private void ButtonControl_Clicked(Object src, EventArgs evt)
 {
     if (TimerUI.Enabled)
     {
         TimerUI.Stop();
         ButtonControl.Text      = "Start!";
         ButtonControl.BackColor = Color.Green;
     }
     else
     {
         TimerUI.Start();
         ButtonControl.Text      = "Stop!";
         ButtonControl.BackColor = Color.Red;
     }
 }