private void CaptionBinding(AnnotationLabel annotationLabel)
        {
            var binding = new Binding(nameof(Caption))
            {
                Source = this,
                Mode   = BindingMode.TwoWay
            };

            annotationLabel.SetBinding(AnnotationLabel.TextProperty, binding);
        }
        protected override void OnAnnotationLoaded(object sender, RoutedEventArgs e)
        {
            var annotationLabel = new AnnotationLabel
            {
                LabelPlacement = LabelPlacement.Top,
                CanEditText    = true
            };

            CaptionBinding(annotationLabel);
            AnnotationLabels.Add(annotationLabel);

            X1 = null;

            Y1Binding();

            pd.AddValueChanged(this, OnValueChanged);

            base.OnAnnotationLoaded(sender, e);
        }