONG: A strong constraint
+ * @GTK_CONSTRAINT_STRENGTH_MEDIUM: A medium constraint
+ * @GTK_CONSTRAINT_STRENGTH_WEAK: A weak constraint
+ *
+ * The strength of a constraint, expressed as a symbolic constant.
+ *
+ * The strength of a #GtkConstraint can be expressed with any positive
+ * integer; the values of this enumeration can be used for readability.
+ */
+typedef enum {
+  GTK_CONSTRAINT_STRENGTH_REQUIRED = 1001001000,
+  GTK_CONSTRAINT_STRENGTH_STRONG   = 1000000000,
+  GTK_CONSTRAINT_STRENGTH_MEDIUM   = 1000,
+  GTK_CONSTRAINT_STRENGTH_WEAK     = 1
+} GtkConstraintStrength;
+
+/**
+ * GtkConstraintAttribute:
+ * @GTK_CONSTRAINT_ATTRIBUTE_NONE: No attribute, used for constant
+ *   relations
+ * @GTK_CONSTRAINT_ATTRIBUTE_LEFT: The left edge of a widget, regardless of
+ *   text direction
+ * @GTK_CONSTRAINT_ATTRIBUTE_RIGHT: The right edge of a widget, regardless
+ *   of text direction
+ * @GTK_CONSTRAINT_ATTRIBUTE_TOP: The top edge of a widget
+ * @GTK_CONSTRAINT_ATTRIBUTE_BOTTOM: The bottom edge of a widget
+ * @GTK_CONSTRAINT_ATTRIBUTE_START: The leading edge of a widget, depending
+ *   on text direction; equivalent to %GTK_CONSTRAINT_ATTRIBUTE_LEFT for LTR
+ *   languages, and %GTK_CONSTRAINT_ATTRIBUTE_RIGHT for RTL ones
+ * @GTK_CONSTRAINT_ATTRIBUTE_END: The trailing edge of a widget, depending
+ *   on text direction; equivalent to %GTK_CONSTRAINT_ATTRIBUTE_RIGHT for LTR
+ *   languages, and %GTK_CONSTRAINT_ATTRIBUTE_LEFT for RTL ones
+ * @GTK_CONSTRAINT_ATTRIBUTE_WIDTH: The width of a widget
+ * @GTK_CONSTRAINT_ATTRIBUTE_HEIGHT: The height of a widget
+ * @GTK_CONSTRAINT_ATTRIBUTE_CENTER_X: The center of a widget, on the
+ *   horizontal axis
+ * @GTK_CONSTRAINT_ATTRIBUTE_CENTER_Y: The center of a widget, on the
+ *   vertical axis
+ * @GTK_CONSTRAINT_ATTRIBUTE_BASELINE: The baseline of a widget
+ *
+ * The widget attributes that can be used when creating a #GtkConstraint.
+ */
+typedef enum {
+  GTK_CONSTRAINT_ATTRIBUTE_NONE,
+  GTK_CONSTRAINT_ATTRIBUTE_LEFT,
+  GTK_CONSTRAINT_ATTRIBUTE_RIGHT,
+  GTK_CONSTRAINT_ATTRIBUTE_TOP,
+  GTK_CONSTRAINT_ATTRIBUTE_BOTTOM,
+  GTK_CONSTRAINT_ATTRIBUTE_START,
+  GTK_CONSTRAINT_ATTRIBUTE_END,
+  GTK_CONSTRAINT_ATTRIBUTE_WIDTH,
+  GTK_CONSTRAINT_ATTRIBUTE_HEIGHT,
+  GTK_CONSTRAINT_ATTRIBUTE_CENTER_X,
+  GTK_CONSTRAINT_ATTRIBUTE_CENTER_Y,
+  GTK_CONSTRAINT_ATTRIBUTE_BASELINE
+} GtkConstraintAttribute;
+
+/**
+ * GtkConstraintVflParserError:
+ * @GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_SYMBOL: Invalid or unknown symbol
+ * @GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_ATTRIBUTE: Invalid or unknown attribute
+ * @GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_VIEW: Invalid or unknown view
+ * @GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_METRIC: Invalid or unknown metric
+ * @GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_PRIORITY: Invalid or unknown priority
+ * @GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_RELATION: Invalid or unknown relation
+ *
+ * Domain for VFL parsing errors.
+ */
+typedef enum {
+  GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_SYMBOL,
+  GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_ATTRIBUTE,
+  GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_VIEW,
+  GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_METRIC,
+  GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_PRIORITY,
+  GTK_CONSTRAINT_VFL_PARSER_ERROR_INVALID_RELATION
+} GtkConstraintVflParserError;
+
 #endif /* __GTK_ENUMS_H__ */
@@ -216,17 +216,25 @@ gtk_flatten_list_model_items_changed_cb (GListModel          *model,
                                         guint                added,
                                         gpointer             _node)
 {
-  FlattenNode *node = _node, *parent;
+  FlattenNode *node = _node, *parent, *left;
  GtkFlattenListModel *self = node->list;
  guint real_position;

  gtk_rb_tree_node_mark_dirty (node);
+  real_position = position;

-  for (real_position = position;
+  left = gtk_rb_tree_node_get_left (node);
+  if (left)
+    {
+      FlattenAugment *aug = gtk_rb_tree_get_augment (self->items, left);
+      real_position += aug->n_items;
+    }
+
+  for (;
       (parent = gtk_rb_tree_node_get_parent (node)) != NULL;
       node = parent)
    {
-      FlattenNode *left = gtk_rb_tree_node_get_left (parent);
+      left = gtk_rb_tree_node_get_left (parent);
      if (left != node)
        {
          if (left)
@@ -212,6 +212,8 @@ gtk_grid_layout_child_class_init (GtkGridLayoutChildClass *klass)
 static void
 gtk_grid_layout_child_init (GtkGridLayoutChild *self)
 {
+  CHILD_ROW_SPAN (self) = 1;
+  CHILD_COL_SPAN (self) = 1;
 }

 /**
@@ -91,6 +91,7 @@

 typedef struct {
  GtkWidget *widget;
+  GtkRoot *root;

  /* HashTable<Widget, LayoutChild> */
  GHashTable *layout_children;
@@ -98,6 +99,16 @@ typedef struct {

 G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (GtkLayoutManager, gtk_layout_manager, G_TYPE_OBJECT)

+static void
+gtk_layout_manager_real_root (GtkLayoutManager *manager)
+{
+}
+
+static void
+gtk_layout_manager_real_unroot (GtkLayoutManager *manager)
+{
+}
+
 static GtkSizeRequestMode
 gtk_layout_manager_real_get_request_mode (GtkLayoutManager *manager,
                                          GtkWidget        *widget)
@@ -188,13 +199,30 @@ gtk_layout_manager_real_create_layout_child (GtkLayoutManager *manager,
                       NULL);
 }

+static void
+gtk_layout_manager_finalize (GObject *gobject)
+{
+  GtkLayoutManager *self = GTK_LAYOUT_MANAGER (gobject);
+  GtkLayoutManagerPrivate *priv = gtk_layout_manager_get_instance_private (self);
+
+  g_clear_pointer (&priv->layout_children, g_hash_table_unref);
+
+  G_OBJECT_CLASS (gtk_layout_manager_parent_class)->finalize (gobject);
+}
+
 static void
 gtk_layout_manager_class_init (GtkLayoutManagerClass *klass)
 {
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  gobject_class->finalize = gtk_layout_manager_finalize;
+
  klass->get_request_mode = gtk_layout_manager_real_get_request_mode;
  klass->measure = gtk_layout_manager_real_measure;
  klass->allocate = gtk_layout_manager_real_allocate;
  klass->create_layout_child = gtk_layout_manager_real_create_layout_child;
+  klass->root = gtk_layout_manager_real_root;
+  klass->unroot = gtk_layout_manager_real_unroot;
 }

 static void
@@ -226,6 +254,38 @@ gtk_layout_manager_set_widget (GtkLayoutManager *layout_manager,
    }

  priv->widget = widget;
+
+  if (widget != NULL)
+    gtk_layout_manager_set_root (layout_manager, gtk_widget_get_root (widget));
+}
+
+/*< private >
+ * gtk_layout_manager_set_root:
+ * @layout_manager: a #GtkLayoutManager
+ * @root: (nullable): a #GtkWidget implementing #GtkRoot
+ *
+ * Sets a back pointer from @root to @layout_manager.
+ *
+ * This function is called by #GtkWidget when getting rooted and unrooted,
+ * and will call #GtkLayoutManagerClass.root() or #GtkLayoutManagerClass.unroot()
+ * depending on whether @root is a #GtkWidget or %NULL.
+ */
+void
+gtk_layout_manager_set_root (GtkLayoutManager *layout_manager,
+                             GtkRoot          *root)
+{
+  GtkLayoutManagerPrivate *priv = gtk_layout_manager_get_instance_private (layout_manager);
+  GtkRoot *old_root = priv->root;
+
+  priv->root = root;
+
+  if (old_root != root)
+    {
+      if (priv->root != NULL)
+        GTK_LAYOUT_MANAGER_GET_CLASS (layout_manager)->root (layout_manager);
+      else
+        GTK_LAYOUT_MANAGER_GET_CLASS (layout_manager)->unroot (layout_manager);
+    }
 }

 /**
@@ -42,6 +42,10 @@ G_DECLARE_DERIVABLE_TYPE (GtkLayoutManager, gtk_layout_manager, GTK, LAYOUT_MANA
 * @layout_child_type: the type of #GtkLayoutChild used by this layout manager
 * @create_layout_child: a virtual function, used to create a #GtkLayoutChild
 *   meta object for the layout properties
+ * @root: a virtual function, called when the widget using the layout
+ *   manager is attached to a #GtkRoot
+ * @unroot: a virtual function, called when the widget using the layout
+ *   manager is detached from a #GtkRoot
 *
 * The `GtkLayoutManagerClass` structure contains only private data, and
 * should only be accessed through the provided API, or when subclassing
@@ -77,6 +81,9 @@ struct _GtkLayoutManagerClass
                                              GtkWidget        *widget,
                                              GtkWidget        *for_child);

+  void               (* root)                (GtkLayoutManager *manager);
+  void               (* unroot)              (GtkLayoutManager *manager);
+
  /*< private >*/
  gpointer _padding[16];
 };
@@ -10,4 +10,7 @@ void gtk_layout_manager_set_widget (GtkLayoutManager *manager,
 void gtk_layout_manager_remove_layout_child (GtkLayoutManager *manager,
                                             GtkWidget        *widget);

+void gtk_layout_manager_set_root (GtkLayoutManager *manager,
+                                  GtkRoot          *root);
+
 G_END_DECLS
@@ -179,7 +179,8 @@ static const GDebugKey gtk_debug_keys[] = {
  { "actions", GTK_DEBUG_ACTIONS },
  { "resize", GTK_DEBUG_RESIZE },
  { "layout", GTK_DEBUG_LAYOUT },
-  { "snapshot", GTK_DEBUG_SNAPSHOT }
+  { "snapshot", GTK_DEBUG_SNAPSHOT },
+  { "constraints", GTK_DEBUG_CONSTRAINTS },
 };
 #endif /* G_ENABLE_DEBUG */

@@ -50,10 +50,18 @@ gtk_root_default_get_display (GtkRoot *self)
  return gdk_display_get_default ();
 }

+
+static GtkConstraintSolver *
+gtk_root_default_get_constraint_solver (GtkRoot *self)
+{
+  return NULL;
+}
+
 static void
 gtk_root_default_init (GtkRootInterface *iface)
 {
  iface->get_display = gtk_root_default_get_display;
+  iface->get_constraint_solver = gtk_root_default_get_constraint_solver;

  g_object_interface_install_property (iface,
      g_param_spec_object ("focus-widget",
@@ -82,6 +90,17 @@ gtk_root_get_display (GtkRoot *self)
  return iface->get_display (self);
 }

+GtkConstraintSolver *
+gtk_root_get_constraint_solver (GtkRoot *self)
+{
+  GtkRootInterface *iface;
+
+  g_return_val_if_fail (GTK_IS_ROOT (self), NULL);
+
+  iface = GTK_ROOT_GET_IFACE (self);
+  return iface->get_constraint_solver (self);
+}
+
 /**
 * gtk_root_set_focus:
 * @self: a #GtkRoot
@@ -34,20 +34,6 @@ G_BEGIN_DECLS
 GDK_AVAILABLE_IN_ALL
 G_DECLARE_INTERFACE (GtkRoot, gtk_root, GTK, ROOT, GtkWidget)

-/**
- * GtkRootIface:
- *
- * The list of functions that must be implemented for the #GtkRoot interface.
- */
-struct _GtkRootInterface
-{
-  /*< private >*/
-  GTypeInterface g_iface;
-
-  /*< public >*/
-  GdkDisplay * (* get_display)  (GtkRoot *self);
-};
-
 GDK_AVAILABLE_IN_ALL
 GdkDisplay * gtk_root_get_display (GtkRoot *self);

@@ -3,8 +3,28 @@

 #include "gtkroot.h"

+#include "gtkconstraintsolverprivate.h"
+
 G_BEGIN_DECLS

+/**
+ * GtkRootIface:
+ *
+ * The list of functions that must be implemented for the #GtkRoot interface.
+ */
+struct _GtkRootInterface
+{
+  /*< private >*/
+  GTypeInterface g_iface;
+
+  /*< public >*/
+  GdkDisplay * (* get_display)  (GtkRoot *self);
+
+  GtkConstraintSolver * (* get_constraint_solver) (GtkRoot *self);
+};
+
+GtkConstraintSolver *   gtk_root_get_constraint_solver  (GtkRoot *self);
+
 enum {
  GTK_ROOT_PROP_FOCUS_WIDGET,
  GTK_ROOT_NUM_PROPERTIES
@@ -73,6 +73,7 @@
 #include "gtkwindowgroup.h"
 #include "gtkwindowprivate.h"
 #include "gtknativeprivate.h"
+#include "gtkconstraint.h"

