拖动窗体FormBorderStyle属性为None的窗体移动

winform窗体的样式很单一，不够漂亮，往往我们需要对窗体进行重写，但是我们又要保留在重写前窗体本身带的功能，例如拖动窗体的头进行移动之类的。

一下方式可以实现该方法：

        [DllImport("user32")]
        public static extern int ReleaseCapture();
        [DllImport("user32")]
        public static extern int SendMessage(IntPtr hwnd, int msg, int wp, int lp);
        /// <summary>
        /// 是否允许移动
        /// </summary>
        bool IsMove = false;
        /// <summary>
        /// 判断鼠标是否在可移动范围内按下
        /// </summary>
        private void Form_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == System.Windows.Forms.MouseButtons.Left)
            {
                Rectangle rect = new Rectangle(1, 1, this.Width - 70, labMin.Height);   //允许拖动的矩形范围
                this.IsMove = rect.Contains(new Point(e.X, e.Y));                       //鼠标按下的点是否在允许拖动范围内
            }
        }
        /// <summary>
        /// 鼠标弹起时取消移动
        /// </summary>
        private void Form_MouseUp(object sender, MouseEventArgs e)
        {
            this.IsMove = false;
        }
        /// <summary>
        /// 移动窗体
        /// </summary>
        private void Form_MouseMove(object sender, MouseEventArgs e)
        {
            if (this.IsMove && e.Button == System.Windows.Forms.MouseButtons.Left && this.WindowState != FormWindowState.Maximized)
            {
                ReleaseCapture();
                SendMessage(Handle, 274, 61440 + 9, 0);
                return;
            }
        }