C# winform无边框窗体移动

    public partial class MessageHints : Form
    {
        //窗体移动API
        [DllImport("user32.dll")]
        public static extern bool ReleaseCapture();
        [DllImport("user32.dll")]
        public static extern bool SendMessage(IntPtr hwnd, int wMsg, int wParam, int IParam);
        public const int WM_SYSCOMMAND = 0x0112;
        public const int SC_MOVE = 0xF010;
        public const int HTCAPTION = 0x0002;
        [DllImport("user32")]
        private static extern int SendMessage(IntPtr hwnd, int wMsg, int wParam, IntPtr lParam);
        private const int WM_SETREDRAW = 0xB;
        public MessageHints()
        {
            InitializeComponent();
        }

1.窗体的最上面加上这一部分

 private void labelX1_MouseDown(object sender, MouseEventArgs e)
        {
            if (this.WindowState == FormWindowState.Normal)
            {
                ReleaseCapture();
                SendMessage(this.Handle, WM_SYSCOMMAND, SC_MOVE + HTCAPTION, );
            }
        }

2.事件中调取