 #include "a11y/gtkwidgetaccessible.h"
 #include "inspector/window.h"
@@ -770,6 +771,13 @@ gtk_widget_get_type (void)
 	NULL /* interface data */
      };

+      const GInterfaceInfo constraint_target_info =
+      {
+	(GInterfaceInitFunc) NULL,
+	(GInterfaceFinalizeFunc) NULL,
+	NULL /* interface data */
+      };
+
      widget_type = g_type_register_static (G_TYPE_INITIALLY_UNOWNED, g_intern_static_string ("GtkWidget"),
                                            &widget_info, G_TYPE_FLAG_ABSTRACT);

@@ -782,6 +790,8 @@ gtk_widget_get_type (void)
                                   &accessibility_info) ;
      g_type_add_interface_static (widget_type, GTK_TYPE_BUILDABLE,
                                   &buildable_info) ;
+      g_type_add_interface_static (widget_type, GTK_TYPE_CONSTRAINT_TARGET,
+                                   &constraint_target_info) ;
    }

  return widget_type;
@@ -2893,6 +2903,9 @@ gtk_widget_root (GtkWidget *widget)

  _gtk_widget_update_parent_muxer (widget);

+  if (priv->layout_manager)
+    gtk_layout_manager_set_root (priv->layout_manager, priv->root);
+
  GTK_WIDGET_GET_CLASS (widget)->root (widget);

  if (!GTK_IS_ROOT (widget))
@@ -2920,6 +2933,9 @@ gtk_widget_unroot (GtkWidget *widget)
  if (priv->context)
    gtk_style_context_set_display (priv->context, gdk_display_get_default ());

+  if (priv->layout_manager)
+    gtk_layout_manager_set_root (priv->layout_manager, NULL);
+
  if (g_object_get_qdata (G_OBJECT (widget), quark_pango_context))
    g_object_set_qdata (G_OBJECT (widget), quark_pango_context, NULL);

@@ -281,6 +281,8 @@ typedef struct
  GskRenderer *renderer;

  GList *foci;
+
+  GtkConstraintSolver *constraint_solver;
 } GtkWindowPrivate;

 #ifdef GDK_WINDOWING_X11
@@ -1883,6 +1885,9 @@ gtk_window_init (GtkWindow *window)
  g_signal_connect_swapped (priv->key_controller, "key-released",
                            G_CALLBACK (gtk_window_key_released), window);
  gtk_widget_add_controller (widget, priv->key_controller);
+
+  /* Shared constraint solver */
+  priv->constraint_solver = gtk_constraint_solver_new ();
 }

 static GtkGesture *
@@ -2353,6 +2358,15 @@ gtk_window_native_get_renderer (GtkNative *native)
  return priv->renderer;
 }

+static GtkConstraintSolver *
+gtk_window_root_get_constraint_solver (GtkRoot *root)
+{
+  GtkWindow *self = GTK_WINDOW (root);
+  GtkWindowPrivate *priv = gtk_window_get_instance_private (self);
+
+  return priv->constraint_solver;
+}
+
 static void
 gtk_window_native_get_surface_transform (GtkNative *native,
                                         int       *x,
@@ -2381,6 +2395,7 @@ static void
 gtk_window_root_interface_init (GtkRootInterface *iface)
 {
  iface->get_display = gtk_window_root_get_display;
+  iface->get_constraint_solver = gtk_window_root_get_constraint_solver;
 }

 static void
@@ -4723,6 +4738,7 @@ gtk_window_finalize (GObject *object)
      priv->mnemonics_display_timeout_id = 0;
    }

+  g_clear_object (&priv->constraint_solver);
  g_clear_object (&priv->renderer);

  G_OBJECT_CLASS (gtk_window_parent_class)->finalize (object);
@@ -37,6 +37,9 @@ gtk_private_sources = files([
  'gtkcolorpickershell.c',
  'gtkcolorscale.c',
  'gtkcolorswatch.c',
+  'gtkconstraintexpression.c',
+  'gtkconstraintsolver.c',
+  'gtkconstraintvflparser.c',
  'gtkcssanimatedstyle.c',
  'gtkcssanimation.c',
  'gtkcssarrayvalue.c',
@@ -200,6 +203,9 @@ gtk_public_sources = files([
  'gtkcombobox.c',
  'gtkcomboboxtext.c',
  'gtkcomposetable.c',
+  'gtkconstraintguide.c',
+  'gtkconstraintlayout.c',
+  'gtkconstraint.c',
  'gtkcontainer.c',
  'gtkcssprovider.c',
  'gtkdialog.c',
@@ -459,6 +465,9 @@ gtk_public_headers = files([
  'gtkcolorutils.h',
  'gtkcombobox.h',
  'gtkcomboboxtext.h',
+  'gtkconstraintguide.h',
+  'gtkconstraintlayout.h',
+  'gtkconstraint.h',
  'gtkcontainer.h',
  'gtkcssprovider.h',
  'gtkcustomlayout.h',
@@ -2178,11 +2178,11 @@ popover>contents {
  margin: 0px;
 }

-popover>contents.background {
+popover.background>contents {

  background-color: $popover_bg_color;
  box-shadow: 0 1px 2px transparentize(black, 0.7);
-  .csd &, & { 
+  .csd &, & {
    border: 1px solid $borders_color;
    border-radius: $popover_radius;
  }
@@ -4766,8 +4766,9 @@ popover.menu {
    padding-bottom: 5px;
  }

+  arrow,
  &.background contents {
-    background: white;
+    background-color: $menu_color;
  }

  &.background separator {
@@ -82,9 +82,9 @@ assistant .sidebar label { padding: 6px 12px; }

 assistant .sidebar label.highlight { background-color: #5a5a59; }

-.csd popover > contents.background.touch-selection, .csd popover > contents.background.magnifier, popover > contents.background.touch-selection, popover > contents.background.magnifier, .csd popover > contents.background.osd, popover > contents.background.osd, .app-notification, .app-notification.frame, .osd .scale-popup, .osd { color: #eeeeec; border: none; background-color: rgba(38, 38, 38, 0.7); background-clip: padding-box; text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; }
+.csd popover.background > contents.touch-selection, .csd popover.background > contents.magnifier, popover.background > contents.touch-selection, popover.background > contents.magnifier, .csd popover.background > contents.osd, popover.background > contents.osd, .app-notification, .app-notification.frame, .osd .scale-popup, .osd { color: #eeeeec; border: none; background-color: rgba(37, 37, 38, 0.7); background-clip: padding-box; text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; }

-.csd popover > contents.background.touch-selection:backdrop, .csd popover > contents.background.magnifier:backdrop, popover > contents.background.touch-selection:backdrop, popover > contents.background.magnifier:backdrop, .csd popover > contents.background.osd:backdrop, popover > contents.background.osd:backdrop, .app-notification:backdrop, .osd .scale-popup:backdrop, .osd:backdrop { text-shadow: none; -gtk-icon-shadow: none; }
+.csd popover.background > contents.touch-selection:backdrop, .csd popover.background > contents.magnifier:backdrop, popover.background > contents.touch-selection:backdrop, popover.background > contents.magnifier:backdrop, .csd popover.background > contents.osd:backdrop, popover.background > contents.osd:backdrop, .app-notification:backdrop, .osd .scale-popup:backdrop, .osd:backdrop { text-shadow: none; -gtk-icon-shadow: none; }

 /********************* Spinner Animation * */
@keyframes spin { to { -gtk-icon-transform: rotate(1turn); } }
@@ -265,7 +265,7 @@ row:selected button.sidebar-button:not(:active):not(:checked):not(:hover):not(di

 row:selected button.sidebar-button:not(:active):not(:checked):not(:hover):not(disabled):backdrop, row:selected button.flat:not(:active):not(:checked):not(:hover):not(disabled):backdrop { color: #919190; }

-button.osd { min-width: 26px; min-height: 32px; color: #eeeeec; border-radius: 5px; color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); border: none; box-shadow: none; }
+button.osd { min-width: 26px; min-height: 32px; color: #eeeeec; border-radius: 5px; color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); border: none; box-shadow: none; }

 button.osd.image-button { min-width: 34px; }

@@ -275,27 +275,27 @@ button.osd:active, button.osd:checked { color: white; border-color: rgba(0, 0, 0

 button.osd:disabled:backdrop, button.osd:disabled { color: #8a8a89; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(58, 58, 57, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; border: none; }

-button.osd:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; border: none; }
+button.osd:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; border: none; }

-.csd popover > contents.background.touch-selection button, .csd popover > contents.background.magnifier button, popover > contents.background.touch-selection button, popover > contents.background.magnifier button, .app-notification button, .app-notification.frame button, .osd button { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }
+.csd popover.background > contents.touch-selection button, .csd popover.background > contents.magnifier button, popover.background > contents.touch-selection button, popover.background > contents.magnifier button, .app-notification button, .app-notification.frame button, .osd button { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }

-.csd popover > contents.background.touch-selection button:hover, .csd popover > contents.background.magnifier button:hover, popover > contents.background.touch-selection button:hover, popover > contents.background.magnifier button:hover, .app-notification button:hover, .osd button:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(68, 68, 68, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }
+.csd popover.background > contents.touch-selection button:hover, .csd popover.background > contents.magnifier button:hover, popover.background > contents.touch-selection button:hover, popover.background > contents.magnifier button:hover, .app-notification button:hover, .osd button:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(68, 68, 68, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }

-.csd popover > contents.background.touch-selection button:active:backdrop, .csd popover > contents.background.magnifier button:active:backdrop, popover > contents.background.touch-selection button:active:backdrop, popover > contents.background.magnifier button:active:backdrop, .app-notification button:active:backdrop, .csd popover > contents.background.touch-selection button:active, .csd popover > contents.background.magnifier button:active, popover > contents.background.touch-selection button:active, popover > contents.background.magnifier button:active, .app-notification button:active, .csd popover > contents.background.touch-selection button:checked:backdrop, .csd popover > contents.background.magnifier button:checked:backdrop, popover > contents.background.touch-selection button:checked:backdrop, popover > contents.background.magnifier button:checked:backdrop, .app-notification button:checked:backdrop, .csd popover > contents.background.touch-selection button:checked, .csd popover > contents.background.magnifier button:checked, popover > contents.background.touch-selection button:checked, popover > contents.background.magnifier button:checked, .app-notification button:checked, .osd button:active:backdrop, .osd button:active, .osd button:checked:backdrop, .osd button:checked { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); }
+.csd popover.background > contents.touch-selection button:active:backdrop, .csd popover.background > contents.magnifier button:active:backdrop, popover.background > contents.touch-selection button:active:backdrop, popover.background > contents.magnifier button:active:backdrop, .app-notification button:active:backdrop, .csd popover.background > contents.touch-selection button:active, .csd popover.background > contents.magnifier button:active, popover.background > contents.touch-selection button:active, popover.background > contents.magnifier button:active, .app-notification button:active, .csd popover.background > contents.touch-selection button:checked:backdrop, .csd popover.background > contents.magnifier button:checked:backdrop, popover.background > contents.touch-selection button:checked:backdrop, popover.background > contents.magnifier button:checked:backdrop, .app-notification button:checked:backdrop, .csd popover.background > contents.touch-selection button:checked, .csd popover.background > contents.magnifier button:checked, popover.background > contents.touch-selection button:checked, popover.background > contents.magnifier button:checked, .app-notification button:checked, .osd button:active:backdrop, .osd button:active, .osd button:checked:backdrop, .osd button:checked { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); }

-.csd popover > contents.background.touch-selection button:disabled:backdrop, .csd popover > contents.background.magnifier button:disabled:backdrop, popover > contents.background.touch-selection button:disabled:backdrop, popover > contents.background.magnifier button:disabled:backdrop, .app-notification button:disabled:backdrop, .csd popover > contents.background.touch-selection button:disabled, .csd popover > contents.background.magnifier button:disabled, popover > contents.background.touch-selection button:disabled, popover > contents.background.magnifier button:disabled, .app-notification button:disabled, .osd button:disabled:backdrop, .osd button:disabled { color: #8a8a89; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(58, 58, 57, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }
+.csd popover.background > contents.touch-selection button:disabled:backdrop, .csd popover.background > contents.magnifier button:disabled:backdrop, popover.background > contents.touch-selection button:disabled:backdrop, popover.background > contents.magnifier button:disabled:backdrop, .app-notification button:disabled:backdrop, .csd popover.background > contents.touch-selection button:disabled, .csd popover.background > contents.magnifier button:disabled, popover.background > contents.touch-selection button:disabled, popover.background > contents.magnifier button:disabled, .app-notification button:disabled, .osd button:disabled:backdrop, .osd button:disabled { color: #8a8a89; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(58, 58, 57, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }

-.csd popover > contents.background.touch-selection button:backdrop, .csd popover > contents.background.magnifier button:backdrop, popover > contents.background.touch-selection button:backdrop, popover > contents.background.magnifier button:backdrop, .app-notification button:backdrop, .osd button:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }
+.csd popover.background > contents.touch-selection button:backdrop, .csd popover.background > contents.magnifier button:backdrop, popover.background > contents.touch-selection button:backdrop, popover.background > contents.magnifier button:backdrop, .app-notification button:backdrop, .osd button:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }

