#region 無邊框拖動效果
    [DllImport("user32.dll")]//拖動無窗體的控件
    public static extern bool ReleaseCapture();
    [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 Start_MouseDown(object sender, MouseEventArgs e)
    {
      //拖動窗體
      ReleaseCapture();
      SendMessage(this.Handle, WM_SYSCOMMAND, SC_MOVE + HTCAPTION, 0);
    }
    #endregion