wine-1.5.10 and higher can make use of libOSMesa from media-libs/mesa[osmesa] for opengl rendering in bitmaps (see http://www.winehq.org/announce/1.5.10). Could you please add a revision bump of app-emulation/emul-linux-x86-opengl that provides a 32-bit version of libOSMesa?
Also, please add osmesa.pc if emul-linux-x86-opengl is emerged with USE=development.
I am fine with it, but I think X11 team was working on building 32bits libs in mesa to allow more flexibility. I tell you this as information, as I probably won't have time to work on a new emul set just now (I am still updating my laptop, reviewing mails... and also need to be in lab for hours :S)
quick recomendation - FireBurn overlay :)
done in latest bump