problem releasing QCRenderer

FROM : Dan Treiman
DATE : Tue Jul 25 18:14:21 2006

I have a cocoa app that needs to be able to render compositions at 
different user-selectable resolutions.
I noticed that the QCTV sample at
http://developer.apple.com/samplecode/QuartzComposer_WWDC_QCTV
implements this functionality by releasing its QCRenderers, resizing 
the view/gl context, and then loading new QCRenderers.
However, whenever I try this (even in QCTV) I get an EXC_BAD_ACCESS. 
A backtrace shows

#0  0xfffeff20 in objc_msgSend_rtp ()
#1  0x987e8114 in -[QCPatch(Private) _cleanup] ()
#2  0x987e7fa4 in -[QCPatch(Private) _cleanup] ()
#3  0x987e7eac in -[QCPatch(Runtime) stopRendering] ()
#4  0x9881ec14 in -[QCRenderer dealloc] ()

I'm running 10.4.7, XCode 2.3

Does anybody have any insight into this?  Did this perhaps work in a 
previous version?
   
   thanks,
   -Dan Treiman