如何知道CListBox什么时候滚动了?

每次绘制列表框都要重绘某项,通过消息WM_CTLCOLOR从父窗口获得DC颜色.因此每欠列表框的滚动你都可以用WM_CTLCOLOR来检验是否滚动.

HBRUSH CParentDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
   // is the control _the_ list box we're interested in?
   if( nCtlColor == CTLCOLOR_LISTBOX &&
      pWnd->GetDlgCtrlID() == IDC_LIST )
   {
      // if the top index changed, the list box has been scrolled

      int iTop = ((CListBox*)pWnd)->GetTopIndex();

      if( iTop != m_iTopOld )
      {
         // keeps tracking of the top index changes
         m_iTopOld = iTop;

         // process scrolling
         ...
      }
   }

   HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);
   return hbr;
}
使用这种方法可以不必为了实现这个功能而去产生一个继承类.