2010/2/5 Vincent Povirk <madewokherd+8cd9@gmail.commadewokherd%2B8cd9@gmail.com
It's supported 32bpp with transparency from the start. The full list of supported writing formats is here: http://source.winehq.org/source/dlls/windowscodecs/pngformat.c#L680
GUID_WICPixelFormat32bppBGRA is the format you want, I think.
You probably tried to use a format not on that list, which defaults to 24-bit. I'm not sure what the behavior should be in that case.
That's odd. Both WIC and winemenubuilder appear to be using BGR for 32-bit pixel formats and informing libpng of this . I don't know where you could be getting RGB pixels.
I didn't notice earlier, but you sent in a fix for winemenubuilder. I tested compilation with it and it works fine. Thank you for your attention on this problem.