gtkwindow: Use actions from focused widget to activate accel

Currently we only take into account the window GActionGroup for
activating the accels.

However, the application could have some custom GActionGroup in the
chain of focused widgets that could want to activate some action if
some accel is activated while that widget is focused.

To allow applications to set accels on widgets that use custom
GActionGroups, simply use the muxer of the focused widget, which
already contains the actions of the parents.

https://bugzilla.gnome.org/show_bug.cgi?id=740682

gtk/gtkactionhelper.c

@@ -397,7 +397,7 @@ gtk_action_helper_new (GtkActionable *widget)
         g_object_get (G_OBJECT (helper->widget), "active", &helper->active, NULL);
     }
 
-  helper->action_context = _gtk_widget_get_action_muxer (GTK_WIDGET (widget));
+  helper->action_context = _gtk_widget_get_action_muxer (GTK_WIDGET (widget), TRUE);
 
   return helper;
 }

gtk/gtkmenusectionbox.c

@@ -379,7 +379,7 @@ gtk_menu_section_box_new_toplevel (GtkStack    *stack,
   box = g_object_new (GTK_TYPE_MENU_SECTION_BOX, "margin", 10,  NULL);
   gtk_stack_add_named (stack, GTK_WIDGET (box), "main");
 
-  box->tracker = gtk_menu_tracker_new (GTK_ACTION_OBSERVABLE (_gtk_widget_get_action_muxer (GTK_WIDGET (box))),
+  box->tracker = gtk_menu_tracker_new (GTK_ACTION_OBSERVABLE (_gtk_widget_get_action_muxer (GTK_WIDGET (box), TRUE)),
                                        model, TRUE, FALSE, action_namespace,
                                        gtk_menu_section_box_insert_func,
                                        gtk_menu_section_box_remove_func, box);

gtk/gtkmenushell.c

@@ -2194,7 +2194,7 @@ gtk_menu_shell_bind_model (GtkMenuShell *menu_shell,
   g_return_if_fail (GTK_IS_MENU_SHELL (menu_shell));
   g_return_if_fail (model == NULL || G_IS_MENU_MODEL (model));
 
-  muxer = _gtk_widget_get_action_muxer (GTK_WIDGET (menu_shell));
+  muxer = _gtk_widget_get_action_muxer (GTK_WIDGET (menu_shell), TRUE);
 
   g_clear_pointer (&menu_shell->priv->tracker, gtk_menu_tracker_free);
 

gtk/gtkwidget.c

@@ -16481,45 +16481,54 @@ _gtk_widget_set_style (GtkWidget *widget,
   widget->priv->style = style;
 }
 
+GtkActionMuxer *
+_gtk_widget_get_parent_muxer (GtkWidget *widget,
+                              gboolean   create)
+{
+  GtkWidget *parent;
+
+  if (GTK_IS_WINDOW (widget))
+    return gtk_application_get_parent_muxer_for_window (GTK_WINDOW (widget));
+
+  if (GTK_IS_MENU (widget))
+    parent = gtk_menu_get_attach_widget (GTK_MENU (widget));
+  else if (GTK_IS_POPOVER (widget))
+    parent = gtk_popover_get_relative_to (GTK_POPOVER (widget));
+  else
+    parent = gtk_widget_get_parent (widget);
+
+  if (parent)
+    return _gtk_widget_get_action_muxer (parent, create);
+
+  return NULL;
+}
+
 void
 _gtk_widget_update_parent_muxer (GtkWidget *widget)
 {
-  GtkActionMuxer *parent_muxer;
-
   if (widget->priv->muxer == NULL)
     return;
 
-  if (GTK_IS_WINDOW (widget))
+  gtk_action_muxer_set_parent (widget->priv->muxer,
-    {
+                               _gtk_widget_get_parent_muxer (widget, TRUE));
-      parent_muxer = gtk_application_get_parent_muxer_for_window (GTK_WINDOW (widget));
-    }
-  else
-    {
-      GtkWidget *parent;
-
-      if (GTK_IS_MENU (widget))
-        parent = gtk_menu_get_attach_widget (GTK_MENU (widget));
-      else if (GTK_IS_POPOVER (widget))
-        parent = gtk_popover_get_relative_to (GTK_POPOVER (widget));
-      else
-        parent = gtk_widget_get_parent (widget);
-
-      parent_muxer = parent ? _gtk_widget_get_action_muxer (parent) : NULL;
-    }
-
-  gtk_action_muxer_set_parent (widget->priv->muxer, parent_muxer);
 }
 
 GtkActionMuxer *
-_gtk_widget_get_action_muxer (GtkWidget *widget)
+_gtk_widget_get_action_muxer (GtkWidget *widget,
+                              gboolean   create)
 {
-  if (widget->priv->muxer == NULL)
+  if (widget->priv->muxer)
+    return widget->priv->muxer;
+
+  if (create)
     {
       widget->priv->muxer = gtk_action_muxer_new ();
       _gtk_widget_update_parent_muxer (widget);
-    }
 
-  return widget->priv->muxer;
+      return widget->priv->muxer;
+    }
+  else
+    return _gtk_widget_get_parent_muxer (widget, FALSE);
 }
 
 /**
@@ -16548,7 +16557,7 @@ gtk_widget_insert_action_group (GtkWidget    *widget,
   g_return_if_fail (GTK_IS_WIDGET (widget));
   g_return_if_fail (name != NULL);
 
-  muxer = _gtk_widget_get_action_muxer (widget);
+  muxer = _gtk_widget_get_action_muxer (widget, TRUE);
 
   if (group)
     gtk_action_muxer_insert (muxer, name, group);

gtk/gtkwidgetprivate.h

@@ -151,7 +151,8 @@ void              _gtk_widget_invalidate_style_context     (GtkWidget    *widget
 void              _gtk_widget_style_context_invalidated    (GtkWidget    *widget);
 
 void              _gtk_widget_update_parent_muxer          (GtkWidget    *widget);
-GtkActionMuxer *  _gtk_widget_get_action_muxer             (GtkWidget    *widget);
+GtkActionMuxer *  _gtk_widget_get_action_muxer             (GtkWidget    *widget,
+                                                            gboolean      create);
 gchar **          _gtk_widget_list_action_prefixes         (GtkWidget    *widget);
 GActionGroup *    _gtk_widget_get_action_group             (GtkWidget    *widget,
                                                             const gchar  *prefix);

gtk/gtkwindow.c

@@ -11214,7 +11214,12 @@ gtk_window_activate_key (GtkWindow   *window,
 
               if (window->priv->application)
                 {
-                  GtkActionMuxer *muxer = _gtk_widget_get_action_muxer (GTK_WIDGET (window));
+                  GtkWidget *focused_widget = gtk_window_get_focus (window);
+                  if (focused_widget == NULL)
+                    return FALSE;
+                  GtkActionMuxer *muxer = _gtk_widget_get_action_muxer (focused_widget, FALSE);
+                  if (muxer == NULL)
+                    return FALSE;
 
                   return gtk_application_activate_accel (window->priv->application,
                                                          G_ACTION_GROUP (muxer),