Windows Api 实现窗体拖动

        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern bool ReleaseCapture();

        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern bool SendMessage(IntPtr hwnd, int wMsg, int wParam, int lParam);

        public const int WM_SYSCOMMAND = 0x0112;
        public const int SC_MOVE = 0xF010;
        public const int HTCAPTION = 0x0002;

        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            try
            {
                ReleaseCapture();
                SendMessage(this.Handle, WM_SYSCOMMAND, SC_MOVE + HTCAPTION, 0);
            }
            catch
            {
            }
        }  

另外一种方法:

  protected override void WndProc(ref Message m)
        {
            if (m.Msg == 163 && this.ClientRectangle.Contains(this.PointToClient(new Point(m.LParam.ToInt32()))) && m.WParam.ToInt32() == 2)
                m.WParam = (IntPtr)1;
            base.WndProc(ref m);
            if (m.Msg == 132 && m.Result.ToInt32() == 1)
                m.Result = (IntPtr)2;
        }