winForm无标题栏拖动窗体

        protected override void WndProc(ref Message m)
        {
            base.WndProc(ref m);
            if (m.Msg == 0x84)
            {
                switch (m.Result.ToInt32())
                {
                    case 1:
                        m.Result = new IntPtr(2);
                        break;
                }
            }
        }