example: Bind back and close buttons visibility to fold

Directly bind whether the back button and the close button are visible
to whether the headerbar is folded.

examples/example-window.c

@@ -38,23 +38,6 @@ example_window_key_pressed_cb (GtkWidget     *sender,
   return FALSE;
 }
 
-static void
-update (ExampleWindow *self)
-{
-  HdyFold fold = hdy_leaflet_get_fold (self->content_box);
-
-  gtk_header_bar_set_show_close_button (self->header_bar, fold == HDY_FOLD_FOLDED);
-  gtk_widget_set_visible (GTK_WIDGET (self->back), fold == HDY_FOLD_FOLDED);
-}
-
-static void
-example_window_notify_fold_cb (GObject       *sender,
-                                 GParamSpec    *pspec,
-                                 ExampleWindow *self)
-{
-  update (self);
-}
-
 static void
 example_window_notify_visible_child_cb (GObject       *sender,
                                         GParamSpec    *pspec,
@@ -248,7 +231,6 @@ example_window_class_init (ExampleWindowClass *klass)
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, adj_arrows_count);
   gtk_widget_class_bind_template_child (widget_class, ExampleWindow, adj_arrows_duration);
   gtk_widget_class_bind_template_callback_full (widget_class, "key_pressed_cb", G_CALLBACK(example_window_key_pressed_cb));
-  gtk_widget_class_bind_template_callback_full (widget_class, "notify_fold_cb", G_CALLBACK(example_window_notify_fold_cb));
   gtk_widget_class_bind_template_callback_full (widget_class, "notify_visible_child_cb", G_CALLBACK(example_window_notify_visible_child_cb));
   gtk_widget_class_bind_template_callback_full (widget_class, "back_clicked_cb", G_CALLBACK(example_window_back_clicked_cb));
   gtk_widget_class_bind_template_callback_full (widget_class, "submitted_cb", G_CALLBACK(example_window_submitted_cb));
@@ -268,6 +250,4 @@ example_window_init (ExampleWindow *self)
   gtk_widget_init_template (GTK_WIDGET (self));
 
   hdy_leaflet_set_visible_child (self->content_box, GTK_WIDGET (self->stack));
-
-  update (self);
 }

examples/example-window.ui

@@ -38,6 +38,7 @@
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
                 <property name="title">Handy Widget Factory</property>
+                <property name="show_close_button" bind-source="header_box" bind-property="folded" bind-flags="sync-create"/>
               </object>
               <packing>
                 <property name="name">sidebar</property>
@@ -64,6 +65,7 @@
                     <property name="receives_default">False</property>
                     <property name="valign">center</property>
                     <property name="use-underline">True</property>
+                    <property name="visible" bind-source="header_box" bind-property="folded" bind-flags="sync-create"/>
                     <signal name="clicked" handler="back_clicked_cb"/>
                     <style>
                       <class name="image-button"/>
@@ -98,7 +100,6 @@
         <property name="can_focus">False</property>
         <property name="mode_transition_type">slide</property>
         <property name="child_transition_type">slide</property>
-        <signal name="notify::fold" handler="notify_fold_cb" after="yes" swapped="no"/>
         <child>
           <object class="GtkStackSidebar" id="sidebar">
             <property name="width_request">270</property>