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

• The Microsoft Foundation Classes (MFC), included with:
  • Microsoft Visual C++, 32-bit Editions, versions 5.0sp1, 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

Keywords : kbcode kbservicepack kbMFC KbUIDesign kbVC kbVC500bug kbVS97sp1bug kbVS97sp2bug kbVS97sp3fix
Version : WINDOWS NT:5.0sp1,5.0sp2
Platform : NT WINDOWS
Issue type : kbbug