-.csd popover > contents.background.touch-selection button.flat, .csd popover > contents.background.magnifier button.flat, popover > contents.background.touch-selection button.flat, popover > contents.background.magnifier button.flat, .app-notification button.flat, .osd button.flat { border-color: transparent; background-color: transparent; background-image: none; box-shadow: inset 0 1px rgba(255, 255, 255, 0); text-shadow: none; -gtk-icon-shadow: none; box-shadow: none; text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; }
+.csd popover.background > contents.touch-selection button.flat, .csd popover.background > contents.magnifier button.flat, popover.background > contents.touch-selection button.flat, popover.background > contents.magnifier button.flat, .app-notification button.flat, .osd button.flat { border-color: transparent; background-color: transparent; background-image: none; box-shadow: inset 0 1px rgba(255, 255, 255, 0); text-shadow: none; -gtk-icon-shadow: none; box-shadow: none; text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; }

-.csd popover > contents.background.touch-selection button.flat:hover, .csd popover > contents.background.magnifier button.flat:hover, popover > contents.background.touch-selection button.flat:hover, popover > contents.background.magnifier button.flat:hover, .app-notification button.flat:hover, .osd button.flat:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(68, 68, 68, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }
+.csd popover.background > contents.touch-selection button.flat:hover, .csd popover.background > contents.magnifier button.flat:hover, popover.background > contents.touch-selection button.flat:hover, popover.background > contents.magnifier button.flat:hover, .app-notification button.flat:hover, .osd button.flat:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(68, 68, 68, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }

-.csd popover > contents.background.touch-selection button.flat:disabled, .csd popover > contents.background.magnifier button.flat:disabled, popover > contents.background.touch-selection button.flat:disabled, popover > contents.background.magnifier button.flat:disabled, .app-notification button.flat:disabled, .osd button.flat:disabled { color: #8a8a89; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(58, 58, 57, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; background-image: none; border-color: transparent; box-shadow: none; }
+.csd popover.background > contents.touch-selection button.flat:disabled, .csd popover.background > contents.magnifier button.flat:disabled, popover.background > contents.touch-selection button.flat:disabled, popover.background > contents.magnifier button.flat:disabled, .app-notification button.flat:disabled, .osd button.flat:disabled { color: #8a8a89; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(58, 58, 57, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; background-image: none; border-color: transparent; box-shadow: none; }

-.csd popover > contents.background.touch-selection button.flat:backdrop, .csd popover > contents.background.magnifier button.flat:backdrop, popover > contents.background.touch-selection button.flat:backdrop, popover > contents.background.magnifier button.flat:backdrop, .app-notification button.flat:backdrop, .osd button.flat:backdrop { border-color: transparent; background-color: transparent; background-image: none; box-shadow: inset 0 1px rgba(255, 255, 255, 0); text-shadow: none; -gtk-icon-shadow: none; }
+.csd popover.background > contents.touch-selection button.flat:backdrop, .csd popover.background > contents.magnifier button.flat:backdrop, popover.background > contents.touch-selection button.flat:backdrop, popover.background > contents.magnifier button.flat:backdrop, .app-notification button.flat:backdrop, .osd button.flat:backdrop { border-color: transparent; background-color: transparent; background-image: none; box-shadow: inset 0 1px rgba(255, 255, 255, 0); text-shadow: none; -gtk-icon-shadow: none; }

-.csd popover > contents.background.touch-selection button.flat:active, .csd popover > contents.background.magnifier button.flat:active, popover > contents.background.touch-selection button.flat:active, popover > contents.background.magnifier button.flat:active, .app-notification button.flat:active, .csd popover > contents.background.touch-selection button.flat:checked, .csd popover > contents.background.magnifier button.flat:checked, popover > contents.background.touch-selection button.flat:checked, popover > contents.background.magnifier button.flat:checked, .app-notification button.flat:checked, .osd button.flat:active, .osd button.flat:checked { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); }
+.csd popover.background > contents.touch-selection button.flat:active, .csd popover.background > contents.magnifier button.flat:active, popover.background > contents.touch-selection button.flat:active, popover.background > contents.magnifier button.flat:active, .app-notification button.flat:active, .csd popover.background > contents.touch-selection button.flat:checked, .csd popover.background > contents.magnifier button.flat:checked, popover.background > contents.touch-selection button.flat:checked, popover.background > contents.magnifier button.flat:checked, .app-notification button.flat:checked, .osd button.flat:active, .osd button.flat:checked { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); }

 button.suggested-action { color: white; outline-color: rgba(255, 255, 255, 0.3); border-color: #0f3b71; border-bottom-color: #092444; background-image: linear-gradient(to top, #155099 2px, #15539e); text-shadow: 0 -1px rgba(0, 0, 0, 0.719216); -gtk-icon-shadow: 0 -1px rgba(0, 0, 0, 0.719216); box-shadow: inset 0 1px rgba(255, 255, 255, 0.02), 0 1px 2px rgba(0, 0, 0, 0.07); }

@@ -497,7 +497,7 @@ button:link > label:active, button:visited > label:active, *:link:active, button

 *:selected button:link > label:active, *:selected button:visited > label:active, *:selected *:link:active, *:selected button:active:link, *:selected button:active:visited { color: #d0ddec; }

-button:link > label:disabled, button:visited > label:disabled, button:link > label:disabled:backdrop, button:visited > label:disabled:backdrop, *:link:disabled, button:disabled:link, button:disabled:visited, *:link:disabled:backdrop, button:disabled:backdrop:link, button:disabled:backdrop:visited { color: rgba(141, 141, 141, 0.8); }
+button:link > label:disabled, button:visited > label:disabled, button:link > label:disabled:backdrop, button:visited > label:disabled:backdrop, *:link:disabled, button:disabled:link, button:disabled:visited, *:link:disabled:backdrop, button:disabled:backdrop:link, button:disabled:backdrop:visited { color: rgba(140, 140, 141, 0.8); }

 button:link > label:backdrop:backdrop:hover, button:visited > label:backdrop:backdrop:hover, button:link > label:backdrop:backdrop:hover:selected, button:visited > label:backdrop:backdrop:hover:selected, button:link > label:backdrop, button:visited > label:backdrop, *:link:backdrop:backdrop:hover, button:backdrop:backdrop:hover:link, button:backdrop:backdrop:hover:visited, *:link:backdrop:backdrop:hover:selected, button:backdrop:backdrop:hover:selected:link, button:backdrop:backdrop:hover:selected:visited, .selection-mode .titlebar:not(headerbar) .subtitle:backdrop:backdrop:hover:link, .selection-mode.titlebar:not(headerbar) .subtitle:backdrop:backdrop:hover:link, .selection-mode headerbar .subtitle:backdrop:backdrop:hover:link, headerbar.selection-mode .subtitle:backdrop:backdrop:hover:link, *:link:backdrop, button:backdrop:link, button:backdrop:visited { color: #15539e; }

@@ -564,7 +564,7 @@ spinbutton.vertical button.up { border-bottom-style: none; border-bottom-left-ra

 spinbutton.vertical button.down { border-top-style: none; border-top-left-radius: 0; border-top-right-radius: 0; }

-.osd spinbutton.vertical button:first-child { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }
+.osd spinbutton.vertical button:first-child { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }

 .osd spinbutton.vertical button:first-child:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(68, 68, 68, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }

@@ -572,7 +572,7 @@ spinbutton.vertical button.down { border-top-style: none; border-top-left-radius

 .osd spinbutton.vertical button:first-child:disabled { color: #8a8a89; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(58, 58, 57, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }

-.osd spinbutton.vertical button:first-child:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }
+.osd spinbutton.vertical button:first-child:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }

 treeview spinbutton:not(.vertical) { min-height: 0; border-style: none; border-radius: 0; }

@@ -590,7 +590,7 @@ toolbar { padding: 4px 3px 3px 4px; }

 .osd toolbar { background-color: transparent; }

-toolbar.osd { padding: 13px; border: none; border-radius: 5px; background-color: rgba(38, 38, 38, 0.7); }
+toolbar.osd { padding: 13px; border: none; border-radius: 5px; background-color: rgba(37, 37, 38, 0.7); }

 toolbar.osd.left, toolbar.osd.right, toolbar.osd.top, toolbar.osd.bottom { border-radius: 0; }

@@ -613,7 +613,7 @@ searchbar > revealer > box { padding: 6px; border-width: 0 0 1px; }
 .inline-toolbar:backdrop, .location-bar:backdrop, searchbar > revealer > box:backdrop { border-color: #202020; background-color: #2e2e2e; box-shadow: none; transition: 200ms ease-out; }

 /*************** Header bars * */
-.titlebar:not(headerbar), headerbar { padding: 0 6px; min-height: 46px; border-width: 0 0 1px; border-style: solid; border-color: #070707; border-radius: 0; background: #1b1b1b linear-gradient(to top, #262626, #2b2b2b); box-shadow: inset 0 1px rgba(238, 238, 236, 0.07); /* Darken switchbuttons for headerbars. issue #1588 */ /* hide the close button separator */ }
+.titlebar:not(headerbar), headerbar { padding: 0 6px; min-height: 46px; border-width: 0 0 1px; border-style: solid; border-color: #070707; border-radius: 0; background: #1b1b1b linear-gradient(to top, #252526, #2b2b2b); box-shadow: inset 0 1px rgba(238, 238, 236, 0.07); /* Darken switchbuttons for headerbars. issue #1588 */ /* hide the close button separator */ }

 .titlebar:backdrop:not(headerbar), headerbar:backdrop { border-color: #202020; background-color: #353535; background-image: none; box-shadow: inset 0 1px rgba(238, 238, 236, 0.07); transition: 200ms ease-out; }

@@ -879,19 +879,19 @@ popover.menu > arrow, popover > arrow { background-color: #353535; border: 1px s

 popover > contents { padding: 8px; background-color: #353535; border: 1px solid #1b1b1b; margin: 0px; }

-popover > contents.background { background-color: #353535; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.3); }
+popover.background > contents { background-color: #353535; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.3); }

-.csd popover > contents.background, popover > contents.background { border: 1px solid #1b1b1b; border-radius: 9px; }
+.csd popover.background > contents, popover.background > contents { border: 1px solid #1b1b1b; border-radius: 9px; }

-popover > contents.background:backdrop { background-color: #353535; box-shadow: none; }
+popover.background > contents:backdrop { background-color: #353535; box-shadow: none; }

-popover > contents.background > list, popover > contents.background > .view, popover > contents.background > iconview, popover > contents.background > toolbar { border-style: none; background-color: transparent; }
+popover.background > contents > list, popover.background > contents > .view, popover.background > contents > iconview, popover.background > contents > toolbar { border-style: none; background-color: transparent; }

-.csd popover > contents.background.touch-selection, .csd popover > contents.background.magnifier, popover > contents.background.touch-selection, popover > contents.background.magnifier { border: 1px solid rgba(255, 255, 255, 0.1); }
+.csd popover.background > contents.touch-selection, .csd popover.background > contents.magnifier, popover.background > contents.touch-selection, popover.background > contents.magnifier { border: 1px solid rgba(255, 255, 255, 0.1); }

-popover > contents.background separator { margin: 3px; }
+popover.background > contents separator { margin: 3px; }

-popover > contents.background list separator { margin: 0px; }
+popover.background > contents list separator { margin: 0px; }

 /************* Notebooks * */
 notebook box > header { padding: 1px; border-color: #1b1b1b; border-width: 1px; background-color: #282828; }
@@ -1141,7 +1141,7 @@ switch:backdrop:disabled slider label, switch:backdrop:disabled slider { color:

 .view.content-view.check:active:not(list), iconview.content-view.check:active:not(list), .content-view .tile check:active:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: transparent; background-color: rgba(21, 83, 158, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: none; -gtk-icon-shadow: none; }

-.view.content-view.check:backdrop:not(list), iconview.content-view.check:backdrop:not(list), .content-view .tile check:backdrop:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: transparent; background-color: rgba(90, 90, 90, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: none; -gtk-icon-shadow: none; }
+.view.content-view.check:backdrop:not(list), iconview.content-view.check:backdrop:not(list), .content-view .tile check:backdrop:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: transparent; background-color: rgba(89, 89, 90, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: none; -gtk-icon-shadow: none; }

 .view.content-view.check:checked:not(list), iconview.content-view.check:checked:not(list), .content-view .tile check:checked:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: #eeeeec; background-color: rgba(21, 83, 158, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: -gtk-icontheme('object-select-symbolic'); -gtk-icon-shadow: none; }

@@ -1149,7 +1149,7 @@ switch:backdrop:disabled slider label, switch:backdrop:disabled slider { color:

 .view.content-view.check:checked:active:not(list), iconview.content-view.check:checked:active:not(list), .content-view .tile check:checked:active:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: #eeeeec; background-color: rgba(21, 83, 158, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: -gtk-icontheme('object-select-symbolic'); -gtk-icon-shadow: none; }

-.view.content-view.check:backdrop:checked:not(list), iconview.content-view.check:backdrop:checked:not(list), .content-view .tile check:backdrop:checked:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: rgba(238, 238, 236, 0.8); background-color: rgba(90, 90, 90, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: -gtk-icontheme('object-select-symbolic'); -gtk-icon-shadow: none; }
+.view.content-view.check:backdrop:checked:not(list), iconview.content-view.check:backdrop:checked:not(list), .content-view .tile check:backdrop:checked:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: rgba(238, 238, 236, 0.8); background-color: rgba(89, 89, 90, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: -gtk-icontheme('object-select-symbolic'); -gtk-icon-shadow: none; }

 checkbutton.text-button, radiobutton.text-button { padding: 2px 0; outline-offset: 0; }

