/// <summary>
        /// <see cref="Source"/> PropertyChangedCallback function.
        /// </summary>
        /// <param name="d">The <see cref="TitledImage"/> control whose <see cref="Source"/> property changed.</param>
        /// <param name="e">DependencyPropertyChangedEventArgs which contains the old and new values.</param>
        private static void OnSourcePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            ItemViewerControl titledImage = d as ItemViewerControl;

            titledImage.OnSourceChanged((ImageSource)e.OldValue, (ImageSource)e.NewValue);
        }
        /// <summary>
        /// <see cref="Title"/> PropertyChangedCallback function.
        /// </summary>
        /// <param name="d">The <see cref="TitledImage"/> control whose <see cref="Title"/> property changed.</param>
        /// <param name="e">DependencyPropertyChangedEventArgs which contains the old and new values.</param>
        private static void OnNavigateUriPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            ItemViewerControl titledImage = d as ItemViewerControl;

            titledImage.OnNavigateUriChanged((string)e.OldValue, (string)e.NewValue);
        }