popupMenu, panelMenu: split up panel and non-panel keynav

PopupMenuManager was pretending that it knew nothing about the menu's
sourceActors, while also trying to handle keynav between them. This
was a big mess, and resulted in bugs in navigation between panel menus
and the Activities button, and it totally gets in the way when trying
to add keynav to the dash (whose menu sources are arranged vertically
rather than horizontally).

Fix this up by moving the panel-specific parts to PanelMenuButton
instead.

https://bugzilla.gnome.org/show_bug.cgi?id=641253

src/st/st-focus-manager.c

@@ -199,3 +199,26 @@ st_focus_manager_remove_group (StFocusManager *manager,
 {
   g_hash_table_remove (manager->priv->groups, root);
 }
+
+/**
+ * st_focus_manager_get_group:
+ * @manager: the #StFocusManager
+ * @widget: an #StWidget
+ *
+ * Checks if @widget is inside a focus group, and if so, returns
+ * the root of that group.
+ *
+ * Return value: (transfer none): the focus group root, or %NULL if
+ * @widget is not in a focus group
+ */
+StWidget *
+st_focus_manager_get_group (StFocusManager *manager,
+                            StWidget       *widget)
+{
+  ClutterActor *actor = CLUTTER_ACTOR (widget);
+
+  while (actor && !g_hash_table_lookup (manager->priv->groups, actor))
+    actor = clutter_actor_get_parent (actor);
+
+  return ST_WIDGET (actor);
+}

src/st/st-focus-manager.h

@@ -73,6 +73,8 @@ void            st_focus_manager_add_group     (StFocusManager *manager,
                                                 StWidget       *root);
 void            st_focus_manager_remove_group  (StFocusManager *manager,
                                                 StWidget       *root);
+StWidget       *st_focus_manager_get_group     (StFocusManager *manager,
+                                                StWidget       *widget);
 
 G_END_DECLS