FIX: CWindow::GetTopLevelWindow() Returns NULL

ID: Q168123

The information in this article applies to:

Microsoft Active Template Library, version 2.1

SYMPTOMS

A call to CWindow::GetTopLevelWindow() always returns NULL.

CAUSE

This is due to a bug in the function.

RESOLUTION

Change the function in AtlWin.cpp from:


   HWND CWindow::GetTopLevelWindow() const
   {
      ...
      while(hWndTmp != NULL)
      {
         hWndTmp = (::GetWindowLong(hWndParent, GWL_STYLE) & WS_CHILD) ?
            ::GetParent(hWndParent) :
            ::GetWindow(hWndParent, GW_OWNER);

         hWndParent = hWndTmp;
      }

      return hWndParent;
   }

to the following: HWND CWindow::GetTopLevelWindow() const { ... while(hWndTmp != NULL) { // Modification hWndParent = hWndTmp; hWndTmp = (::GetWindowLong(hWndParent, GWL_STYLE) & WS_CHILD) ? ::GetParent(hWndParent) : ::GetWindow(hWndParent, GW_OWNER); } return hWndParent; }

STATUS

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

(c) Microsoft Corporation 1997, All Rights Reserved. Contributions by Sridhar Madhugiri, Microsoft Corporation

Additional query words: GetTopLevelWindow NULL kbatl210bug kbctrl kbvc600fix kbserver kbinternet

Keywords : kbATL210bug kbATLWC kbInprocSvr kbServer kbVC500bug kbVC600fix kbATL300fix kbGrpMFCATL
Version :
Platform : WINDOWS
Issue type : kbbug