[Bug 7360] hiding child incorrectly sets an update region on the grandparent

[Wine Bugs]

http://bugs.winehq.org/show_bug.cgi?id=7360

------- Additional Comments From [e-mail]  2007-12-02 00:16 -------
> From the e-mail I sent to wine-devel:

After looking at this test once more, I think we need another test with
windows without CS_PARENTDC style set in order to understand better what
the proper behaviour is.