private void RewindablePositionDecremented(object sender, PositionChangedEventArgs e)
 {
     if (PositionDecremented != null)
     {
         PositionDecremented(this, e);
     }
 }
 private void RewindablePositionDecremented(object sender, PositionChangedEventArgs e)
 {
     _relativePosition -= e.Delta;
 }