C# WInForm 无框窗体移动 调用API

using System.Runtime.InteropServices;

    [DllImport("user32.dll")]
     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; 

//在空间的_MouseDown中加入如下代码:


    private void Form1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
   {
    ReleaseCapture();
    SendMessage(this.Handle, WM_SYSCOMMAND, SC_MOVE + HTCAPTION, 0);
   }