https://bugs.winehq.org/show_bug.cgi?id=48732
--- Comment #15 from Gabriel Ivăncescu gabrielopcode@gmail.com --- Actually, even if we ignore this bug's peculiarities, I still think I will end up sending the patch to the mailing list (perhaps in a slightly different form).
Zeb, here's my reasoning as to why, perhaps this might persuade you.
First, it's obviously more correct in terms of what Windows does; even if it's an implementation detail, it looks some applications depend on it, so we should IMO implement it as close as possible.
Secondly, when closing Media Player Classic while playing a video, there's a short flashing/flicker window on the top-left of the screen, which appears because of SetParent, which also seems to cause some fast focus changes. This patch fixes that as well, and so is a smoother experience overall.
I think that makes it worth it.