https://bugs.winehq.org/show_bug.cgi?id=42585
--- Comment #5 from Rafał Mużyło galtgendo@o2.pl --- Updating with more recent info: instead of the mentioned hack, it would seem that the problem is in a slightly different place - not in GdipDrawString (actually in one of its subfunctions), but in GdipGraphicsClear.
Note a detail about those calls: clear color is 0xffffff, not 0xffffffff. Meaning, that clears with a transparent color are supposed to do something, instead - as it's the case now - be silently ignored. Here, resetting the color to 0xff000000 (in case of image being GpBitmap) offers what seems to be proper result, but I have no idea what should be the generic case.