title: wicket modal popup close issue
body: <p>I have a page from where i called a modal pop up. Again on save action I called another confirm modal popup. Now when I click on ok then I am supposed to close both modal pop up. Its working fine in all broswer except IE9 AND Chrome. </p>
  
  <p>Error:</p>
  
  <pre><code>Wicket.Ajax: Wicket.Ajax.Call.failure: Error while parsing response: 
  Could not find root &lt;ajax-response&gt; element wicket-ajax-debug-ver-1356005121064.js:91
  WicketAjaxDebug.logError wicket-ajax-debug-ver-1356005121064.js:91
  Wicket.Log.error wicket-ajax-ver-1356005121064.js:116
  Wicket.Ajax.Call.failure wicket-ajax-ver-1356005121064.js:1098
  Wicket.Ajax.Call.loadedCallback wicket-ajax-ver-1356005121064.js:1297
  Wicket.Ajax.Request.stateChangeCallback wicket-ajax-ver-1356005121064.js:1048
  Wicket.Window.close modal-ver-1356005121079.js:822
  close`enter code here`
  </code></pre>