private static void OnLabelTextChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
        {
            LabeledContentControl labeledContentControl = o as LabeledContentControl;

            if (labeledContentControl != null)
            {
                labeledContentControl.OnLabelTextChanged((string)e.OldValue, (string)e.NewValue);
            }
        }
        private static void OnIsRequiredChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
        {
            LabeledContentControl labeledContentControl = o as LabeledContentControl;

            if (labeledContentControl != null)
            {
                labeledContentControl.OnIsRequiredChanged((bool)e.OldValue, (bool)e.NewValue);
            }
        }