shell: Allow panels to register custom widgets in the shell header

This allows us to add the kill switch in the various different panels to match
the mockups, and also allows us to connect up any custom functionality the
designers want.

For example, in the bluetooth panel we might want to allow the GtkLabel to be
edited to change the bluetooth device name.

shell/cc-shell.c

@@ -236,3 +236,24 @@ cc_shell_get_toplevel (CcShell *shell)
   return NULL;
 }
 
+void
+cc_shell_embed_widget_in_header (CcShell *shell, GtkWidget *widget)
+{
+  CcShellClass *class;
+
+  g_return_if_fail (CC_IS_SHELL (shell));
+
+  class = (CcShellClass *) G_OBJECT_GET_CLASS (shell);
+
+  if (!class->embed_widget_in_header)
+    {
+      g_warning ("Object of type \"%s\" does not implement required virtual"
+                 " function \"embed_widget_in_header\",",
+                 G_OBJECT_TYPE_NAME (shell));
+      return FALSE;
+    }
+  else
+    {
+      return class->embed_widget_in_header (shell, widget);
+    }
+}

shell/cc-shell.h

@@ -89,6 +89,8 @@ struct _CcShellClass
                                            const gchar **argv,
                                            GError      **error);
   GtkWidget * (*get_toplevel)             (CcShell      *shell);
+  void        (*embed_widget_in_header)   (CcShell      *shell,
+                                           GtkWidget    *widget);
 };
 
 GType           cc_shell_get_type                 (void) G_GNUC_CONST;
@@ -102,6 +104,9 @@ gboolean        cc_shell_set_active_panel_from_id (CcShell      *shell,
                                                    GError      **error);
 GtkWidget *     cc_shell_get_toplevel             (CcShell      *shell);
 
+void            cc_shell_embed_widget_in_header   (CcShell      *shell,
+                                                   GtkWidget    *widget);
+
 G_END_DECLS
 
 #endif /* _CC_SHELL_H */

shell/gnome-control-center.c

@@ -69,6 +69,7 @@ struct _GnomeControlCenterPrivate
   GtkWidget  *window;
   GtkWidget  *search_entry;
   GtkWidget  *lock_button;
+  GPtrArray  *custom_widgets;
 
   GMenuTree  *menu_tree;
   GtkListStore *store;
@@ -200,6 +201,23 @@ activate_panel (GnomeControlCenter *shell,
     }
 }
 
+static void
+_shell_remove_all_custom_widgets (GnomeControlCenterPrivate *priv)
+{
+  GtkBox *box;
+  GtkWidget *widget;
+  guint i;
+
+  /* remove from the header */
+  box = GTK_BOX (W (priv->builder, "topright"));
+  for (i = 0; i < priv->custom_widgets->len; i++)
+    {
+        widget = g_ptr_array_index (priv->custom_widgets, i);
+        gtk_container_remove (GTK_CONTAINER (box), widget);
+    }
+  g_ptr_array_set_size (priv->custom_widgets, 0);
+}
+
 static void
 shell_show_overview_page (GnomeControlCenterPrivate *priv)
 {
@@ -220,6 +238,9 @@ shell_show_overview_page (GnomeControlCenterPrivate *priv)
   gtk_window_set_default_icon_name (priv->default_window_icon);
   gtk_window_set_icon_name (GTK_WINDOW (priv->window),
                             priv->default_window_icon);
+
+  /* clear any custom widgets */
+  _shell_remove_all_custom_widgets (priv);
 }
 
 void
@@ -809,6 +830,20 @@ notebook_switch_page_cb (GtkNotebook               *book,
     }
 }
 
+/* CcShell implementation */
+static void
+_shell_embed_widget_in_header (CcShell      *shell,
+                               GtkWidget    *widget)
+{
+  GnomeControlCenterPrivate *priv = GNOME_CONTROL_CENTER (shell)->priv;
+  GtkBox *box;
+
+  /* add to header */
+  box = GTK_BOX (W (priv->builder, "topright"));
+  gtk_box_pack_end (box, widget, FALSE, FALSE, 0);
+  g_ptr_array_add (priv->custom_widgets, g_object_ref (widget));
+}
+
 /* CcShell implementation */
 static gboolean
 _shell_set_active_panel_from_id (CcShell      *shell,
@@ -823,6 +858,8 @@ _shell_set_active_panel_from_id (CcShell      *shell,
   GIcon *gicon;
   GnomeControlCenterPrivate *priv = GNOME_CONTROL_CENTER (shell)->priv;
 
+  /* clear any custom widgets */
+  _shell_remove_all_custom_widgets (priv);
 
   iter_valid = gtk_tree_model_get_iter_first (GTK_TREE_MODEL (priv->store),
                                               &iter);
@@ -919,6 +956,11 @@ gnome_control_center_dispose (GObject *object)
 {
   GnomeControlCenterPrivate *priv = GNOME_CONTROL_CENTER (object)->priv;
 
+  if (priv->custom_widgets)
+    {
+      g_ptr_array_unref (priv->custom_widgets);
+      priv->custom_widgets = NULL;
+    }
   if (priv->window)
     {
       gtk_widget_destroy (priv->window);
@@ -1005,6 +1047,7 @@ gnome_control_center_class_init (GnomeControlCenterClass *klass)
   object_class->finalize = gnome_control_center_finalize;
 
   shell_class->set_active_panel_from_id = _shell_set_active_panel_from_id;
+  shell_class->embed_widget_in_header = _shell_embed_widget_in_header;
   shell_class->get_toplevel = _shell_get_toplevel;
 }
 
@@ -1083,6 +1126,9 @@ gnome_control_center_init (GnomeControlCenter *self)
   g_signal_connect (gtk_builder_get_object (priv->builder, "home-button"),
                     "clicked", G_CALLBACK (home_button_clicked_cb), self);
 
+  /* keep a list of custom widgets to unload on panel change */
+  priv->custom_widgets = g_ptr_array_new_with_free_func ((GDestroyNotify) g_object_unref);
+
   /* load the available settings panels */
   setup_model (self);