[Mediawiki-l] Using templates within extension content

[Paul Wehr]

I was excited to leverage the template facility to map a complex process 
using the graphviz (http://www.mediawiki.org/wiki/Extension:GraphViz) 
extension, which would then be included as a template on each page 
created for a node in the process, then use {{SUBPAGENAMEE}} in the 
template to automatically highlight where in the process graph this page 
documents, a sort of "You are here".

But alas, it appears that parameters (e.g. {{SUBPAGENAME}}), Templates, 
and ParserFunctions ({{#ifeq:...}}) are not interpreted within the 
<graphviz> tags.  I get a graphviz nodes named, literally, "Test", 
"ifeq", and "SUBPAGENAMEE", using:

<graphviz>
digraph g {
Test {{ #ifeq: {{SUBPAGENAMEE}} | Test | [color="yellow"] }};
}
</graphviz>

Is there a way to get the template/extentions parser to mangle the 
graphviz content before graphviz sees it?  Is there an easier way to 
achieve the goal above?  I don't mind modifying the extension scripts, 
or mediawiki, but with otherwise no experience in the code base, anyone 
who could even point me in the right direction would be helpful.