Calling GetDlgItem() to get the CWnd pointer of a control in a dialog can
fail and return NULL under Win32s. DoDataExchange(), which calls DDX
functions, also ends up calling GetDlgItem(). This can result in an assert
in Dlgdata.cpp, line 43.
This is caused by having extended styles in any of the controls in the
dialog. Any extended style converts the dialog resource to a DIALOGEX
resource. Win32s does not support DIALOGEX resources. None of the controls
in the dialog are be created and the dialog does not display correctly. For
details on how to replace the DIALOGEX style, please see the "More
Information" section of this article.
Remove all extended styles in all the controls in the dialog resource.
Microsoft has confirmed this to be a bug in the Microsoft products listed
at the beginning of this article. We are researching the problem and will
post new information here in the Microsoft Knowledge Base as it becomes
Visual C++ versions 4.2 and later do not support building Win32s
For additional information, please see the following article in the
Microsoft Knowledge Base:
BUG: Default Dialog-Based Application Doesn't Work in Win32s