WinForm 禁止拖动窗体

using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        protected override void WndProc(ref Message m)
        {
            if (m.Msg == 0xA1 && m.WParam.ToInt32() == 2)
                return;
            base.WndProc(ref m);
        }
    }
}