Q172276: FIX: CToolTipCtrl Not Displaying Text After VS SP1, SP2 Install

Article: Q172276
Product(s): Microsoft C Compiler
Version(s): winnt:5.0sp1,5.0sp2
Operating System(s): 
Keyword(s): kbMFC kbToolTip KbUIDesign kbVC500bug kbVS97sp1bug kbVS97sp2bug kbVS97sp3fix kbGrpDSMFC
Last Modified: 17-JUL-2001

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The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0sp1 
   - Microsoft Visual C++, 32-bit Professional Edition, version 5.0sp1 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0sp2 
   - Microsoft Visual C++, 32-bit Professional Edition, version 5.0sp2 
-------------------------------------------------------------------------------

SYMPTOMS
========

Applications that use CWnd::EnableTooltips to use a default CToolTipCtrl do not
display the tooltip text for child windows after the Visual Studio Service Pack
1 (SP1) or Service Pack 2 (SP2) has been installed.

Other CToolTipCtrls and Tooltips inside of CToolBars work correctly.

CAUSE
=====

The cbSize parameter of the TOOLINFO struct was changed to be of size
AfxOldTOOLINFO to be compatible with older versions of the COMCTL32.DLL.

CWnd::OnToolHitTest() was not changed, and is dependent on the cbSize to be equal
to the size of the new TOOLINFO struct. Since cbSize is always set to
AfxOldTOOLINFO, this function fails.

RESOLUTION
==========

Override the virtual function CWnd::OnToolHitTest() to take into account the new
cbSize value.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug has been fixed in Visual Studio 97 Service
Pack 3.

For more information, please see the following article in the Microsoft Knowledge
Base:

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

MORE INFORMATION
================

Here is a sample OnToolHitTest() that implements the workaround:

     #include <WTYPES.H>
     #include "..\src\afximpl.h"

     int CSuperTipFormView::OnToolHitTest(CPoint point, TOOLINFO* pTI) const
     {

        HWND hWndChild = NULL;
        // find child window which hits the point
        // (don't use WindowFromPoint, because it ignores disabled windows)
        // see _AfxChildWindowFromPoint(m_hWnd, point);
        ::ClientToScreen(m_hWnd, &point);
        HWND hChild = ::GetWindow(m_hWnd, GW_CHILD);
        for (; hChild != NULL; hChild = ::GetWindow(hChild, GW_HWNDNEXT))
        {
           if (_AfxGetDlgCtrlID(hChild) != (WORD)-1 &&
                 (::GetWindowLong(hChild, GWL_STYLE) & WS_VISIBLE))
           {
              // see if point hits the child window
              CRect rect;
              ::GetWindowRect(hChild, rect);
              if (rect.PtInRect(point))
              {
                 hWndChild = hChild;
                 break;
              }
           }
        }

        if (hWndChild != NULL)
        {
           // return positive hit if control ID isn't -1
           int nHit = _AfxGetDlgCtrlID(hWndChild);

           // hits against child windows always center the tip
           if (pTI != NULL && pTI->cbSize >= sizeof(AfxOldTOOLINFO))
           {
              // setup the TOOLINFO structure
              pTI->hwnd = m_hWnd;
              pTI->uId = (UINT)hWndChild;
              pTI->uFlags |= TTF_IDISHWND;
              pTI->lpszText = LPSTR_TEXTCALLBACK;

         // set TTF_NOTBUTTON and TTF_CENTERTIP if it isn't a button
         if (!(::SendMessage(hWndChild, WM_GETDLGCODE, 0, 0) &
                    DLGC_BUTTON))
                 pTI->uFlags |= TTF_NOTBUTTON|TTF_CENTERTIP;
           }
           return nHit;
        }
        return -1;  // not found
     }

REFERENCES
==========

For additional information, please see the following article in the Microsoft
Knowledge Base:

  Q167650 FIX: Problems with ToolTips on Windows 95

Additional query words:

======================================================================
Keywords          : kbMFC kbToolTip KbUIDesign kbVC500bug kbVS97sp1bug kbVS97sp2bug kbVS97sp3fix kbGrpDSMFCATL kbNoUpdate 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:5.0sp1,5.0sp2
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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