Wow, good that some one asked about this eventually.
I did notice this too on Win since a longtime ago on an lower-spec PC with an Intel based directx 9 vidcard (actually not "that" lower spec pc, it is a PIV 2.smthin GHz, 1Gb DDRAM, but only the vidcard maybe, not sure what opengl supports).
The "bug" does happen only when using a different than directx vo.
Win version does not seem to have that option though so is it maybe a ini setting that I can use?
Also, that does not happen all the time but in 90% cases of making the video fullscreen.
Cheers.