http://bugs.winehq.org/show_bug.cgi?id=22941
--- Comment #12 from Dmitry Timoshkov dmitry@codeweavers.com 2010-06-14 09:22:34 --- (In reply to comment #11)
Were there specific applications that did not handle well a click in HTCLOSE?
It's Firefox.
Or there were some that wanted specifically Alt-F4?
A cleaner alternative would be to post WM_SYSCOMMAND / SC_CLOSE in which both the above should result.
That breaks Winword 2003. And there were other broken applications around as well.