@@ -1157,7 +1157,7 @@ checkbutton.text-button label:not(:only-child):first-child, radiobutton.text-but

 checkbutton.text-button label:not(:only-child):last-child, radiobutton.text-button label:not(:only-child):last-child { margin-right: 4px; }

-check, radio { margin: 0 4px; min-height: 14px; min-width: 14px; border: 1px solid; -gtk-icon-source: none; color: #eeeeec; outline-color: rgba(238, 238, 236, 0.3); border-color: #070707; text-shadow: 0 -1px rgba(0, 0, 0, 0.834353); -gtk-icon-shadow: 0 -1px rgba(0, 0, 0, 0.834353); background-image: linear-gradient(to bottom, #2d2d2d 20%, #262626 90%); box-shadow: inset 0 1px rgba(255, 255, 255, 0.02), 0 1px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.07); }
+check, radio { margin: 0 4px; min-height: 14px; min-width: 14px; border: 1px solid; -gtk-icon-source: none; color: #eeeeec; outline-color: rgba(238, 238, 236, 0.3); border-color: #070707; text-shadow: 0 -1px rgba(0, 0, 0, 0.834353); -gtk-icon-shadow: 0 -1px rgba(0, 0, 0, 0.834353); background-image: linear-gradient(to bottom, #2d2d2d 20%, #252526 90%); box-shadow: inset 0 1px rgba(255, 255, 255, 0.02), 0 1px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.07); }

 check:only-child, radio:only-child { margin: 0; }

@@ -1181,13 +1181,13 @@ check:backdrop:disabled, radio:backdrop:disabled { border-color: #202020; backgr

 check:backdrop:disabled label, check:backdrop:disabled, radio:backdrop:disabled label, radio:backdrop:disabled { color: #5b5b5b; }

-.osd check, .osd radio { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }
+.osd check, .osd radio { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }

-.osd check:hover, .osd radio:hover { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }
+.osd check:hover, .osd radio:hover { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }

 .osd check:active, .osd radio:active { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); }

-.osd check:backdrop, .osd radio:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }
+.osd check:backdrop, .osd radio:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }

 .osd check:disabled, .osd radio:disabled { color: #8a8a89; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(58, 58, 57, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }

@@ -1280,7 +1280,7 @@ scale fill:disabled:backdrop, scale fill:disabled { border-color: transparent; b

 .osd scale fill:disabled:backdrop, .osd scale fill:disabled { border-color: transparent; background-color: transparent; }

-scale slider { color: #eeeeec; outline-color: rgba(238, 238, 236, 0.3); border-color: #070707; text-shadow: 0 -1px rgba(0, 0, 0, 0.834353); -gtk-icon-shadow: 0 -1px rgba(0, 0, 0, 0.834353); background-image: linear-gradient(to bottom, #2d2d2d 20%, #262626 90%); box-shadow: inset 0 1px rgba(255, 255, 255, 0.02), 0 1px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.07); border: 1px solid black; border-radius: 100%; transition: all 200ms cubic-bezier(0.25, 0.46, 0.45, 0.94); transition-property: background, border, box-shadow; }
+scale slider { color: #eeeeec; outline-color: rgba(238, 238, 236, 0.3); border-color: #070707; text-shadow: 0 -1px rgba(0, 0, 0, 0.834353); -gtk-icon-shadow: 0 -1px rgba(0, 0, 0, 0.834353); background-image: linear-gradient(to bottom, #2d2d2d 20%, #252526 90%); box-shadow: inset 0 1px rgba(255, 255, 255, 0.02), 0 1px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.07); border: 1px solid black; border-radius: 100%; transition: all 200ms cubic-bezier(0.25, 0.46, 0.45, 0.94); transition-property: background, border, box-shadow; }

 scale slider:hover { color: #eeeeec; outline-color: rgba(238, 238, 236, 0.3); border-color: #070707; box-shadow: inset 0 1px rgba(255, 255, 255, 0.02), 0 1px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.07); background-image: linear-gradient(to bottom, #353535 20%, #2b2b2b 90%); }

@@ -1300,17 +1300,17 @@ scale slider:backdrop:disabled label, scale slider:backdrop:disabled { color: #5

 row:selected scale slider:disabled, row:selected scale slider { border-color: #030c17; }

-.osd scale slider { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); border-color: rgba(0, 0, 0, 0.7); background-color: #262626; }
+.osd scale slider { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); border-color: rgba(0, 0, 0, 0.7); background-color: #252526; }

-.osd scale slider:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(68, 68, 68, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); background-color: #262626; }
+.osd scale slider:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(68, 68, 68, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); background-color: #252526; }

-.osd scale slider:active { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); background-color: #262626; }
+.osd scale slider:active { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); background-color: #252526; }

-.osd scale slider:disabled { color: #8a8a89; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(58, 58, 57, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; background-color: #262626; }
+.osd scale slider:disabled { color: #8a8a89; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(58, 58, 57, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; background-color: #252526; }

-.osd scale slider:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(38, 38, 38, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; background-color: #262626; }
+.osd scale slider:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(37, 37, 38, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; background-color: #252526; }

-.osd scale slider:backdrop:disabled { background-color: #262626; }
+.osd scale slider:backdrop:disabled { background-color: #252526; }

 scale value { color: alpha(currentColor,0.55); }

@@ -1636,7 +1636,7 @@ row.activatable:selected.has-open-popup, row.activatable:selected:hover { backgr
 row.activatable:selected:backdrop { background-color: #15539e; }

 /********************* App Notifications * */
-.app-notification, .app-notification.frame { padding: 10px; border-radius: 0 0 5px 5px; background-color: rgba(38, 38, 38, 0.7); background-image: linear-gradient(to bottom, rgba(0, 0, 0, 0.2), transparent 2px); background-clip: padding-box; }
+.app-notification, .app-notification.frame { padding: 10px; border-radius: 0 0 5px 5px; background-color: rgba(37, 37, 38, 0.7); background-image: linear-gradient(to bottom, rgba(0, 0, 0, 0.2), transparent 2px); background-clip: padding-box; }

 .app-notification:backdrop, .app-notification.frame:backdrop { background-image: none; transition: 200ms ease-out; }

@@ -2063,7 +2063,7 @@ popover.menu box.inline-buttons { border-radius: 5px; border-style: none; border

 popover.menu box.circular-buttons { padding-bottom: 5px; }

-popover.menu.background contents { background: white; }
+popover.menu arrow, popover.menu.background contents { background-color: #2f2f2f; }

 popover.menu.background separator { margin: 5px 0px; }

@@ -82,9 +82,9 @@ assistant .sidebar label { padding: 6px 12px; }

 assistant .sidebar label.highlight { background-color: #cecece; }

-.csd popover > contents.background.touch-selection, .csd popover > contents.background.magnifier, popover > contents.background.touch-selection, popover > contents.background.magnifier, .csd popover > contents.background.osd, popover > contents.background.osd, .app-notification, .app-notification.frame, .osd .scale-popup, .osd { color: #eeeeec; border: none; background-color: rgba(53, 53, 53, 0.7); background-clip: padding-box; text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; }
+.csd popover.background > contents.touch-selection, .csd popover.background > contents.magnifier, popover.background > contents.touch-selection, popover.background > contents.magnifier, .csd popover.background > contents.osd, popover.background > contents.osd, .app-notification, .app-notification.frame, .osd .scale-popup, .osd { color: #eeeeec; border: none; background-color: rgba(53, 53, 53, 0.7); background-clip: padding-box; text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; }

-.csd popover > contents.background.touch-selection:backdrop, .csd popover > contents.background.magnifier:backdrop, popover > contents.background.touch-selection:backdrop, popover > contents.background.magnifier:backdrop, .csd popover > contents.background.osd:backdrop, popover > contents.background.osd:backdrop, .app-notification:backdrop, .osd .scale-popup:backdrop, .osd:backdrop { text-shadow: none; -gtk-icon-shadow: none; }
+.csd popover.background > contents.touch-selection:backdrop, .csd popover.background > contents.magnifier:backdrop, popover.background > contents.touch-selection:backdrop, popover.background > contents.magnifier:backdrop, .csd popover.background > contents.osd:backdrop, popover.background > contents.osd:backdrop, .app-notification:backdrop, .osd .scale-popup:backdrop, .osd:backdrop { text-shadow: none; -gtk-icon-shadow: none; }

 /********************* Spinner Animation * */
@keyframes spin { to { -gtk-icon-transform: rotate(1turn); } }
@@ -279,25 +279,25 @@ button.osd:disabled:backdrop, button.osd:disabled { color: #919190; border-color

 button.osd:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(53, 53, 53, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; border: none; }

-.csd popover > contents.background.touch-selection button, .csd popover > contents.background.magnifier button, popover > contents.background.touch-selection button, popover > contents.background.magnifier button, .app-notification button, .app-notification.frame button, .osd button { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(53, 53, 53, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }
+.csd popover.background > contents.touch-selection button, .csd popover.background > contents.magnifier button, popover.background > contents.touch-selection button, popover.background > contents.magnifier button, .app-notification button, .app-notification.frame button, .osd button { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(53, 53, 53, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }

-.csd popover > contents.background.touch-selection button:hover, .csd popover > contents.background.magnifier button:hover, popover > contents.background.touch-selection button:hover, popover > contents.background.magnifier button:hover, .app-notification button:hover, .osd button:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(83, 83, 83, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }
+.csd popover.background > contents.touch-selection button:hover, .csd popover.background > contents.magnifier button:hover, popover.background > contents.touch-selection button:hover, popover.background > contents.magnifier button:hover, .app-notification button:hover, .osd button:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(83, 83, 83, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }

-.csd popover > contents.background.touch-selection button:active:backdrop, .csd popover > contents.background.magnifier button:active:backdrop, popover > contents.background.touch-selection button:active:backdrop, popover > contents.background.magnifier button:active:backdrop, .app-notification button:active:backdrop, .csd popover > contents.background.touch-selection button:active, .csd popover > contents.background.magnifier button:active, popover > contents.background.touch-selection button:active, popover > contents.background.magnifier button:active, .app-notification button:active, .csd popover > contents.background.touch-selection button:checked:backdrop, .csd popover > contents.background.magnifier button:checked:backdrop, popover > contents.background.touch-selection button:checked:backdrop, popover > contents.background.magnifier button:checked:backdrop, .app-notification button:checked:backdrop, .csd popover > contents.background.touch-selection button:checked, .csd popover > contents.background.magnifier button:checked, popover > contents.background.touch-selection button:checked, popover > contents.background.magnifier button:checked, .app-notification button:checked, .osd button:active:backdrop, .osd button:active, .osd button:checked:backdrop, .osd button:checked { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); }
+.csd popover.background > contents.touch-selection button:active:backdrop, .csd popover.background > contents.magnifier button:active:backdrop, popover.background > contents.touch-selection button:active:backdrop, popover.background > contents.magnifier button:active:backdrop, .app-notification button:active:backdrop, .csd popover.background > contents.touch-selection button:active, .csd popover.background > contents.magnifier button:active, popover.background > contents.touch-selection button:active, popover.background > contents.magnifier button:active, .app-notification button:active, .csd popover.background > contents.touch-selection button:checked:backdrop, .csd popover.background > contents.magnifier button:checked:backdrop, popover.background > contents.touch-selection button:checked:backdrop, popover.background > contents.magnifier button:checked:backdrop, .app-notification button:checked:backdrop, .csd popover.background > contents.touch-selection button:checked, .csd popover.background > contents.magnifier button:checked, popover.background > contents.touch-selection button:checked, popover.background > contents.magnifier button:checked, .app-notification button:checked, .osd button:active:backdrop, .osd button:active, .osd button:checked:backdrop, .osd button:checked { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); }

-.csd popover > contents.background.touch-selection button:disabled:backdrop, .csd popover > contents.background.magnifier button:disabled:backdrop, popover > contents.background.touch-selection button:disabled:backdrop, popover > contents.background.magnifier button:disabled:backdrop, .app-notification button:disabled:backdrop, .csd popover > contents.background.touch-selection button:disabled, .csd popover > contents.background.magnifier button:disabled, popover > contents.background.touch-selection button:disabled, popover > contents.background.magnifier button:disabled, .app-notification button:disabled, .osd button:disabled:backdrop, .osd button:disabled { color: #919190; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(71, 71, 71, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }
+.csd popover.background > contents.touch-selection button:disabled:backdrop, .csd popover.background > contents.magnifier button:disabled:backdrop, popover.background > contents.touch-selection button:disabled:backdrop, popover.background > contents.magnifier button:disabled:backdrop, .app-notification button:disabled:backdrop, .csd popover.background > contents.touch-selection button:disabled, .csd popover.background > contents.magnifier button:disabled, popover.background > contents.touch-selection button:disabled, popover.background > contents.magnifier button:disabled, .app-notification button:disabled, .osd button:disabled:backdrop, .osd button:disabled { color: #919190; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(71, 71, 71, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }

-.csd popover > contents.background.touch-selection button:backdrop, .csd popover > contents.background.magnifier button:backdrop, popover > contents.background.touch-selection button:backdrop, popover > contents.background.magnifier button:backdrop, .app-notification button:backdrop, .osd button:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(53, 53, 53, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }
+.csd popover.background > contents.touch-selection button:backdrop, .csd popover.background > contents.magnifier button:backdrop, popover.background > contents.touch-selection button:backdrop, popover.background > contents.magnifier button:backdrop, .app-notification button:backdrop, .osd button:backdrop { color: #eeeeec; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(53, 53, 53, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; }

