protected override void OnAttachedToVisualTree(CompositeDisposable disposable)
    {
        if (AssociatedObject is null)
        {
            return;
        }

        var sharedState = new NavBarSelectedIndicatorState();

        SetParentState(AssociatedObject, sharedState);
        disposable.Add(sharedState);
    }
 public static void SetParentState(Control element, NavBarSelectedIndicatorState value)
 {
     element.SetValue(ParentStateProperty, value);
 }