http://bugs.winehq.org/show_bug.cgi?id=2812
--- Comment #17 from Dmitry Timoshkov dmitry@codeweavers.com 2008-01-07 23:24:48 --- (In reply to comment #12)
(Confirmed) I should add that it's not only a hack but also incomplete - lParam needs to be wrapped for more messages but I didn't bother. See mciwnd.c.
Also the patch should use SetWindowLongPtrA instead of SetWindowLongPtrW, and use CallWindowProc to call an old window proc.
Otherwise the patch should be sent to wine-patches, it's an improvement.