<?xml version="1.0"?>
<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" onload="boom();">
        
<bindings xmlns="http://www.mozilla.org/xbl">
  <binding id="empty"><content></content></binding>
</bindings>

<script type="text/javascript">

function boom()
{
  var menupopup = document.getElementById("menupopup");
  var x = SpecialPowers.wrap(document).getAnonymousNodes(menupopup)[0];
  menupopup.style.MozBinding = "url('#empty')";
  for (var ppp in x) {
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}

</script>

<menupopup id="menupopup"/>

</window>