private void mouse_down(object sender, MouseEventArgs e)
{
Control ctrl = sender as Control;
UnsafeNativeMethods2.ReleaseCapture(ctrl.Handle);
this.Drag(); // put the form into drag mode.
}
public void Drag()
{
UnsafeNativeMethods2.DefWindowProc(this.Handle, UnsafeNativeMethods2.WM_SYSCOMMAND, (IntPtr)UnsafeNativeMethods2.MOUSE_MOVE, IntPtr.Zero);
}