<treeitem xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
<splitter/>
<splitter>
  <splitter id="a"/>
</splitter>

<script xmlns="http://www.w3.org/1999/xhtml">
 document.getElementById('a').setAttribute('a', 'a');
</script>

<style xmlns="http://www.w3.org/1999/xhtml">
treeitem, splitter {-moz-binding:url(data:text/xml;charset=utf-8,%3Cbindings%20xmlns%3D%22http%3A//www.mozilla.org/xbl%22%3E%3Cbinding%20id%3D%22a%22%3E%3Ccontent%3E%3Cchildren/%3E%3C/content%3E%3C/binding%3E%3C/bindings%3E);}
</style>

</treeitem>