private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            test();
        }

        private void test()
        {
            while (true)
            {
                ts = stopWatch.Elapsed;
                elapsedTime = string.Format("{0:00}:{1:00}:{2:00}.{3:00}", ts.Hours, ts.Minutes, ts.Seconds,
                   ts.Milliseconds / 10);
                if (InvokeRequired)
                {
                    this.Invoke(new Action(() => test()));
                }
                else
                {
                    clockLabel.Text = elapsedTime;
                }
            }