public override void OriginalWndProc(ref Message msg)
{
#if __MonoCS__
// When handling a left mouse button down event, save the original scroll position.
if (msg.Msg == (int)Win32.WinMsgs.WM_LBUTTONDOWN)
m_ptScrollPos = AutoScrollPosition;
#endif
base.OriginalWndProc(ref msg);
}