KB177103 - FIX: ALT+Key Combination in Property Page Causes Stack Overflow

Article ID: 177103

Article Last Modified on 11/21/2006

Microsoft Foundation Class Library 4.2, when used with:
- Microsoft Visual C++ 5.0 Enterprise Edition
- Microsoft Visual C++ 5.0 Professional Edition

This article was previously published under Q177103

SYMPTOMS

If you press an ALT+key combination (generating a WM_SYSCOMMAND) with keyboard focus on the property page for an MFC ActiveX control and the key does not correspond to a mnemonic on the page, you will get a stack overflow.

CAUSE

COlePropertyPage::WindowProc() traps the WM_SYSCOMMAND and calls IPropertyPageSite::TranslateAccelerator(). This function in turns sends the WM_SYSCOMMAND message back to the page. This results in a recursion until you run out of stack space.

RESOLUTION

Override COlePropertyPage::WindowProc() and return TRUE if the message is a WM_SYSCOMMAND; for example:


   LRESULT CMyPropPage::WindowProc(UINT msg, WPARAM wParam, LPARAM lParam)
   {

      //Return without processing if WM_SYSCOMMAND.
      if (WM_SYSCOMMAND == msg)
         return TRUE;
      else
         return COlePropertyPage::WindowProc(msg, wParam, lParam);
   }

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was corrected in Visual C++ version 6.0 for Windows.

REFERENCES

Additional query words: mfcole Stock PropertyPage CLSID_CFontPropPage CLSID_CColorPropPage CLSID_CPicturePropPage

Keywords: kbbug kbdlg kbfix kbvc600fix KB177103