Steps to Reproduce

1. run the zul with 8.5.2.FL.20180703-Eval

<zk>
	<zscript><![CDATA[
	public void show(){
        Clients.showNotification("test");
	}
	]]></zscript>
    <button label="notification" onClick="show()" />
</zk>

2. click the button

Current Result

The notification doesn't disappear after clicking out of the notification.

zk.wpd:37323 Uncaught TypeError: Cannot read property '$n' of null
at init.position (zk.wpd:37323)
at init.afterOpenAnima_ (zk.wpd:34825)
at HTMLDivElement.<anonymous> (zk.wpd:37432)
at HTMLDivElement.opt.complete (zk.wpd:9663)
at fire (zk.wpd:3231)
at Object.fireWith [as resolveWith] (zk.wpd:3344)
at tick (zk.wpd:9118)
at jQuery.fx.tick (zk.wpd:9695)

Expected Result

no error

Debug Information

• 8.5.1.2 has no such issue