<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
        xmlns:html="http://www.w3.org/1999/xhtml"
        xmlns:math="http://www.w3.org/1998/Math/MathML"
        class="reftest-wait"
        onload="boom();">
        
<html:style type="text/css">
[class="mp"] { display: -moz-popup; }
</html:style>

<script>

function boom()
{
  document.getElementById("mtd").setAttribute("class", "mp");
  setTimeout(boom2, 30);
}

function boom2()
{
  document.getElementById("mtd").setAttribute("class", "");
  document.documentElement.removeAttribute("class");
}

</script>

<math:mtd id="mtd" />

</window>