BUG: GetDlgItem() Returns NULL Under Win32s

• The Microsoft Foundation Classes (MFC) included with: - Microsoft Visual C++, 32-bit Edition, versions 4.0, 4.1

SYMPTOMS

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.

CAUSE

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.

RESOLUTION

Remove all extended styles in all the controls in the dialog resource.

STATUS

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 available.

Visual C++ versions 4.2 and later do not support building Win32s applications.

MORE INFORMATION

For additional information, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q138971
   TITLE     : BUG: Default Dialog-Based Application Doesn't Work in
               Win32s