1    private const int WM_NCLBUTTONDOWN = 0XA1;   //.定义鼠標左鍵按下
2    private const int HTCAPTION     = 2;

1 private void Form1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
2    {   
3     //為當前的應用程序釋放鼠標鋪獲
4     ReleaseCapture();
5     //發送消息﹐讓系統誤以為在标题栏上按下鼠標
6     SendMessage((int)this.Handle,WM_NCLBUTTONDOWN,HTCAPTION,0);
7    }

1    [DllImport("user32.dll",EntryPoint="SendMessageA")]
2    private static extern int SendMessage(int hwnd,int wMsg,int wParam,int lParam);
3 
4    [DllImport("user32.dll")]
5    private static extern int ReleaseCapture();

1 private bool isMouseDown = false;
2 private Point FormLocation;     //form的location
3 private Point mouseOffset;      //鼠标的按下位置

1 private void Form1_MouseDown(object sender, MouseEventArgs e)
2 {
3     if (e.Button == MouseButtons.Left)
4     {
5         isMouseDown = true;
6         FormLocation = this.Location;
7         mouseOffset = Control.MousePosition;
8     }
9 }

1 private void Form1_MouseUp(object sender, MouseEventArgs e)
2 {
3     isMouseDown = false;
4 }

 1 private void Form1_MouseMove(object sender, MouseEventArgs e)
 2 {
 3     int _x = 0;
 4     int _y = 0;
 5     if (isMouseDown)
 6     {
 7         Point pt = Control.MousePosition;
 8         _x = mouseOffset.X - pt.X;
 9         _y = mouseOffset.Y - pt.Y;
10 
11         this.Location = new Point(FormLocation.X - _x, FormLocation.Y - _y);
12     }
13 }