I think I'm finished implementing custom fill styles. It works with the single symbol, unique value and graduated symbol renderers, and appears to correctly save and load the fill styles.<br>I have filed an enhancement in trac, and attached the patch:
<a href="https://svn.qgis.org/trac/ticket/731">#731</a>. Sorry if I should have filed it as a patch instead. I'm just learning a lot of this, so if I should have done something differently with the code or patch, let me know and I'll be glad to fix it.
<br>Steven<br>