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

• The Microsoft Foundation Classes (MFC), used with:
  • Microsoft Visual C++, 32-bit Editions, version 5.0

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 this to be a problem in the Microsoft products listed at the beginning of this article. This problem was corrected in Visual C++ version 6.0 for Windows.

REFERENCES

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Samson Tanrena, Microsoft Corporation.

Additional query words: mfcole Stock PropertyPage CLSID_CFontPropPage CLSID_CColorPropPage CLSID_CPicturePropPage

Keywords : kbole kbMFC kbVC500bug kbVC600fix
Version : winnt:5.0
Platform : winnt
Issue type : kbbug