ext中Window窗体显示在最前面的解决办法

var tab1GroupMgr = new Ext.WindowGroup();
//前置窗口
tab1GroupMgr.zseed=99999;?

var addWin = new Ext.Window({
??? title: "添加产品类别",
??? pageX: 50,
??? pageY: 50,
??? width: 600,
??? height: 200,
??? plain: true,
??? manager: tab1GroupMgr,