Steps to Reproduce

comment out workaround in:
http://zkfiddle.org/sample/21s01q9/10-popupradioevent-with-workaround

or

<zk>
<button label="click me" popup="zoomLevelPopup, after_start" />
<popup id="zoomLevelPopup">
 <radiogroup onCheck='Clients.log("index"+self.getSelectedIndex())'>
   <vlayout>
    <radio label="1" />
    <radio label="2" selected="true" />
    <radio label="3"  />
   </vlayout>
 </radiogroup>
</popup>
</zk>

Current Result

Click the radio inside the popup, the radio display appear not be updated.
widget and component values are updated. listeners are triggered.

Expected Result

Popup shouldn't suppress the change of DOM state value causing the display not to be updated.

Debug Info

following
https://github.com/zkoss/zk/commit/ce94d2c16181d60f115416bf703d9a47debd0cdb#diff-c32e17bbb3558712356bc274e4f442e8

Root Cause

event.stop() seem to prevent DOM state update. DOM attributes are updated, but not the element state value.

Workaround

/!\ restore a know issue with popups, popup reopens when clicking content.
<script><![CDATA[
zk.afterLoad('zul.wgt', function() {
var xPopup = {};
zk.override(zul.wgt.Popup.prototype, xPopup ,{
doClick_ : function(evt) {

}
});//zk.override
});//zk.afterLoad
]]></script>