<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function x()
{
  document.removeEventListener("DOMAttrModified", x, false);
  document.removeChild(document.documentElement);
}

function boom()
{
  var p = document.createElementNS("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", "progressmeter");
  document.addEventListener("DOMAttrModified", x, false);
  document.documentElement.appendChild(p);
}
</script>
</head>
<body onload="boom();"></body>
</html>