http://bugs.winehq.org/show_bug.cgi?id=15011
--- Comment #6 from Vincent Povirk madewokherd@gmail.com 2009-12-13 20:18:54 --- I guess gdiplus needs support for multi-frame gif files. This is implemented in windowscodecs.
According to MSDN (I'm choosing to believe MSDN for now, but I'll have to test this), switching to a new frame discards the current image data rather than saving it anywhere, meaning that we can read image data directly from the file. I think that we could implement this by saving an open WIC decoder object and attaching it to the Image object.
(I'm mostly commenting so I don't forget and have to look this up again.)