http://bugs.winehq.org/show_bug.cgi?id=23707
--- Comment #6 from Vincent Povirk madewokherd@gmail.com 2010-07-19 08:50:26 --- Sorry, the GWLP_HWNDPARENT naming is rather confusing, and my description didn't help.
GWLP_HWNDPARENT actually sets a window's owner, not it's parent, which makes it completely different from the SetParent function.
The testcase does not crash on Windows, but I have not verified that the owner is really being set.