XBL bound tag in a template DOM timing issue

Hi all. Having what I believe is a timing issue here.

<listbox datasources='rdf:null' ref='rdf:null' flex='1'
menu-label='Icon view' class='datasource-library-keyframes'>
  <template>
    <listitem uri='rdf:*' class='large-icon-wrapper'><listcell>
      <vbox>
        <svgloader src='rdf:http://example.com/app/1.0#file'
object='rdf:http://example.com/app/1.0#keyframe' width='64'
height='64' />
        <xul:label value='rdf:http://example.com/app/1.0#keyframe' />
      </vbox>
    </listcell></listitem>
  </template>
</listbox>

(note: datasources and ref attributes of listbox are set in JS on window load)

<binding id='svgloader'>
  <content><svg:svg /></content>
  <implementation>
    <constructor><![CDATA[
     ...
      this.getAttribute('src'); this.getAttribute('object'); // <-- problem code
     ...
    ]]></constructor>
  </implementation>	
</binding>

So the issue is with the two attributes with the comment labeled
"problem code" above. Sometimes these attributes read the value from
the attached RDF just fine. Other times, I get back an empty string.
It seems fairly random whether it works or not.

My hackish fix is:

<constructor><![CDATA[
    var svgwrapper = this;
    window.setTimeout(function() {
      svgwrapper.getAttribute('src');
svgwrapper.getAttribute('object'); // <-- works!
    }, 50, []);
]]></constructor>

I'm thinking the only way to do this correctly is to climb the parents
of the bound element, looking for a .builder property. If I find one,
addListener(), and wait for didRebuild() to get called. If I don't
find one, then I can call getAttribute() immediately.

Is that really the solution? Seems like a ton of code just to support
attributes that happen to be in a template.

Thanks in advance for any advice!

Cheers,

--fletch