[libadwaita/wip/exalm/pref-window-toast] demo: Add a prefrences window toast demo

[Alexander Mikhaylenko <alexm src gnome org>]

commit 70de5ed9afdcbd755b687a02a047ea63e693de62
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Thu Nov 11 20:20:42 2021 +0500

    demo: Add a prefrences window toast demo

 demo/adw-demo-preferences-window.c  |  8 ++++++++
 demo/adw-demo-preferences-window.ui | 17 +++++++++++++++++
 2 files changed, 25 insertions(+)
---
diff --git a/demo/adw-demo-preferences-window.c b/demo/adw-demo-preferences-window.c
index bd9d2a42..7d219d0a 100644
--- a/demo/adw-demo-preferences-window.c
+++ b/demo/adw-demo-preferences-window.c
@@ -34,6 +34,12 @@ subpage2_activated_cb (AdwDemoPreferencesWindow *self)
   adw_preferences_window_present_subpage (ADW_PREFERENCES_WINDOW (self), self->subpage2);
 }
 
+static void
+toast_show_cb (AdwPreferencesWindow *window)
+{
+  adw_preferences_window_add_toast (window, adw_toast_new ("Example toast"));
+}
+
 static void
 adw_demo_preferences_window_class_init (AdwDemoPreferencesWindowClass *klass)
 {
@@ -47,6 +53,8 @@ adw_demo_preferences_window_class_init (AdwDemoPreferencesWindowClass *klass)
   gtk_widget_class_bind_template_callback (widget_class, return_to_preferences_cb);
   gtk_widget_class_bind_template_callback (widget_class, subpage1_activated_cb);
   gtk_widget_class_bind_template_callback (widget_class, subpage2_activated_cb);
+
+  gtk_widget_class_install_action (widget_class, "toast.show", NULL, (GtkWidgetActionActivateFunc) 
toast_show_cb);
 }
 
 static void
diff --git a/demo/adw-demo-preferences-window.ui b/demo/adw-demo-preferences-window.ui
index d4beef59..a270fe0d 100644
--- a/demo/adw-demo-preferences-window.ui
+++ b/demo/adw-demo-preferences-window.ui
@@ -81,6 +81,23 @@
             </child>
           </object>
         </child>
+        <child>
+          <object class="AdwPreferencesGroup">
+            <property name="title" translatable="yes">Toasts</property>
+            <child>
+              <object class="AdwActionRow">
+                <property name="title" translatable="yes">Show a toast</property>
+                <child>
+                  <object class="GtkButton">
+                    <property name="label" translatable="yes">Show</property>
+                    <property name="action-name">toast.show</property>
+                    <property name="valign">center</property>
+                  </object>
+                </child>
+              </object>
+            </child>
+          </object>
+        </child>
         <child>
           <object class="AdwPreferencesGroup">
             <property name="description" translatable="yes">Preferences windows can have subpages.</property>