FIX: OnWindowMessage Returns BOOL for HRESULT

• Microsoft Active Template Library, versions 2.0, 2.1 included with: - Microsoft Visual C++, 32-bit Editions, version 5.0

SYMPTOMS

ATL’s IOleInPlaceObjectWindowless::OnWindowMessage implementation mistakenly returns a BOOL instead of an HRESULT indicating failure when it has actually succeeded.

CAUSE

IOleInPlaceObjectWindowless::OnWindowMessage should return S_OK if processed, otherwise S_FALSE.

ATL passes on the return from value pT->ProcessWindowMessage, which returns TRUE if processed, otherwise FALSE.

RESOLUTION

Change the following line of source code in AtlCtl.h line 1829:

   return pT->ProcessWindowMessage(pT->m_hWnd, msg, wParam,
         lParam, *plResult);

to:

   if (pT->ProcessWindowMessage(pT->m_hWnd, msg, wParam,
         lParam, *plResult))
      return S_OK;
   else
      return S_FALSE;

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been corrected in Visual Studio 97 Service Pack 1.

For additional information about the Visual Studio 97 Service Pack 1, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q170365
   TITLE     : INFO: Visual Studio 97 Service Packs - What, Where, and Why