(转)让鼠标拖动WinForm窗体，模仿鼠标标题栏拖动

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

       private const int WM_SYSCOMMAND = 0x0112;//点击窗口左上角那个图标时的系统信息  
        private const int WM_MOVING = 0x216;//鼠标移动消息  
        private const int SC_MOVE = 0xF010;//移动信息  
        private const int HTCAPTION = 0x0002;//表示鼠标在窗口标题栏时的系统信息  
        private const int WM_NCHITTEST = 0x84;//鼠标在窗体客户区（除了标题栏和边框以外的部分）时发送的消息  
        private const int HTCLIENT = 0x1;//表示鼠标在窗口客户区的系统消息  
        private const int SC_MAXIMIZE = 0xF030;//最大化信息  
        private const int SC_MINIMIZE = 0xF020;//最小化信息 

        protected override void WndProc(ref Message m)
        {
            switch (m.Msg)
            {
                case WM_MOVING: //如果鼠标移                  
                    base.WndProc(ref m);//调用基类的窗口过程——WndProc方法处理这个消息
                    if (m.Result == (IntPtr)HTCLIENT)//如果返回的是HTCLIENT
                    {
                        m.Result = (IntPtr)HTCAPTION;//把它改为HTCAPTION
                        return;//直接返回退出方法
                    }
                    break;
            }
            base.WndProc(ref m);//如果不是鼠标移动或单击消息就调用基类的窗口过程进行处理
        }

        protected override void OnMouseMove(MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                ReleaseCapture();
                SendMessage(this.Handle, WM_SYSCOMMAND, SC_MOVE + HTCAPTION, 0);
            }
            base.OnMouseMove(e);
        }

原文地址:http://blog.csdn.net/qingnan/article/details/5722464