The Tor Browser / file revision

 <?xml version="1.0"?>

 <?xml-stylesheet href="chrome://global/skin/" type="text/css"?>

 <window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" class="reftest-wait" onload="setTimeout(boom, 30);">

 <script><![CDATA[

 function boom()

 {

   var XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";

   var popupgroup = document.createElementNS(XUL_NS, 'popupgroup');

   document.documentElement.appendChild(popupgroup);

   document.documentElement.removeChild(popupgroup);

   var tooltip = document.createElementNS(XUL_NS, 'tooltip');

   document.documentElement.appendChild(tooltip);

   document.documentElement.removeAttribute("class");

 }

 ]]></script>

 </window>