-.csd popover > contents.background.touch-selection button.flat, .csd popover > contents.background.magnifier button.flat, popover > contents.background.touch-selection button.flat, popover > contents.background.magnifier button.flat, .app-notification button.flat, .osd button.flat { border-color: transparent; background-color: transparent; background-image: none; box-shadow: inset 0 1px rgba(255, 255, 255, 0); text-shadow: none; -gtk-icon-shadow: none; box-shadow: none; text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; }
+.csd popover.background > contents.touch-selection button.flat, .csd popover.background > contents.magnifier button.flat, popover.background > contents.touch-selection button.flat, popover.background > contents.magnifier button.flat, .app-notification button.flat, .osd button.flat { border-color: transparent; background-color: transparent; background-image: none; box-shadow: inset 0 1px rgba(255, 255, 255, 0); text-shadow: none; -gtk-icon-shadow: none; box-shadow: none; text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; }

-.csd popover > contents.background.touch-selection button.flat:hover, .csd popover > contents.background.magnifier button.flat:hover, popover > contents.background.touch-selection button.flat:hover, popover > contents.background.magnifier button.flat:hover, .app-notification button.flat:hover, .osd button.flat:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(83, 83, 83, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }
+.csd popover.background > contents.touch-selection button.flat:hover, .csd popover.background > contents.magnifier button.flat:hover, popover.background > contents.touch-selection button.flat:hover, popover.background > contents.magnifier button.flat:hover, .app-notification button.flat:hover, .osd button.flat:hover { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(83, 83, 83, 0.7)); background-clip: padding-box; box-shadow: inset 0 1px rgba(255, 255, 255, 0.1); text-shadow: 0 1px black; -gtk-icon-shadow: 0 1px black; outline-color: rgba(238, 238, 236, 0.3); }

-.csd popover > contents.background.touch-selection button.flat:disabled, .csd popover > contents.background.magnifier button.flat:disabled, popover > contents.background.touch-selection button.flat:disabled, popover > contents.background.magnifier button.flat:disabled, .app-notification button.flat:disabled, .osd button.flat:disabled { color: #919190; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(71, 71, 71, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; background-image: none; border-color: transparent; box-shadow: none; }
+.csd popover.background > contents.touch-selection button.flat:disabled, .csd popover.background > contents.magnifier button.flat:disabled, popover.background > contents.touch-selection button.flat:disabled, popover.background > contents.magnifier button.flat:disabled, .app-notification button.flat:disabled, .osd button.flat:disabled { color: #919190; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(71, 71, 71, 0.5)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; background-image: none; border-color: transparent; box-shadow: none; }

-.csd popover > contents.background.touch-selection button.flat:backdrop, .csd popover > contents.background.magnifier button.flat:backdrop, popover > contents.background.touch-selection button.flat:backdrop, popover > contents.background.magnifier button.flat:backdrop, .app-notification button.flat:backdrop, .osd button.flat:backdrop { border-color: transparent; background-color: transparent; background-image: none; box-shadow: inset 0 1px rgba(255, 255, 255, 0); text-shadow: none; -gtk-icon-shadow: none; }
+.csd popover.background > contents.touch-selection button.flat:backdrop, .csd popover.background > contents.magnifier button.flat:backdrop, popover.background > contents.touch-selection button.flat:backdrop, popover.background > contents.magnifier button.flat:backdrop, .app-notification button.flat:backdrop, .osd button.flat:backdrop { border-color: transparent; background-color: transparent; background-image: none; box-shadow: inset 0 1px rgba(255, 255, 255, 0); text-shadow: none; -gtk-icon-shadow: none; }

-.csd popover > contents.background.touch-selection button.flat:active, .csd popover > contents.background.magnifier button.flat:active, popover > contents.background.touch-selection button.flat:active, popover > contents.background.magnifier button.flat:active, .app-notification button.flat:active, .csd popover > contents.background.touch-selection button.flat:checked, .csd popover > contents.background.magnifier button.flat:checked, popover > contents.background.touch-selection button.flat:checked, popover > contents.background.magnifier button.flat:checked, .app-notification button.flat:checked, .osd button.flat:active, .osd button.flat:checked { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); }
+.csd popover.background > contents.touch-selection button.flat:active, .csd popover.background > contents.magnifier button.flat:active, popover.background > contents.touch-selection button.flat:active, popover.background > contents.magnifier button.flat:active, .app-notification button.flat:active, .csd popover.background > contents.touch-selection button.flat:checked, .csd popover.background > contents.magnifier button.flat:checked, popover.background > contents.touch-selection button.flat:checked, popover.background > contents.magnifier button.flat:checked, .app-notification button.flat:checked, .osd button.flat:active, .osd button.flat:checked { color: white; border-color: rgba(0, 0, 0, 0.7); background-color: transparent; background-image: image(rgba(0, 0, 0, 0.7)); background-clip: padding-box; box-shadow: none; text-shadow: none; -gtk-icon-shadow: none; outline-color: rgba(238, 238, 236, 0.3); }

 button.suggested-action { color: white; outline-color: rgba(255, 255, 255, 0.3); border-color: #1b6acb; border-bottom-color: #15539e; background-image: linear-gradient(to top, #2379e2 2px, #3584e4); text-shadow: 0 -1px rgba(0, 0, 0, 0.559216); -gtk-icon-shadow: 0 -1px rgba(0, 0, 0, 0.559216); box-shadow: inset 0 1px rgba(255, 255, 255, 0.2), 0 1px 2px rgba(0, 0, 0, 0.07); }

@@ -887,19 +887,19 @@ popover.menu > arrow, popover > arrow { background-color: #f6f5f4; border: 1px s

 popover > contents { padding: 8px; background-color: #f6f5f4; border: 1px solid #cdc7c2; margin: 0px; }

-popover > contents.background { background-color: #f6f5f4; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.3); }
+popover.background > contents { background-color: #f6f5f4; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.3); }

-.csd popover > contents.background, popover > contents.background { border: 1px solid #cdc7c2; border-radius: 9px; }
+.csd popover.background > contents, popover.background > contents { border: 1px solid #cdc7c2; border-radius: 9px; }

-popover > contents.background:backdrop { background-color: #f6f5f4; box-shadow: none; }
+popover.background > contents:backdrop { background-color: #f6f5f4; box-shadow: none; }

-popover > contents.background > list, popover > contents.background > .view, popover > contents.background > iconview, popover > contents.background > toolbar { border-style: none; background-color: transparent; }
+popover.background > contents > list, popover.background > contents > .view, popover.background > contents > iconview, popover.background > contents > toolbar { border-style: none; background-color: transparent; }

-.csd popover > contents.background.touch-selection, .csd popover > contents.background.magnifier, popover > contents.background.touch-selection, popover > contents.background.magnifier { border: 1px solid rgba(255, 255, 255, 0.1); }
+.csd popover.background > contents.touch-selection, .csd popover.background > contents.magnifier, popover.background > contents.touch-selection, popover.background > contents.magnifier { border: 1px solid rgba(255, 255, 255, 0.1); }

-popover > contents.background separator { margin: 3px; }
+popover.background > contents separator { margin: 3px; }

-popover > contents.background list separator { margin: 0px; }
+popover.background > contents list separator { margin: 0px; }

 /************* Notebooks * */
 notebook box > header { padding: 1px; border-color: #cdc7c2; border-width: 1px; background-color: #e1dedb; }
@@ -1155,7 +1155,7 @@ row:selected switch slider:checked, row:selected switch slider { border-color: #

 .view.content-view.check:active:not(list), iconview.content-view.check:active:not(list), .content-view .tile check:active:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: transparent; background-color: rgba(53, 132, 228, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: none; -gtk-icon-shadow: none; }

-.view.content-view.check:backdrop:not(list), iconview.content-view.check:backdrop:not(list), .content-view .tile check:backdrop:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: transparent; background-color: rgba(141, 141, 141, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: none; -gtk-icon-shadow: none; }
+.view.content-view.check:backdrop:not(list), iconview.content-view.check:backdrop:not(list), .content-view .tile check:backdrop:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: transparent; background-color: rgba(140, 140, 141, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: none; -gtk-icon-shadow: none; }

 .view.content-view.check:checked:not(list), iconview.content-view.check:checked:not(list), .content-view .tile check:checked:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: #eeeeec; background-color: rgba(53, 132, 228, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: -gtk-icontheme('object-select-symbolic'); -gtk-icon-shadow: none; }

@@ -1163,7 +1163,7 @@ row:selected switch slider:checked, row:selected switch slider { border-color: #

 .view.content-view.check:checked:active:not(list), iconview.content-view.check:checked:active:not(list), .content-view .tile check:checked:active:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: #eeeeec; background-color: rgba(53, 132, 228, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: -gtk-icontheme('object-select-symbolic'); -gtk-icon-shadow: none; }

-.view.content-view.check:backdrop:checked:not(list), iconview.content-view.check:backdrop:checked:not(list), .content-view .tile check:backdrop:checked:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: rgba(238, 238, 236, 0.8); background-color: rgba(141, 141, 141, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: -gtk-icontheme('object-select-symbolic'); -gtk-icon-shadow: none; }
+.view.content-view.check:backdrop:checked:not(list), iconview.content-view.check:backdrop:checked:not(list), .content-view .tile check:backdrop:checked:not(list) { margin: 4px; min-width: 32px; min-height: 32px; color: rgba(238, 238, 236, 0.8); background-color: rgba(140, 140, 141, 0.95); border-radius: 5px; background-image: none; transition: 200ms; box-shadow: none; border-width: 0; -gtk-icon-source: -gtk-icontheme('object-select-symbolic'); -gtk-icon-shadow: none; }

 checkbutton.text-button, radiobutton.text-button { padding: 2px 0; outline-offset: 0; }

@@ -2079,7 +2079,7 @@ popover.menu box.inline-buttons { border-radius: 5px; border-style: none; border

 popover.menu box.circular-buttons { padding-bottom: 5px; }

-popover.menu.background contents { background: white; }
+popover.menu arrow, popover.menu.background contents { background-color: #ffffff; }

 popover.menu.background separator { margin: 5px 0px; }

@@ -827,7 +827,7 @@ summary = [
  '    Colord support: @0@'.format(get_option('colord')),
  '          Profiler: @0@'.format(get_option('profiler')),
  '     Introspection: @0@'.format(get_option('introspection')),
-  '     Documentation: @0@'.format(get_option('documentation')),
+  '     Documentation: @0@'.format(get_option('gtk_doc')),
  '         Man pages: @0@'.format(get_option('man-pages')),
  '       Build tests: @0@'.format(get_option('build-tests')),
  '     Install tests: @0@'.format(get_option('install-tests')),
@@ -31,7 +31,7 @@ option('colord', type: 'combo', choices : ['yes', 'no', 'auto'], value : 'auto',
  description : 'Build colord support for the CUPS printing backend')

 # Documentation and introspection
-option('documentation', type: 'boolean', value: 'false',
+option('gtk_doc', type: 'boolean', value: 'false',
  description : 'Build API reference and tools documentation')
 option('man-pages', type: 'boolean', value: 'false',
  description : 'Build man pages for installed tools')
@@ -709,13 +709,7 @@ _post_send (GtkCupsRequest *request)
  httpClearFields (request->http);
  httpSetField (request->http, HTTP_FIELD_CONTENT_LENGTH, length);
  httpSetField (request->http, HTTP_FIELD_CONTENT_TYPE, "application/ipp");
-#ifdef HAVE_HTTPGETAUTHSTRING
  httpSetField (request->http, HTTP_FIELD_AUTHORIZATION, httpGetAuthString (request->http));
-#else
-#ifdef HAVE_HTTP_AUTHSTRING
-  httpSetField (request->http, HTTP_FIELD_AUTHORIZATION, request->http->authstring);
-#endif
-#endif

  if (httpPost (request->http, request->resource))
    {
@@ -1198,13 +1192,7 @@ _get_send (GtkCupsRequest *request)
    }

  httpClearFields (request->http);
-#ifdef HAVE_HTTPGETAUTHSTRING
  httpSetField (request->http, HTTP_FIELD_AUTHORIZATION, httpGetAuthString (request->http));
-#else
-#ifdef HAVE_HTTP_AUTHSTRING
-  httpSetField (request->http, HTTP_FIELD_AUTHORIZATION, request->http->authstring);
-#endif
-#endif

  if (httpGet (request->http, request->resource))
    {
@@ -17,32 +17,8 @@ print_backends = ['file']
 # Checks to see if we should compile with CUPS backend for GTK
 enable_cups = enabled_print_backends.contains('cups')
 if enable_cups
-  #cups_config = find_program('cups-config', required : true)
-  #if cups_config.found()
-  # FIXME: eek, see configure.ac (we're just not going to support non-standar prefix for now)
-  #endif
-  if cc.has_header('cups/cups.h')
-    # TODO: include_directories from cups-config
-    cups_major_version = cc.compute_int('CUPS_VERSION_MAJOR', prefix : '#include <cups/cups.h>')
-    cups_minor_version = cc.compute_int('CUPS_VERSION_MINOR', prefix : '#include <cups/cups.h>')
-    message('Found CUPS version: @0@.@1@'.format(cups_major_version, cups_minor_version))
-    if cups_major_version >= 2
-      if cc.compiles('#include <cups/http.h> \n http_t http; char *s = http.authstring;')
-        cdata.set('HAVE_HTTP_AUTHSTRING', 1,
-          description :'Define if cups http_t authstring field is accessible')
-      endif
-      libcups = cc.find_library('cups', required : true)
-      if libcups.found() and cc.has_function('httpGetAuthString', dependencies : libcups)
-        cdata.set('HAVE_HTTPGETAUTHSTRING', 1)
-      endif
-
-      print_backends += ['cups']
-    else
-      error('Need CUPS version >= 2.0')
-    endif
-  else
-    error('Cannot find CUPS headers in default prefix.')
-  endif
+  cups_dep = dependency('cups', version : '>=2.0', required: true)
+  print_backends += ['cups']
 endif

