private void timer1_Tick(object sender, EventArgs e)
        {
            if (Interlocked.Exchange(ref inTimerCallback, 1) != 0)
            {
                return;
            }

            Eye.Refresh();

            timer1.Interval = random.Next(500, 1000);

            Interlocked.Exchange(ref this.inTimerCallback, 0);
        }