private void OnBookmarkSelectionChanged(object sender, RoutedPropertyChangedEventArgs <object> e)
        {
            Bookmark newValue = (Bookmark)e.NewValue;

            if (newValue != null)
            {
                document.Document.Navigator.GoToBookmark(newValue);
                this.destinationRectangle = newValue.GetDestinationRectangle((int)(this.document.Page.Width * this.GlobalScale), (int)(this.document.Page.Height * this.GlobalScale), null);
            }
        }