Please call 'showItem' or 'hideItem' methods to display or hide a menu item. These two methods are extended in the patch file, which can be downloaded from
http://www.jeasyui.com/download/downloads/jquery-easyui-1.3.6-patch.zip. The code below shows how to display a menu item.
var item = $('#mm').menu('findItem', 'Open');
$('#mm').menu('showItem', item.target);