protected override void OnElementChanged(ElementChangedEventArgs <View> e)
        {
            base.OnElementChanged(e);

            if (e.NewElement == null)
            {
                return;
            }

            if (BackgroundManager == null)
            {
                BackgroundManager = new MaterialBackgroundManager(this);
            }

            UpdateIsFocusable();
        }
        protected override void Dispose(bool disposing)
        {
            if (_disposed)
            {
                return;
            }

            _disposed = true;

            if (disposing)
            {
                if (BackgroundManager != null)
                {
                    BackgroundManager.Dispose();
                    BackgroundManager = null;
                }
            }

            base.Dispose(disposing);
        }