BUG: CToolTipCtrl Stops Working After Dialog Is Displayed

• The Microsoft Foundation Classes (MFC) included with: Microsoft Visual C++, 32-bit Edition, versions 4.0, 4.1, 4.2, 5.0

SYMPTOMS

If you create a CToolTipCtrl and call AddTool() to activate it, it will work until you display a modal dialog box. For example, if on the Help menu, you click About to display the About box, and you then click OK to dismiss it, the CToolTipCtrl will not pop up anymore.

CAUSE

MFC is sending a WM_DISABLEMODAL to all of the frame's descendant windows when a modal dialog box pops up. The CToolTipCtrl responds to the WM_DISABLEMODAL by sending itself a TTM_ACTIVATE with a FALSE. This disables it. However, the CToolTipCtrl doesn't reactivate itself once the frame calls EnableWindow() for its descendants.

RESOLUTION

You should have a PreTranslateMessage() function where you are calling RelayEvent(). The workaround for this problem is to call Activate(TRUE) before the call to RelayEvent().

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

This is only a problem if you create your own CToolTipCtrl. Using EnableToolTips() does not have this problem.

Sample Code to Demonstrate Problem

   // m_pToolTip is a CToolTipCtrl *
   BOOL CTestView::PreTranslateMessage(MSG* pMsg)
   {
       switch(pMsg->message)
       {
           case WM_MOUSEMOVE:
           case WM_LBUTTONDOWN:
           case WM_LBUTTONUP:
           case WM_MBUTTONDOWN:
           case WM_MBUTTONUP:
           case WM_RBUTTONDOWN:
           case WM_RBUTTONUP:
               // This will reactivate the tooltip
               m_ToolTip.Activate (TRUE);
               m_ToolTip.RelayEvent (pMsg);
       }
       return CFormView::PreTranslateMessage(pMsg);
   }

   /* Compile options needed: default
   */