程序代码：

private const int WM_NCHITTEST = 0x84;
        private const int HTCLIENT = 0x1;
        private const int HTCAPTION = 0x2;

        protected override void WndProc(ref   Message m)
        {
            switch (m.Msg)
            {
                case WM_NCHITTEST:
                    base.WndProc(ref   m);
                    if ((int)m.Result == HTCAPTION)
                        m.Result = (IntPtr)HTCLIENT;
                    return;
            }
            base.WndProc(ref   m);
        }