selection: Make the model an interface property

This is in line with what we do for other wrapper models.

gtk/gtkmultiselection.c

@@ -53,9 +53,11 @@ struct _GtkMultiSelectionClass
 
 enum {
   PROP_0,
+
+  /* selectionmodel */
   PROP_MODEL,
 
-  N_PROPS,
+  N_PROPS = PROP_MODEL
 };
 
 static GParamSpec *properties[N_PROPS] = { NULL, };
@@ -287,19 +289,7 @@ gtk_multi_selection_class_init (GtkMultiSelectionClass *klass)
   gobject_class->set_property = gtk_multi_selection_set_property;
   gobject_class->dispose = gtk_multi_selection_dispose;
 
-  /**
-   * GtkMultiSelection:model
-   *
-   * The list managed by this selection
-   */
-  properties[PROP_MODEL] =
-    g_param_spec_object ("model",
-                         P_("Model"),
-                         P_("List managed by this selection"),
-                         G_TYPE_LIST_MODEL,
-                         G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
-
-  g_object_class_install_properties (gobject_class, N_PROPS, properties);
+  g_object_class_override_property (gobject_class, PROP_MODEL, "model");
 }
 
 static void

gtk/gtknoselection.c

@@ -48,9 +48,11 @@ struct _GtkNoSelectionClass
 
 enum {
   PROP_0,
+
+  /* selectionmodel */
   PROP_MODEL,
 
-  N_PROPS,
+  N_PROPS = PROP_MODEL
 };
 
 static GParamSpec *properties[N_PROPS] = { NULL, };
@@ -177,19 +179,7 @@ gtk_no_selection_class_init (GtkNoSelectionClass *klass)
   gobject_class->set_property = gtk_no_selection_set_property;
   gobject_class->dispose = gtk_no_selection_dispose;
 
-  /**
-   * GtkNoSelection:model
-   *
-   * The list managed by this selection
-   */
-  properties[PROP_MODEL] =
-    g_param_spec_object ("model",
-                         P_("Model"),
-                         P_("List managed by this selection"),
-                         G_TYPE_LIST_MODEL,
-                         G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
-
-  g_object_class_install_properties (gobject_class, N_PROPS, properties);
+  g_object_class_override_property (gobject_class, PROP_MODEL, "model");
 }
 
 static void

gtk/gtkselectionmodel.c

@@ -21,6 +21,7 @@
 
 #include "gtkselectionmodel.h"
 
+#include "gtkintl.h"
 #include "gtkmarshalers.h"
 
 /**
@@ -156,6 +157,17 @@ gtk_selection_model_default_init (GtkSelectionModelInterface *iface)
   g_signal_set_va_marshaller (signals[SELECTION_CHANGED],
                               GTK_TYPE_SELECTION_MODEL,
                               _gtk_marshal_VOID__UINT_UINTv);
+
+  g_object_interface_install_property (iface,
+    g_param_spec_object ("model",
+                         P_("Model"),
+                         P_("List managed by this selection"),
+                         G_TYPE_LIST_MODEL,
+                         G_PARAM_READWRITE
+                         | G_PARAM_CONSTRUCT_ONLY
+                         | G_PARAM_EXPLICIT_NOTIFY
+                         | G_PARAM_STATIC_STRINGS));
+
 }
 
 /**
@@ -254,6 +266,18 @@ gtk_selection_model_unselect_all (GtkSelectionModel *model)
   return iface->unselect_all (model);
 }
 
+GListModel *
+gtk_selection_model_get_model (GtkSelectionModel *model)
+{
+  GListModel *child;
+
+  g_object_get (model, "model", &child, NULL);
+  if (child)
+    g_object_unref (child);
+
+  return child;
+}
+
 void
 gtk_selection_model_selection_changed (GtkSelectionModel *model,
                                        guint              position,

gtk/gtkselectionmodel.h

@@ -108,6 +108,9 @@ gboolean                gtk_selection_model_select_all          (GtkSelectionMod
 GDK_AVAILABLE_IN_ALL
 gboolean                gtk_selection_model_unselect_all        (GtkSelectionModel      *model);
 
+GDK_AVAILABLE_IN_ALL
+GListModel *            gtk_selection_model_get_model           (GtkSelectionModel      *model);
+
 /* for implementations only */
 GDK_AVAILABLE_IN_ALL
 void                    gtk_selection_model_selection_changed   (GtkSelectionModel      *model,

gtk/gtksingleselection.c

@@ -55,10 +55,11 @@ enum {
   PROP_0,
   PROP_AUTOSELECT,
   PROP_CAN_UNSELECT,
-  PROP_MODEL,
   PROP_SELECTED,
 
-  N_PROPS,
+  /* selectionmodel */
+  PROP_MODEL,
+  N_PROPS = PROP_MODEL
 };
 
 static GParamSpec *properties[N_PROPS] = { NULL, };
@@ -337,6 +338,8 @@ gtk_single_selection_class_init (GtkSingleSelectionClass *klass)
   gobject_class->set_property = gtk_single_selection_set_property;
   gobject_class->dispose = gtk_single_selection_dispose;
 
+  g_object_class_override_property (gobject_class, PROP_MODEL, "model");
+
   /**
    * GtkSingleSelection:autoselect
    *
@@ -361,18 +364,6 @@ gtk_single_selection_class_init (GtkSingleSelectionClass *klass)
                           FALSE,
                           G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
 
-  /**
-   * GtkSingleSelection:model
-   *
-   * The list managed by this selection
-   */
-  properties[PROP_MODEL] =
-    g_param_spec_object ("model",
-                         P_("Model"),
-                         P_("List managed by this selection"),
-                         G_TYPE_LIST_MODEL,
-                         G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
-
   /**
    * GtkSingleSelection:selected
    *