Refresh the tutorial examples

Redo this series of examples from 2013, and adapt it to modern
way of doing things. The biggest differences are that we use
a headerbar right from the start, and don't mention the app
menu.

Fixes: #2730

examples/application6/exampleapp.c

@@ -46,8 +46,6 @@ static GActionEntry app_entries[] =
 static void
 example_app_startup (GApplication *app)
 {
-  GtkBuilder *builder;
-  GMenuModel *app_menu;
   const gchar *quit_accels[2] = { "<Ctrl>Q", NULL };
 
   G_APPLICATION_CLASS (example_app_parent_class)->startup (app);
@@ -58,11 +56,6 @@ example_app_startup (GApplication *app)
   gtk_application_set_accels_for_action (GTK_APPLICATION (app),
                                          "app.quit",
                                          quit_accels);
-
-  builder = gtk_builder_new_from_resource ("/org/gtk/exampleapp/app-menu.ui");
-  app_menu = G_MENU_MODEL (gtk_builder_get_object (builder, "appmenu"));
-  gtk_application_set_app_menu (GTK_APPLICATION (app), app_menu);
-  g_object_unref (builder);
 }
 
 static void

examples/application6/exampleapp.gresource.xml

@@ -2,7 +2,7 @@
 <gresources>
   <gresource prefix="/org/gtk/exampleapp">
     <file preprocess="xml-stripblanks">window.ui</file>
-    <file preprocess="xml-stripblanks">app-menu.ui</file>
+    <file preprocess="xml-stripblanks">gears-menu.ui</file>
     <file preprocess="xml-stripblanks">prefs.ui</file>
   </gresource>
 </gresources>

examples/application6/exampleappwin.c

@@ -9,6 +9,7 @@ struct _ExampleAppWindow
 
   GSettings *settings;
   GtkWidget *stack;
+  GtkWidget *gears;
 };
 
 G_DEFINE_TYPE (ExampleAppWindow, example_app_window, GTK_TYPE_APPLICATION_WINDOW)
@@ -16,7 +17,16 @@ G_DEFINE_TYPE (ExampleAppWindow, example_app_window, GTK_TYPE_APPLICATION_WINDOW
 static void
 example_app_window_init (ExampleAppWindow *win)
 {
+  GtkBuilder *builder;
+  GMenuModel *menu;
+
   gtk_widget_init_template (GTK_WIDGET (win));
+
+  builder = gtk_builder_new_from_resource ("/org/gtk/exampleapp/gears-menu.ui");
+  menu = G_MENU_MODEL (gtk_builder_get_object (builder, "menu"));
+  gtk_menu_button_set_menu_model (GTK_MENU_BUTTON (win->gears), menu);
+  g_object_unref (builder);
+
   win->settings = g_settings_new ("org.gtk.exampleapp");
 
   g_settings_bind (win->settings, "transition",
@@ -44,6 +54,7 @@ example_app_window_class_init (ExampleAppWindowClass *class)
   gtk_widget_class_set_template_from_resource (GTK_WIDGET_CLASS (class),
                                                "/org/gtk/exampleapp/window.ui");
   gtk_widget_class_bind_template_child (GTK_WIDGET_CLASS (class), ExampleAppWindow, stack);
+  gtk_widget_class_bind_template_child (GTK_WIDGET_CLASS (class), ExampleAppWindow, gears);
 }
 
 ExampleAppWindow *

examples/application6/gears-menu.ui

@@ -1,5 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <menu id="appmenu">
+  <menu id="menu">
     <section>
       <item>
         <attribute name="label" translatable="yes">_Preferences</attribute>

examples/application6/prefs.ui

@@ -4,16 +4,16 @@
     <property name="title" translatable="yes">Preferences</property>
     <property name="resizable">0</property>
     <property name="modal">1</property>
-    <child internal-child="vbox">
-      <object class="GtkBox" id="vbox">
+    <child internal-child="content_area">
+      <object class="GtkBox" id="content_area">
         <child>
           <object class="GtkGrid" id="grid">
-            <property name="margin-start">6</property>
-            <property name="margin-end">6</property>
-            <property name="margin-top">6</property>
-            <property name="margin-bottom">6</property>
+            <property name="margin-start">12</property>
+            <property name="margin-end">12</property>
+            <property name="margin-top">12</property>
+            <property name="margin-bottom">12</property>
             <property name="row-spacing">12</property>
-            <property name="column-spacing">6</property>
+            <property name="column-spacing">12</property>
             <child>
               <object class="GtkLabel" id="fontlabel">
                 <property name="label">_Font:</property>

examples/application6/window.ui

@@ -1,20 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
 <interface>
   <template class="ExampleAppWindow" parent="GtkApplicationWindow">
     <property name="title" translatable="yes">Example Application</property>
     <property name="default-width">600</property>
     <property name="default-height">400</property>
+    <child type="titlebar">
+      <object class="GtkHeaderBar" id="header">
+        <property name="show-title-buttons">1</property>
+        <child type="title">
+          <object class="GtkStackSwitcher" id="tabs">
+            <property name="stack">stack</property>
+          </object>
+        </child>
+        <child type="end">
+          <object class="GtkMenuButton" id="gears">
+            <property name="direction">none</property>
+          </object>
+        </child>
+      </object>
+    </child>
     <child>
       <object class="GtkBox" id="content_box">
         <property name="orientation">vertical</property>
-        <child>
-          <object class="GtkHeaderBar" id="header">
-            <child type="title">
-              <object class="GtkStackSwitcher" id="tabs">
-                <property name="stack">stack</property>
-              </object>
-            </child>
-          </object>
-        </child>
         <child>
           <object class="GtkStack" id="stack"/>
         </child>