Travis put together some tests for me to run on 10.6, while he ran the same ones on 10.5. What we found out is that the double buffering "problem" I reported here is a symptom, not the actual problem. The actual problem is with some level of Pixmap drawing on OS X within our VM, and double buffering - for apps that do a lot of updating, like BottomFeeder - can end up in a pathological state.

That's easy enough to address on an application level basis - just don't use double buffering, or, as I did in BottomFeeder, derive a new double buffering class in its own namespace, have that class notice "oops, I'm on OS X", and pass back the regular policy. For many other apps, double buffering won't be a problem though.

So - if you run on OSX and see this problem go ahead and work around it for now. In the meantime, our VM team is looking at the problem.

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