 # Checks to see if we should compile with cloudprint backend for GTK
@@ -101,7 +77,7 @@ if print_backends.contains('cups')
                'gtkcupsutils.c',
                'gtkcupssecretsutils.c',
                c_args: printbackends_args,
-                dependencies: [libgtk_dep, libcups, colord_dep],
+                dependencies: [libgtk_dep, cups_dep, colord_dep],
                install_dir: printbackends_install_dir,
                install : true)
 endif
@@ -0,0 +1,380 @@
+#include <locale.h>
+
+#include "../../gtk/gtkconstrainttypesprivate.h"
+#include "../../gtk/gtkconstraintsolverprivate.h"
+#include "../../gtk/gtkconstraintexpressionprivate.h"
+
+static void
+constraint_solver_simple (void)
+{
+  GtkConstraintSolver *solver = gtk_constraint_solver_new ();
+
+  GtkConstraintVariable *x = gtk_constraint_solver_create_variable (solver, NULL, "x", 167.0);
+  GtkConstraintVariable *y = gtk_constraint_solver_create_variable (solver, NULL, "y", 2.0);
+
+  GtkConstraintExpression *e = gtk_constraint_expression_new_from_variable (y);
+
+  gtk_constraint_solver_add_constraint (solver,
+                                        x, GTK_CONSTRAINT_RELATION_EQ, e,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  double x_value = gtk_constraint_variable_get_value (x);
+  double y_value = gtk_constraint_variable_get_value (y);
+
+  g_assert_cmpfloat_with_epsilon (x_value, y_value, 0.001);
+  g_assert_cmpfloat_with_epsilon (x_value, 0.0, 0.001);
+  g_assert_cmpfloat_with_epsilon (y_value, 0.0, 0.001);
+
+  gtk_constraint_variable_unref (y);
+  gtk_constraint_variable_unref (x);
+
+  g_object_unref (solver);
+}
+
+static void
+constraint_solver_stay (void)
+{
+  GtkConstraintSolver *solver = gtk_constraint_solver_new ();
+
+  GtkConstraintVariable *x = gtk_constraint_solver_create_variable (solver, NULL, "x", 5.0);
+  GtkConstraintVariable *y = gtk_constraint_solver_create_variable (solver, NULL, "y", 10.0);
+
+  gtk_constraint_solver_add_stay_variable (solver, x, GTK_CONSTRAINT_STRENGTH_WEAK);
+  gtk_constraint_solver_add_stay_variable (solver, y, GTK_CONSTRAINT_STRENGTH_WEAK);
+
+  double x_value = gtk_constraint_variable_get_value (x);
+  double y_value = gtk_constraint_variable_get_value (y);
+
+  g_assert_cmpfloat_with_epsilon (x_value, 5.0, 0.001);
+  g_assert_cmpfloat_with_epsilon (y_value, 10.0, 0.001);
+
+  gtk_constraint_variable_unref (x);
+  gtk_constraint_variable_unref (y);
+
+  g_object_unref (solver);
+}
+
+static void
+constraint_solver_variable_geq_constant (void)
+{
+  GtkConstraintSolver *solver = gtk_constraint_solver_new ();
+
+  GtkConstraintVariable *x = gtk_constraint_solver_create_variable (solver, NULL, "x", 10.0);
+  GtkConstraintExpression *e = gtk_constraint_expression_new (100.0);
+
+  gtk_constraint_solver_add_constraint (solver,
+                                        x, GTK_CONSTRAINT_RELATION_GE, e,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  double x_value = gtk_constraint_variable_get_value (x);
+
+  g_assert_cmpfloat (x_value, >=, 100.0);
+
+  gtk_constraint_variable_unref (x);
+
+  g_object_unref (solver);
+}
+
+static void
+constraint_solver_variable_leq_constant (void)
+{
+  GtkConstraintSolver *solver = gtk_constraint_solver_new ();
+
+  GtkConstraintVariable *x = gtk_constraint_solver_create_variable (solver, NULL, "x", 100.0);
+  GtkConstraintExpression *e = gtk_constraint_expression_new (10.0);
+
+  gtk_constraint_solver_add_constraint (solver,
+                                        x, GTK_CONSTRAINT_RELATION_LE, e,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  double x_value = gtk_constraint_variable_get_value (x);
+
+  g_assert_cmpfloat (x_value, <=, 10.0);
+
+  gtk_constraint_variable_unref (x);
+
+  g_object_unref (solver);
+}
+
+static void
+constraint_solver_variable_eq_constant (void)
+{
+  GtkConstraintSolver *solver = gtk_constraint_solver_new ();
+
+  GtkConstraintVariable *x = gtk_constraint_solver_create_variable (solver, NULL, "x", 10.0);
+  GtkConstraintExpression *e = gtk_constraint_expression_new (100.0);
+
+  gtk_constraint_solver_add_constraint (solver,
+                                        x, GTK_CONSTRAINT_RELATION_EQ, e,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  double x_value = gtk_constraint_variable_get_value (x);
+
+  g_assert_cmpfloat_with_epsilon (x_value, 100.0, 0.001);
+
+  gtk_constraint_variable_unref (x);
+
+  g_object_unref (solver);
+}
+
+static void
+constraint_solver_eq_with_stay (void)
+{
+  GtkConstraintSolver *solver = gtk_constraint_solver_new ();
+
+  GtkConstraintVariable *x = gtk_constraint_solver_create_variable (solver, NULL, "x", 10.0);
+  GtkConstraintVariable *width = gtk_constraint_solver_create_variable (solver, NULL, "width", 10.0);
+  GtkConstraintVariable *right_min = gtk_constraint_solver_create_variable (solver, NULL, "rightMin", 100.0);
+
+  GtkConstraintExpressionBuilder builder;
+  gtk_constraint_expression_builder_init (&builder, solver);
+  gtk_constraint_expression_builder_term (&builder, x);
+  gtk_constraint_expression_builder_plus (&builder);
+  gtk_constraint_expression_builder_term (&builder, width);
+  GtkConstraintExpression *right = gtk_constraint_expression_builder_finish (&builder);
+
+  gtk_constraint_solver_add_stay_variable (solver, width, GTK_CONSTRAINT_STRENGTH_WEAK);
+  gtk_constraint_solver_add_stay_variable (solver, right_min, GTK_CONSTRAINT_STRENGTH_WEAK);
+  gtk_constraint_solver_add_constraint (solver,
+                                        right_min, GTK_CONSTRAINT_RELATION_EQ, right,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  double x_value = gtk_constraint_variable_get_value (x);
+  double width_value = gtk_constraint_variable_get_value (width);
+
+  g_assert_cmpfloat_with_epsilon (x_value, 90.0, 0.001);
+  g_assert_cmpfloat_with_epsilon (width_value, 10.0, 0.001);
+
+  gtk_constraint_variable_unref (right_min);
+  gtk_constraint_variable_unref (width);
+  gtk_constraint_variable_unref (x);
+
+  g_object_unref (solver);
+}
+
+static void
+constraint_solver_cassowary (void)
+{
+  GtkConstraintSolver *solver = gtk_constraint_solver_new ();
+
+  GtkConstraintVariable *x = gtk_constraint_solver_create_variable (solver, NULL, "x", 0.0);
+  GtkConstraintVariable *y = gtk_constraint_solver_create_variable (solver, NULL, "y", 0.0);
+
+  GtkConstraintExpression *e;
+
+  e = gtk_constraint_expression_new_from_variable (y);
+  gtk_constraint_solver_add_constraint (solver,
+                                        x, GTK_CONSTRAINT_RELATION_LE, e,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  e = gtk_constraint_expression_plus_constant (gtk_constraint_expression_new_from_variable (x), 3.0);
+  gtk_constraint_solver_add_constraint (solver,
+                                        y, GTK_CONSTRAINT_RELATION_EQ, e,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  e = gtk_constraint_expression_new (10.0);
+  gtk_constraint_solver_add_constraint (solver,
+                                        x, GTK_CONSTRAINT_RELATION_EQ, e,
+                                        GTK_CONSTRAINT_STRENGTH_WEAK);
+
+  e = gtk_constraint_expression_new (10.0);
+  gtk_constraint_solver_add_constraint (solver,
+                                        y, GTK_CONSTRAINT_RELATION_EQ, e,
+                                        GTK_CONSTRAINT_STRENGTH_WEAK);
+
+  double x_val = gtk_constraint_variable_get_value (x);
+  double y_val = gtk_constraint_variable_get_value (y);
+
+  g_test_message ("x = %g, y = %g", x_val, y_val);
+
+  /* The system is unstable and has two possible solutions we need to test */
+  g_assert_true ((G_APPROX_VALUE (x_val, 10.0, 1e-8) &&
+                  G_APPROX_VALUE (y_val, 13.0, 1e-8)) ||
+                 (G_APPROX_VALUE (x_val,  7.0, 1e-8) &&
+                  G_APPROX_VALUE (y_val, 10.0, 1e-8)));
+
+  gtk_constraint_variable_unref (x);
+  gtk_constraint_variable_unref (y);
+
+  g_object_unref (solver);
+}
+
+static void
+constraint_solver_edit_var_required (void)
+{
+  GtkConstraintSolver *solver = gtk_constraint_solver_new ();
+
+  GtkConstraintVariable *a = gtk_constraint_solver_create_variable (solver, NULL, "a", 0.0);
+  gtk_constraint_solver_add_stay_variable (solver, a, GTK_CONSTRAINT_STRENGTH_STRONG);
+
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (a), 0.0, 0.001);
+
+  gtk_constraint_solver_add_edit_variable (solver, a, GTK_CONSTRAINT_STRENGTH_REQUIRED);
+  gtk_constraint_solver_begin_edit (solver);
+  gtk_constraint_solver_suggest_value (solver, a, 2.0);
+  gtk_constraint_solver_resolve (solver);
+
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (a), 2.0, 0.001);
+
+  gtk_constraint_solver_suggest_value (solver, a, 10.0);
+  gtk_constraint_solver_resolve (solver);
+
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (a), 10.0, 0.001);
+
+  gtk_constraint_solver_end_edit (solver);
+
+  gtk_constraint_variable_unref (a);
+
+  g_object_unref (solver);
+}
+
+static void
+constraint_solver_edit_var_suggest (void)
+{
+  GtkConstraintSolver *solver = gtk_constraint_solver_new ();
+
+  GtkConstraintVariable *a = gtk_constraint_solver_create_variable (solver, NULL, "a", 0.0);
+  GtkConstraintVariable *b = gtk_constraint_solver_create_variable (solver, NULL, "b", 0.0);
+
+  gtk_constraint_solver_add_stay_variable (solver, a, GTK_CONSTRAINT_STRENGTH_STRONG);
+
+  GtkConstraintExpression *e = gtk_constraint_expression_new_from_variable (b);
+  gtk_constraint_solver_add_constraint (solver,
+                                        a, GTK_CONSTRAINT_RELATION_EQ, e,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  gtk_constraint_solver_resolve (solver);
+
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (a), 0.0, 0.001);
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (b), 0.0, 0.001);
+
+  gtk_constraint_solver_add_edit_variable (solver, a, GTK_CONSTRAINT_STRENGTH_REQUIRED);
+  gtk_constraint_solver_begin_edit (solver);
+
+  gtk_constraint_solver_suggest_value (solver, a, 2.0);
+  gtk_constraint_solver_resolve (solver);
+
+  g_test_message ("Check values after first edit");
+
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (a), 2.0, 0.001);
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (b), 2.0, 0.001);
+
+  gtk_constraint_solver_suggest_value (solver, a, 10.0);
+  gtk_constraint_solver_resolve (solver);
+
+  g_test_message ("Check values after second edit");
+
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (a), 10.0, 0.001);
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (b), 10.0, 0.001);
+
+  gtk_constraint_solver_suggest_value (solver, a, 12.0);
+  gtk_constraint_solver_resolve (solver);
+
+  g_test_message ("Check values after third edit");
+
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (a), 12.0, 0.001);
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (b), 12.0, 0.001);
+
+  gtk_constraint_variable_unref (a);
+  gtk_constraint_variable_unref (b);
+
+  g_object_unref (solver);
+}
+
+static void
+constraint_solver_paper (void)
+{
+  GtkConstraintSolver *solver = gtk_constraint_solver_new ();
+
+  GtkConstraintVariable *left = gtk_constraint_solver_create_variable (solver, NULL, "left", 0.0);
+  GtkConstraintVariable *middle = gtk_constraint_solver_create_variable (solver, NULL, "middle", 0.0);
+  GtkConstraintVariable *right = gtk_constraint_solver_create_variable (solver, NULL, "right", 0.0);
+
+  GtkConstraintExpressionBuilder builder;
+  GtkConstraintExpression *expr;
+
+  gtk_constraint_expression_builder_init (&builder, solver);
+  gtk_constraint_expression_builder_term (&builder, left);
+  gtk_constraint_expression_builder_plus (&builder);
+  gtk_constraint_expression_builder_term (&builder, right);
+  gtk_constraint_expression_builder_divide_by (&builder);
+  gtk_constraint_expression_builder_constant (&builder, 2.0);
+  expr = gtk_constraint_expression_builder_finish (&builder);
+  gtk_constraint_solver_add_constraint (solver,
+                                        middle, GTK_CONSTRAINT_RELATION_EQ, expr,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  gtk_constraint_expression_builder_init (&builder, solver);
+  gtk_constraint_expression_builder_term (&builder, left);
+  gtk_constraint_expression_builder_plus (&builder);
+  gtk_constraint_expression_builder_constant (&builder, 10.0);
+  expr = gtk_constraint_expression_builder_finish (&builder);
+  gtk_constraint_solver_add_constraint (solver,
+                                        right, GTK_CONSTRAINT_RELATION_EQ, expr,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  expr = gtk_constraint_expression_new (100.0);
+  gtk_constraint_solver_add_constraint (solver,
+                                        right, GTK_CONSTRAINT_RELATION_LE, expr,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  expr = gtk_constraint_expression_new (0.0);
+  gtk_constraint_solver_add_constraint (solver,
+                                        left, GTK_CONSTRAINT_RELATION_GE, expr,
+                                        GTK_CONSTRAINT_STRENGTH_REQUIRED);
+
+  g_test_message ("Check constraints hold");
+
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (middle),
+                                  (gtk_constraint_variable_get_value (left) + gtk_constraint_variable_get_value (right)) / 2.0,
+                                  0.001);
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (right),
+                                  gtk_constraint_variable_get_value (left) + 10.0,
+                                  0.001);
+  g_assert_cmpfloat (gtk_constraint_variable_get_value (right), <=, 100.0);
+  g_assert_cmpfloat (gtk_constraint_variable_get_value (left), >=, 0.0);
+
+  gtk_constraint_variable_set_value (middle, 45.0);
+  gtk_constraint_solver_add_stay_variable (solver, middle, GTK_CONSTRAINT_STRENGTH_WEAK);
+
+  g_test_message ("Check constraints hold after setting middle");
+
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (middle),
+                                  (gtk_constraint_variable_get_value (left) + gtk_constraint_variable_get_value (right)) / 2.0,
+                                  0.001);
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (right),
+                                  gtk_constraint_variable_get_value (left) + 10.0,
+                                  0.001);
+  g_assert_cmpfloat (gtk_constraint_variable_get_value (right), <=, 100.0);
+  g_assert_cmpfloat (gtk_constraint_variable_get_value (left), >=, 0.0);
+
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (left), 40.0, 0.001);
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (middle), 45.0, 0.001);
+  g_assert_cmpfloat_with_epsilon (gtk_constraint_variable_get_value (right), 50.0, 0.001);
+
+  gtk_constraint_variable_unref (left);
+  gtk_constraint_variable_unref (middle);
+  gtk_constraint_variable_unref (right);
+
+  g_object_unref (solver);
+}
+
+int
+main (int argc, char *argv[])
+{
+  g_test_init (&argc, &argv, NULL);
+  setlocale (LC_ALL, "C");
+
+  g_test_add_func ("/constraint-solver/paper", constraint_solver_paper);
+  g_test_add_func ("/constraint-solver/simple", constraint_solver_simple);
+  g_test_add_func ("/constraint-solver/constant/eq", constraint_solver_variable_eq_constant);
+  g_test_add_func ("/constraint-solver/constant/ge", constraint_solver_variable_geq_constant);
+  g_test_add_func ("/constraint-solver/constant/le", constraint_solver_variable_leq_constant);
+  g_test_add_func ("/constraint-solver/stay/simple", constraint_solver_stay);
+  g_test_add_func ("/constraint-solver/stay/eq", constraint_solver_eq_with_stay);
+  g_test_add_func ("/constraint-solver/cassowary", constraint_solver_cassowary);
+  g_test_add_func ("/constraint-solver/edit/required", constraint_solver_edit_var_required);
+  g_test_add_func ("/constraint-solver/edit/suggest", constraint_solver_edit_var_suggest);
+
+  return g_test_run ();
+}
@@ -300,6 +300,44 @@ test_submodel_add (void)
  g_object_unref (flat);
 }

