<?xml version="1.0"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
<window
  xmlns:html="http://www.w3.org/1999/xhtml"
  xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
  <description id="foo">This text should appear bold after onload.</description>
  <script type="application/javascript"><![CDATA[
window.addEventListener("load", function setStyle(evt) {
  document.getElementById("foo").style.fontWeight = "bold";
}, true);
  ]]></script>
</window>