http://bugs.winehq.org/show_bug.cgi?id=23453
--- Comment #7 from Vladimir Panteleev thecybershadow@gmail.com 2010-09-14 03:16:57 CDT --- After a bit of research, I found that Wine's implementation of DM_GETDEFID, and the mentioned commit, seem to be correct as far as this problem is concerned. Windows behaves in the same way as Wine. The fact that DM_GETDEFID returning 0 used to allow MFC applications to function correctly seems to be a coincidence.
The problem probably presides in Wine's IsDialogMessage implementation. Windows sends the WM_COMMAND message which triggers MFC's OnOK, while Wine does not. I will continue my research.