+static void
+test_submodel_add2 (void)
+{
+  GtkFlattenListModel *flat;
+  GListStore *model, *store[2];
+
+  model = g_list_store_new (G_TYPE_LIST_MODEL);
+  flat = new_model (model);
+  assert_model (flat, "");
+  assert_changes (flat, "");
+
+  store[0] = add_store (model, 1, 0, 0);
+  store[1] = add_store (model, 1, 0, 0);
+  store[2] = add_store (model, 1, 0, 0);
+
+  assert_model (flat, "");
+  assert_changes (flat, "");
+
+  add (store[0], 1);
+  assert_model (flat, "1");
+  assert_changes (flat, "+0");
+
+  add (store[1], 3);
+  assert_model (flat, "1 3");
+  assert_changes (flat, "+1");
+
+  add (store[0], 2);
+  assert_model (flat, "1 2 3");
+  assert_changes (flat, "+1");
+
+  add (store[1], 4);
+  assert_model (flat, "1 2 3 4");
+  assert_changes (flat, "+3");
+
+  g_object_unref (model);
+  g_object_unref (flat);
+}
+
 static void
 test_model_remove (void)
 {
@@ -365,6 +403,7 @@ main (int argc, char *argv[])
  g_test_add_func ("/flattenlistmodel/model/add", test_model_add);
 #if GLIB_CHECK_VERSION (2, 58, 0) /* g_list_store_splice() is broken before 2.58 */
  g_test_add_func ("/flattenlistmodel/submodel/add", test_submodel_add);
+  g_test_add_func ("/flattenlistmodel/submodel/add2", test_submodel_add2);
  g_test_add_func ("/flattenlistmodel/model/remove", test_model_remove);
  g_test_add_func ("/flattenlistmodel/submodel/remove", test_submodel_remove);
 #endif
@@ -0,0 +1,681 @@
+/* Copyright (C) 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <gtk/gtk.h>
+
+#define GTK_TYPE_GIZMO                 (gtk_gizmo_get_type ())
+#define GTK_GIZMO(obj)                 (G_TYPE_CHECK_INSTANCE_CAST ((obj), GTK_TYPE_GIZMO, GtkGizmo))
+#define GTK_GIZMO_CLASS(klass)         (G_TYPE_CHECK_CLASS_CAST ((klass), GTK_TYPE_GIZMO, GtkGizmoClass))
+#define GTK_IS_GIZMO(obj)              (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GTK_TYPE_GIZMO))
+#define GTK_IS_GIZMO_CLASS(klass)      (G_TYPE_CHECK_CLASS_TYPE ((klass), GTK_TYPE_GIZMO))
+#define GTK_GIZMO_GET_CLASS(obj)       (G_TYPE_INSTANCE_GET_CLASS ((obj), GTK_TYPE_GIZMO, GtkGizmoClass))
+
+typedef struct _GtkGizmo GtkGizmo;
+
+struct _GtkGizmo {
+  GtkWidget parent;
+
+  const char *name;
+  int min_width;
+  int min_height;
+  int nat_width;
+  int nat_height;
+  int width;
+  int height;
+};
+
+typedef GtkWidgetClass GtkGizmoClass;
+
+G_DEFINE_TYPE (GtkGizmo, gtk_gizmo, GTK_TYPE_WIDGET);
+
+static void
+gtk_gizmo_measure (GtkWidget      *widget,
+                   GtkOrientation  orientation,
+                   int             for_size,
+                   int            *minimum,
+                   int            *natural,
+                   int            *minimum_baseline,
+                   int            *natural_baseline)
+{
+  GtkGizmo *self = GTK_GIZMO (widget);
+
+  if (orientation == GTK_ORIENTATION_HORIZONTAL)
+    {
+      *minimum = self->min_width;
+      *natural = self->nat_width;
+    }
+  else
+    {
+      *minimum = self->min_height;
+      *natural = self->nat_height;
+    }
+}
+
+static void
+gtk_gizmo_size_allocate (GtkWidget *widget,
+                         int        width,
+                         int        height,
+                         int        baseline)
+{
+  GtkGizmo *self = GTK_GIZMO (widget);
+
+  self->width = width;
+  self->height = height;
+}
+
+static void
+gtk_gizmo_class_init (GtkGizmoClass *klass)
+{
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  widget_class->measure = gtk_gizmo_measure;
+  widget_class->size_allocate = gtk_gizmo_size_allocate;
+}
+
+static void
+gtk_gizmo_init (GtkGizmo *self)
+{
+}
+
+/* Create a grid with three children in row
+ *
+ * +--------+--------+--------+
+ * | child1 | child2 | child3 |
+ * +--------+--------+--------+
+ *
+ * Verify that
+ * - the layout has the expected min and nat sizes
+ * - the children get their nat width when the layout does
+ * - they all get the same height
+ */
+static void
+test_simple_row (void)
+{
+  GtkWidget *window;
+  GtkWidget *parent;
+  GtkLayoutManager *layout;
+  GtkGizmo *child1;
+  GtkGizmo *child2;
+  GtkGizmo *child3;
+  GtkLayoutChild *lc;
+  int minimum, natural;
+
+  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  parent = g_object_new (GTK_TYPE_GIZMO, NULL);
+  gtk_container_add (GTK_CONTAINER (window), parent);
+
+  layout = gtk_grid_layout_new ();
+  gtk_widget_set_layout_manager (parent, layout);
+
+  child1 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child2 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child3 = g_object_new (GTK_TYPE_GIZMO, NULL);
+
+  child1->name = "child1";
+  child1->min_width = 10;
+  child1->min_height = 10;
+  child1->nat_width = 20;
+  child1->nat_height = 20;
+  child2->name = "child2";
+  child2->min_width = 20;
+  child2->min_height = 20;
+  child2->nat_width = 30;
+  child2->nat_height = 30;
+  child3->name = "child3";
+  child3->min_width = 30;
+  child3->min_height = 30;
+  child3->nat_width = 40;
+  child3->nat_height = 40;
+
+  gtk_widget_set_parent (GTK_WIDGET (child1), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child2), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child3), parent);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child1));
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child2));
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child3));
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 2);
+
+#if 0
+  gtk_widget_show (window);
+
+  g_timeout_add (1000, (GSourceFunc)gtk_main_quit, NULL);
+  gtk_main ();
+#endif
+
+  gtk_layout_manager_measure (layout,
+                              parent,
+                              GTK_ORIENTATION_HORIZONTAL,
+                              -1,
+                              &minimum,
+                              &natural,
+                              NULL,
+                              NULL);
+
+  g_assert_cmpint (minimum, ==, 10 + 20 + 30);
+  g_assert_cmpint (natural, ==, 20 + 30 + 40);
+
+  gtk_layout_manager_measure (layout,
+                              parent,
+                              GTK_ORIENTATION_VERTICAL,
+                              -1,
+                              &minimum,
+                              &natural,
+                              NULL,
+                              NULL);
+
+  g_assert_cmpint (minimum, ==, 30);
+  g_assert_cmpint (natural, ==, 40);
+
+  gtk_layout_manager_allocate (layout, parent, 90, 40, 0);
+
+  g_assert_cmpint (child1->width, ==, 20);
+  g_assert_cmpint (child2->width, ==, 30);
+  g_assert_cmpint (child3->width, ==, 40);
+
+  g_assert_cmpint (child1->height, ==, 40);
+  g_assert_cmpint (child2->height, ==, 40);
+  g_assert_cmpint (child3->height, ==, 40);
+
+  gtk_widget_unparent (GTK_WIDGET (child1));
+  gtk_widget_unparent (GTK_WIDGET (child2));
+  gtk_widget_unparent (GTK_WIDGET (child3));
+
+  gtk_widget_destroy (parent);
+}
+
+/* same as the previous test, with a column
+ */
+static void
+test_simple_column (void)
+{
+  GtkWidget *window;
+  GtkWidget *parent;
+  GtkLayoutManager *layout;
+  GtkGizmo *child1;
+  GtkGizmo *child2;
+  GtkGizmo *child3;
+  GtkLayoutChild *lc;
+  int minimum, natural;
+
+  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  parent = g_object_new (GTK_TYPE_GIZMO, NULL);
+  gtk_container_add (GTK_CONTAINER (window), parent);
+
+  layout = gtk_grid_layout_new ();
+  gtk_widget_set_layout_manager (parent, layout);
+
+  child1 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child2 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child3 = g_object_new (GTK_TYPE_GIZMO, NULL);
+
+  child1->name = "child1";
+  child1->min_width = 10;
+  child1->min_height = 10;
+  child1->nat_width = 20;
+  child1->nat_height = 20;
+  child2->name = "child2";
+  child2->min_width = 20;
+  child2->min_height = 20;
+  child2->nat_width = 30;
+  child2->nat_height = 30;
+  child3->name = "child3";
+  child3->min_width = 30;
+  child3->min_height = 30;
+  child3->nat_width = 40;
+  child3->nat_height = 40;
+
+  gtk_widget_set_parent (GTK_WIDGET (child1), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child2), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child3), parent);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child1));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child2));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child3));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 2);
+
+#if 0
+  gtk_widget_show (window);
+
+  g_timeout_add (1000, (GSourceFunc)gtk_main_quit, NULL);
+  gtk_main ();
+#endif
+
+  gtk_layout_manager_measure (layout,
+                              parent,
+                              GTK_ORIENTATION_HORIZONTAL,
+                              -1,
+                              &minimum,
+                              &natural,
+                              NULL,
+                              NULL);
+
+  g_assert_cmpint (minimum, ==, 30);
+  g_assert_cmpint (natural, ==, 40);
+
+  gtk_layout_manager_measure (layout,
+                              parent,
+                              GTK_ORIENTATION_VERTICAL,
+                              -1,
+                              &minimum,
+                              &natural,
+                              NULL,
+                              NULL);
+
+  g_assert_cmpint (minimum, ==, 10 + 20 + 30);
+  g_assert_cmpint (natural, ==, 20 + 30 + 40);
+
+  gtk_layout_manager_allocate (layout, parent, 40, 90, 0);
+
+  g_assert_cmpint (child1->width, ==, 40);
+  g_assert_cmpint (child2->width, ==, 40);
+  g_assert_cmpint (child3->width, ==, 40);
+
+  g_assert_cmpint (child1->height, ==, 20);
+  g_assert_cmpint (child2->height, ==, 30);
+  g_assert_cmpint (child3->height, ==, 40);
+
+  gtk_widget_unparent (GTK_WIDGET (child1));
+  gtk_widget_unparent (GTK_WIDGET (child2));
+  gtk_widget_unparent (GTK_WIDGET (child3));
+
+  gtk_widget_destroy (parent);
+}
+
+/* Create a grid with spanning children
+ *
+ * +--------+-----------------+
+ * | child1 |      child2     |
+ * +--------+--------+--------+
+ * |      child3     | child4 |
+ * +-----------------+--------+
+ *
+ * Verify that
+ * - the layout has the expected min and nat sizes
+ * - the children get their nat width when the layout does
+ */
+static void
+test_spans (void)
+{
+  GtkWidget *window;
+  GtkWidget *parent;
+  GtkLayoutManager *layout;
+  GtkGizmo *child1;
+  GtkGizmo *child2;
+  GtkGizmo *child3;
+  GtkGizmo *child4;
+  GtkLayoutChild *lc;
+  int minimum, natural;
+
+  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  parent = g_object_new (GTK_TYPE_GIZMO, NULL);
+  gtk_container_add (GTK_CONTAINER (window), parent);
+
+  layout = gtk_grid_layout_new ();
+  gtk_widget_set_layout_manager (parent, layout);
+
+  child1 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child2 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child3 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child4 = g_object_new (GTK_TYPE_GIZMO, NULL);
+
+  child1->name = "child1";
+  child1->min_width = 10;
+  child1->min_height = 10;
+  child1->nat_width = 20;
