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" onload="boom();">

 <script type="text/javascript">

 function boom()

 {

   var l = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "listitem");

   l.style.display = "none";

   var c = document.getElementById("c");

   c.parentNode.insertBefore(l, c);

   document.getElementById("listbox").removeChild(document.getElementById("c"));

 }

 </script>

 <listbox id="listbox"><listitem/><listitem id="c"/></listbox>

 </window>