I think I found the problem.
In swell-gdi.mm, line 205 is:
Code:
CGContextRef c=CGBitmapContextCreate(ALIGN_FBUF(buf),w,h,8,w*4,__GetDisplayColorSpace(), kCGImageAlphaNoneSkipFirst);
If I change it to:
Code:
CGContextRef c=CGBitmapContextCreate(ALIGN_FBUF(buf),w,h,8,w*4, __GetBitmapColorSpace(), kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Host);
the color looks correct