FIX: ActiveX Control Fails to Fire Click Event

The information in this article applies to:

• Microsoft Visual C++, 32-bit Edition, version 4.2

SYMPTOMS

If you create an ActiveX control that subclasses a button, you may find that the control doesn't fire a "click" event. You can observe this behavior by running the BUTTON sample included with Visual C++ 4.2.

CAUSE

There is a bug in the COleControl::OnLButtonUp() function. CWnd::OnLButtonUp() should be called within the function before calling COleControl::ButtonUp().

RESOLUTION

You can work around the problem by trapping the WM_LBUTTONUP message in your control. Copy the code from the OnLButtonUp() function located in \MSDEV\MFC\SRC\CTLEVENT.CPP and place it into your new handler. Move the call to CWnd::OnLButtonUp() before the call to ButtonUp() so that the new function looks like the following:

   void CYourButtonCtrl::OnLButtonUp(UINT nFlags, CPoint point)
   {
      HWND hWndSave = m_hWnd;
      CWnd::OnLButtonUp(nFlags, point);  // moved the call here

           ButtonUp(LEFT_BUTTON, nFlags, point);
      if (m_hWnd != hWndSave)
         return;

      if (m_bInPlaceActive && !m_bUIActive && m_bPendingUIActivation &&
         (GetFocus() == this || IsChild(GetFocus())))
      {
         m_bPendingUIActivation = FALSE;
         OnActivateInPlace(TRUE, NULL);
      }
   }

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug was corrected in Visual C++ version 4.2b.

REFERENCES

For more information about Visual C++ 4.2b, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q156934
   TITLE     : PATCH: Visual C++ 4.2b Patch