using System.Runtime.InteropServices;

[DllImport("user32.dll")]
        public static extern IntPtr SendMessage(IntPtr hWnd,int msg,int wparam,int lparam);
        protected override void OnMouseDown(MouseEventArgs e)
        {
            base.OnMouseDown(e);
            if (e.Button == MouseButtons.Left)//按下的是鼠標左鍵           
             {
              Capture = false;//釋放鼠標使能夠手動操作               
                SendMessage(Handle, 0x00A1, 2, 0);//拖動窗體           
             }
        }