FIX: Registered Message in a USRDLL May Cause a GPF

The information in this article applies to:

• The Microsoft Foundation Classes (MFC), included with: Microsoft Visual C++ for Windows, version 1.0

SYMPTOMS

Using a registered message in a USRDLL may cause a general protection fault (GPF).

CAUSE

The CWnd::WindowProc() function does not calculate the address of the registered message correctly.

RESOLUTION

To avoid the problem, do one of the following:

• Upgrade to Visual C++ for Windows, version 1.5, since this problem was fixed in the MFC library, version 2.5.

  -or-

• Modify the CWnd::WindowProc() function in the MFC library source code and rebuild the USRDLL version of the library. To do this, change line 908 of the file WINCORE.CPP from

         #ifndef _WINDLL
  

  to

         #ifndef _AFXDLL
  

  After making this change, rebuild the USRDLL version of the MFC library by following the procedure outlined on page 303 of Appendix B in the "Class Library User's Guide."

STATUS

Microsoft has confirmed this to be a problem in Visual C++ for Windows, version 1.0. This problem was corrected in Visual C++ for Windows, version 1.5. This is not a problem in Visual C++ 32-bit Edition.