using System.Runtime.InteropServices;
 
[DllImport("user32.dll")]
static extern int ReleaseCapture();
[DllImport("user32.dll", EntryPoint = "SendMessageA")]
static extern int SendMessage(int hwnd, int wMsg, int wParam, object lParam);
private const int WM_NCLBUTTONDOWN = 161;
private void Form1_MouseDown(object sender, MouseEventArgs e)
pre>{ ReleaseCapture(); SendMessage(this.Handle.ToInt32(), WM_NCLBUTTONDOWN, 2, 0); }