Form Mover

using System.Runtime.InteropServices;

[DllImportAttribute("user32.dll")]
public static extern int SendMessage(IntPtr hWnd,
                 int Msg, int wParam, int lParam);
[DllImportAttribute("user32.dll")]
public static extern bool ReleaseCapture();

private void Form1_MouseDown(object sender,
        System.Windows.Forms.MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        ReleaseCapture();
        SendMessage(Handle, 0xA1, 0x2, 0);
    }
}