如何创建自动滚动FlowDocumentScrollViewer的附加行为

using System.Windows;
using System.Windows.Controls;

namespace YourNamespace
{
    public static class AutoScrollBehavior
    {
        public static readonly DependencyProperty IsEnabledProperty =
            DependencyProperty.RegisterAttached("IsEnabled", typeof(bool), typeof(AutoScrollBehavior), new PropertyMetadata(false, OnIsEnabledChanged));

        public static bool GetIsEnabled(DependencyObject obj)
        {
            return (bool)obj.GetValue(IsEnabledProperty);
        }

        public static void SetIsEnabled(DependencyObject obj, bool value)
        {
            obj.SetValue(IsEnabledProperty, value);
        }

        private static void OnIsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (d is FlowDocumentScrollViewer scrollViewer)
            {
                if ((bool)e.NewValue)
                {
                    scrollViewer.Loaded += ScrollViewer_Loaded;
                }
                else
                {
                    scrollViewer.Loaded -= ScrollViewer_Loaded;
                }
            }
        }

        private static void ScrollViewer_Loaded(object sender, RoutedEventArgs e)
        {
            if (sender is FlowDocumentScrollViewer scrollViewer)
            {
                scrollViewer.ScrollChanged += ScrollViewer_ScrollChanged;
            }
        }

        private static void ScrollViewer_ScrollChanged(object sender, ScrollChangedEventArgs e)
        {
            if (sender is FlowDocumentScrollViewer scrollViewer && GetIsEnabled(scrollViewer))
            {
                scrollViewer.ScrollToVerticalOffset(scrollViewer.ExtentHeight);
            }
        }
    }
}

<FlowDocumentScrollViewer local:AutoScrollBehavior.IsEnabled="True">
    <!-- FlowDocument content here -->
</FlowDocumentScrollViewer>