{
  m_wndMDIClient.Detach();
  //.................
}

int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
  if (CMDIFrameWnd::OnCreate(lpCreateStruct) == -1)
    return -1;

    if (m_wndMDIClient.Attach(m_hWndMDIClient) == 0)
    {
        TRACE0("Failed to attach MDIClient.\n");
        return -1;      // fail to create
    }
  //.................
}

//----------------------------------------------------------------
// This function finds the CMDIChildWnd in the list of Windows
// maintained by the application's MDIClient window following the
// one pointed to by the member variable m_pWndCurrentChild. If no
// further CMDIChildWnds are in the list, NULL is returned.
//----------------------------------------------------------------

CMDIChildWnd* CMainFrame::GetNextMDIChildWnd()
{
   if (!m_pWndCurrentChild)
     {
      // Get the first child window.
      m_pWndCurrentChild = m_wndMDIClient.GetWindow(GW_CHILD);
     }
   else
     {
      // Get the next child window in the list.
        m_pWndCurrentChild=
           (CMDIChildWnd*)m_pWndCurrentChild->GetWindow(GW_HWNDNEXT);
     }

   if (!m_pWndCurrentChild)
     {
      // No child Windows exist in the MDIClient,
      // or you are at the end of the list. This check
      // will terminate any recursion.
      return NULL;
     }

  // Check the kind of window
    if (!m_pWndCurrentChild->GetWindow(GW_OWNER))