private void UpdateComboBox()
 {
     comboBox.Items.Clear();
     for (int i = 0; i < systemCircle.Count; i++)
     {
         comboBox.Items.Add("Circle " + (i + 1));
     }
     if (systemCircle.Count > 0)
     {
         comboBox.SelectedIndex = 0;
         currentCircle          = systemCircle.GetCircle(0);
     }
     else
     {
         currentCircle = null;
     }
     UpdateCircles();
 }
 public void Clear()
 {
     if (!Play)
     {
         while (SystemCircle.Count > 0)
         {
             SystemCircle.RemoveCircle(SystemCircle.GetCircle(0));
         }
         lastTrail = null;
         GC.Collect();
     }
 }