protected internal override Gtk.ToolItem CreateToolItem(CommandManager manager)
 {
     Gtk.Menu menu = manager.CreateMenu (this);
     return new MenuToolButton (menu, icon);
 }
 protected internal override Gtk.MenuItem CreateMenuItem(CommandManager manager)
 {
     Gtk.MenuItem mi = new Gtk.MenuItem (name != null ? name : "");
     mi.Submenu = manager.CreateMenu (this);
     return mi;
 }