<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script type="text/javascript">
<![CDATA[

function boom()
{
  var XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
  var prefs = document.createElementNS(XUL_NS, "preferences");
  var textbox = document.createElementNS(XUL_NS, "textbox");
  textbox.setAttribute("onchange", "1");
  prefs.appendChild(textbox);
  prefs.cloneNode(true);
}

]]>
</script>
</head>

<body onload="boom();"></body>
</html>