http://bugs.winehq.org/show_bug.cgi?id=14664
--- Comment #4 from Lei Zhang thestig@google.com 2008-12-16 20:19:07 --- http://source.winehq.org/source/dlls/gdi32/bitmap.c#L276
That check was designed to catch things like this, except we have an integer overflow and the computed result on the left side comes out negative.