Help ,about the sample of MDITabWindow

I want to close a document by double click the tab;

 

so I modify the function of  CMainFrame::OnTabbarMouseMsg like this:

 

LRESULT CMainFrame::OnTabbarMouseMsg(WPARAM wParam,LPARAM lParam)
{
 if (wParam == WM_LBUTTONDBLCLK) 

 {
  CPoint point = CPoint((DWORD)lParam);
  
  CXTPTabManagerItem* pItem =  m_MTIClientWnd.HitTest(point);
  if (pItem)
  {
   CWnd* pActiveChildWnd = MDIGetActive(NULL);
   if (pActiveChildWnd)
   {
    pActiveChildWnd->SendMessage(WM_COMMAND, ID_FILE_CLOSE);    }
   return TRUE;
  }
 }

 

..............

}

 

but there is no any response when I double click the tab;

 

I search it by google;find a theme about it ;but it was deleted; I can't open that page;

 

my version is 9.60 ,it is sait that's a but in ver9.60;how to fix it?

 

Thanks a lot!!!