http://bugs.winehq.org/show_bug.cgi?id=30126
--- Comment #6 from Vincent Povirk madewokherd@gmail.com 2012-03-10 15:08:21 CST --- Well, we can't use an HDC for pixel formats with an alpha channel, because gdi32 cannot draw with alpha data. We need a line/curve drawing implementation that doesn't rely on gdi32.