protected virtual void OnGaugeChanged(AngularGauge old, AngularGauge newValue)
 {
 }
 protected override void OnVisualParentChanged(DependencyObject oldParent)
 {
     this.Gauge = this.VisualAncestors().OfType<AngularGauge>().FirstOrDefault();
     base.OnVisualParentChanged(oldParent);
 }