<?xml version="1.0"?>
<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
	onload="var p = document.getElementById('o'); p.insertBefore(document.createElement('box'), p.firstChild);">

<style xmlns="http://www.w3.org/1999/xhtml"><![CDATA[
  outer {
    -moz-binding: url(472020-xbl.xml#outer);
    border: 2px solid yellow;
  }
  inner {
    -moz-binding: url(472020-xbl.xml#inner);
  }
  box {
    width: 50px;
    border: 2px solid green;
  }
]]></style>

  <outer id="o">
    <box/>
  </outer>
</window>