code: function _initNavigationMenuItems() {
          var menu = Menus.getMenu(Menus.AppMenuBar.NAVIGATE_MENU);
          menu.addMenuItem(NAVIGATION_JUMP_BACK, "", Menus.AFTER, Commands.NAVIGATE_PREV_DOC);
          menu.addMenuItem(NAVIGATION_JUMP_FWD, "", Menus.AFTER, NAVIGATION_JUMP_BACK);
      }
docs: Function to initialize navigation menu items.
  @private