<?xml version="1.0"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
<window id="yourwindow" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
<script type="text/javascript">
<![CDATA[
function onload() {
  document.addEventListener("DOMAttrModified", function() {}, true);
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}
]]>
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<progressmeter id="test"/>
</window>