If action provides a #GtkMenu widget as a submenu for the menu item or the toolbar item it creates, this function returns an instance of that menu.
the menu item provided by the action, or null.
Deprecated: Use #GAction and #GMenuModel instead, and create a #GtkMenu with gtk.menu.Menu.newFromModel
If action provides a #GtkMenu widget as a submenu for the menu item or the toolbar item it creates, this function returns an instance of that menu.