+  child1->nat_height = 20;
+  child2->name = "child2";
+  child2->min_width = 20;
+  child2->min_height = 20;
+  child2->nat_width = 30;
+  child2->nat_height = 30;
+  child3->name = "child3";
+  child3->min_width = 30;
+  child3->min_height = 30;
+  child3->nat_width = 40;
+  child3->nat_height = 40;
+  child4->name = "child4";
+  child4->min_width = 30;
+  child4->min_height = 30;
+  child4->nat_width = 40;
+  child4->nat_height = 40;
+
+  gtk_widget_set_parent (GTK_WIDGET (child1), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child2), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child3), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child4), parent);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child1));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child2));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+  gtk_grid_layout_child_set_column_span (GTK_GRID_LAYOUT_CHILD (lc), 2);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child3));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+  gtk_grid_layout_child_set_column_span (GTK_GRID_LAYOUT_CHILD (lc), 2);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child4));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 2);
+
+#if 0
+  gtk_widget_show (window);
+
+  g_timeout_add (1000, (GSourceFunc)gtk_main_quit, NULL);
+  gtk_main ();
+#endif
+
+  gtk_layout_manager_measure (layout,
+                              parent,
+                              GTK_ORIENTATION_HORIZONTAL,
+                              -1,
+                              &minimum,
+                              &natural,
+                              NULL,
+                              NULL);
+
+  g_assert_cmpint (minimum, ==, 60);
+  g_assert_cmpint (natural, ==, 80);
+
+  gtk_layout_manager_measure (layout,
+                              parent,
+                              GTK_ORIENTATION_VERTICAL,
+                              -1,
+                              &minimum,
+                              &natural,
+                              NULL,
+                              NULL);
+
+  g_assert_cmpint (minimum, ==, 50);
+  g_assert_cmpint (natural, ==, 70);
+
+  gtk_layout_manager_allocate (layout, parent, 80, 70, 0);
+
+  g_assert_cmpint (child1->width, ==, 30);
+  g_assert_cmpint (child2->width, ==, 50);
+  g_assert_cmpint (child3->width, ==, 40);
+  g_assert_cmpint (child4->width, ==, 40);
+
+  g_assert_cmpint (child1->height, ==, 30);
+  g_assert_cmpint (child2->height, ==, 30);
+  g_assert_cmpint (child3->height, ==, 40);
+  g_assert_cmpint (child4->height, ==, 40);
+
+  gtk_widget_unparent (GTK_WIDGET (child1));
+  gtk_widget_unparent (GTK_WIDGET (child2));
+  gtk_widget_unparent (GTK_WIDGET (child3));
+  gtk_widget_unparent (GTK_WIDGET (child4));
+
+  gtk_widget_destroy (parent);
+}
+
+/* Create a 2x2 homogeneous grid and verify
+ * all children get the same size.
+ */
+static void
+test_homogeneous (void)
+{
+  GtkWidget *window;
+  GtkWidget *parent;
+  GtkLayoutManager *layout;
+  GtkGizmo *child1;
+  GtkGizmo *child2;
+  GtkGizmo *child3;
+  GtkGizmo *child4;
+  GtkLayoutChild *lc;
+  int minimum, natural;
+
+  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  parent = g_object_new (GTK_TYPE_GIZMO, NULL);
+  gtk_container_add (GTK_CONTAINER (window), parent);
+
+  layout = gtk_grid_layout_new ();
+  gtk_grid_layout_set_row_homogeneous (GTK_GRID_LAYOUT (layout), TRUE);
+  gtk_grid_layout_set_column_homogeneous (GTK_GRID_LAYOUT (layout), TRUE);
+  gtk_widget_set_layout_manager (parent, layout);
+
+  child1 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child2 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child3 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child4 = g_object_new (GTK_TYPE_GIZMO, NULL);
+
+  child1->name = "child1";
+  child1->min_width = 10;
+  child1->min_height = 10;
+  child1->nat_width = 20;
+  child1->nat_height = 20;
+  child2->name = "child2";
+  child2->min_width = 20;
+  child2->min_height = 20;
+  child2->nat_width = 30;
+  child2->nat_height = 30;
+  child3->name = "child3";
+  child3->min_width = 30;
+  child3->min_height = 30;
+  child3->nat_width = 40;
+  child3->nat_height = 40;
+  child4->name = "child4";
+  child4->min_width = 30;
+  child4->min_height = 30;
+  child4->nat_width = 40;
+  child4->nat_height = 40;
+
+  gtk_widget_set_parent (GTK_WIDGET (child1), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child2), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child3), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child4), parent);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child1));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child2));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child3));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child4));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+
+#if 0
+  gtk_widget_show (window);
+
+  g_timeout_add (1000, (GSourceFunc)gtk_main_quit, NULL);
+  gtk_main ();
+#endif
+
+  gtk_layout_manager_measure (layout,
+                              parent,
+                              GTK_ORIENTATION_HORIZONTAL,
+                              -1,
+                              &minimum,
+                              &natural,
+                              NULL,
+                              NULL);
+
+  g_assert_cmpint (minimum, ==, 60);
+  g_assert_cmpint (natural, ==, 80);
+
+  gtk_layout_manager_measure (layout,
+                              parent,
+                              GTK_ORIENTATION_VERTICAL,
+                              -1,
+                              &minimum,
+                              &natural,
+                              NULL,
+                              NULL);
+
+  g_assert_cmpint (minimum, ==, 60);
+  g_assert_cmpint (natural, ==, 80);
+
+  gtk_layout_manager_allocate (layout, parent, 80, 80, 0);
+
+  g_assert_cmpint (child1->width, ==, 40);
+  g_assert_cmpint (child2->width, ==, 40);
+  g_assert_cmpint (child3->width, ==, 40);
+  g_assert_cmpint (child4->width, ==, 40);
+
+  g_assert_cmpint (child1->height, ==, 40);
+  g_assert_cmpint (child2->height, ==, 40);
+  g_assert_cmpint (child3->height, ==, 40);
+  g_assert_cmpint (child4->height, ==, 40);
+
+  gtk_widget_unparent (GTK_WIDGET (child1));
+  gtk_widget_unparent (GTK_WIDGET (child2));
+  gtk_widget_unparent (GTK_WIDGET (child3));
+  gtk_widget_unparent (GTK_WIDGET (child4));
+
+  gtk_widget_destroy (parent);
+}
+
+/* Create a layout with three children
+ *
+ * +--------+--------+
+ * | child1 | child2 |
+ * +--------+--------+
+ * |      child3     |
+ * +-----------------+
+ *
+ * This is a layout that we also reproduce with
+ * constraints, for comparison. Among the contraints:
+ * - child1.width == child2.width
+ * - child1.height == child2.height == child3.height
+ */
+static void
+test_simple_layout (void)
+{
+  GtkWidget *window;
+  GtkWidget *parent;
+  GtkLayoutManager *layout;
+  GtkLayoutChild *lc;
+  GtkGizmo *child1;
+  GtkGizmo *child2;
+  GtkGizmo *child3;
+  int minimum, natural;
+
+  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  parent = g_object_new (GTK_TYPE_GIZMO, NULL);
+  gtk_container_add (GTK_CONTAINER (window), parent);
+
+  layout = gtk_grid_layout_new ();
+  gtk_grid_layout_set_row_homogeneous (GTK_GRID_LAYOUT (layout), TRUE);
+  gtk_grid_layout_set_column_homogeneous (GTK_GRID_LAYOUT (layout), TRUE);
+  gtk_widget_set_layout_manager (parent, layout);
+
+  child1 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child2 = g_object_new (GTK_TYPE_GIZMO, NULL);
+  child3 = g_object_new (GTK_TYPE_GIZMO, NULL);
+
+  child1->name = "child1";
+  child1->min_width = 10;
+  child1->min_height = 10;
+  child1->nat_width = 50;
+  child1->nat_height = 50;
+  child2->name = "child2";
+  child2->min_width = 20;
+  child2->min_height = 20;
+  child2->nat_width = 50;
+  child2->nat_height = 50;
+  child3->name = "child3";
+  child3->min_width = 50;
+  child3->min_height = 10;
+  child3->nat_width = 50;
+  child3->nat_height = 50;
+
+  gtk_widget_set_parent (GTK_WIDGET (child1), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child2), parent);
+  gtk_widget_set_parent (GTK_WIDGET (child3), parent);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child1));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child2));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+
+  lc = gtk_layout_manager_get_layout_child (layout, GTK_WIDGET (child3));
+  gtk_grid_layout_child_set_top_attach (GTK_GRID_LAYOUT_CHILD (lc), 1);
+  gtk_grid_layout_child_set_left_attach (GTK_GRID_LAYOUT_CHILD (lc), 0);
+  gtk_grid_layout_child_set_column_span (GTK_GRID_LAYOUT_CHILD (lc), 2);
+
+  gtk_layout_manager_measure (layout,
+                              parent,
+                              GTK_ORIENTATION_HORIZONTAL,
+                              -1,
+                              &minimum,
+                              &natural,
+                              NULL,
+                              NULL);
+
+  g_assert_cmpint (minimum, ==, 50);
+  g_assert_cmpint (natural, ==, 100);
+
+  gtk_layout_manager_measure (layout,
+                              parent,
+                              GTK_ORIENTATION_VERTICAL,
+                              -1,
+                              &minimum,
+                              &natural,
+                              NULL,
+                              NULL);
+
+  g_assert_cmpint (minimum, ==, 40);
+  g_assert_cmpint (natural, ==, 100);
+
+  gtk_layout_manager_allocate (layout, parent, 100, 100, 0);
+
+  g_assert_cmpint (child1->width, ==, 50);
+  g_assert_cmpint (child2->width, ==, 50);
+  g_assert_cmpint (child3->width, ==, 100);
+
+  g_assert_cmpint (child1->height, ==, 50);
+  g_assert_cmpint (child2->height, ==, 50);
+  g_assert_cmpint (child3->height, ==, 50);
+
+  gtk_widget_unparent (GTK_WIDGET (child1));
+  gtk_widget_unparent (GTK_WIDGET (child2));
+  gtk_widget_unparent (GTK_WIDGET (child3));
+
+  gtk_widget_destroy (parent);
+}
+
+int
+main (int   argc,
+      char *argv[])
+{
+  gtk_test_init (&argc, &argv);
+
+  g_test_add_func ("/grid-layout/row", test_simple_row);
+  g_test_add_func ("/grid-layout/column", test_simple_column);
+  g_test_add_func ("/grid-layout/span", test_spans);
+  g_test_add_func ("/grid-layout/homogeneous", test_homogeneous);
+  g_test_add_func ("/grid-layout/simple", test_simple_layout);
+
+  return g_test_run();
+}
@@ -17,6 +17,11 @@ tests = [
  ['builderparser'],
  ['cellarea'],
  ['check-icon-names'],
+  ['constraint-solver', [
+      '../../gtk/gtkconstraintsolver.c',
+      '../../gtk/gtkconstraintexpression.c',
+    ], ['-DGTK_COMPILATION', '-UG_ENABLE_DEBUG']
+  ],
  ['cssprovider'],
  ['rbtree-crash', ['../../gtk/gtkrbtree.c'], ['-DGTK_COMPILATION', '-UG_ENABLE_DEBUG']],
  ['defaultvalue'],
@@ -28,6 +33,7 @@ tests = [
  ['focus'],
  ['gestures'],
  ['grid'],
+  ['grid-layout'],
  ['gtkmenu'],
  ['icontheme'],
  ['keyhash', ['../../gtk/gtkkeyhash.c', gtkresources, '../../gtk/gtkprivate.c'], gtk_cargs],