class TCtrl:
        public CWindowImpl< TCtrl>, 
        public WTL::CDoubleBufferImpl<TCtrl>  // 繼承雙緩沖類

 BEGIN_MSG_MAP(TCtrl)
//        MESSAGE_HANDLER(WM_PAINT,        OnPaint)
        CHAIN_MSG_MAP( WTL::CDoubleBufferImpl<TCtrl>)
    END_MSG_MAP()

void DoPaint(CDCHandle dc);

void TCtrl::DoPaint( CDCHandle dc )
{
    //CPaintDC dc(m_hWnd);     dc.MoveTo( xx… )}