> So it looks like RGB the macro was not expanded.

Ok now I get why you're taking me down this road. The preprocessor code should show expansions of all macros and the idea is to see whether or not that's happening.

> The question is why.  Is it possible that private.h is included before the Windows headers?

I suppose so but I'm not sure how to figure this out. private.h is withing the wxWidgets installation. I don't know right now what part of the code includes the windows headers. I can just look around when I get home. Is there an "expected" way this should be working?