如何正确地允许在WPF中拖放n？

// XAML中的源元素
<ListBox x:Name="sourceListBox" AllowDrop="True" PreviewMouseLeftButtonDown="SourceListBox_PreviewMouseLeftButtonDown">
    <ListBoxItem>Item 1</ListBoxItem>
    <ListBoxItem>Item 2</ListBoxItem>
    <ListBoxItem>Item 3</ListBoxItem>
</ListBox>

// XAML中的目标元素
<ListBox x:Name="targetListBox" AllowDrop="True" PreviewDragEnter="TargetListBox_PreviewDragEnter" PreviewDragOver="TargetListBox_PreviewDragOver" PreviewDrop="TargetListBox_PreviewDrop">
    <ListBoxItem>Drop here</ListBoxItem>
</ListBox>

// 源元素的PreviewMouseLeftButtonDown事件处理程序
private void SourceListBox_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    ListBoxItem draggedItem = e.Source as ListBoxItem;
    if (draggedItem != null)
    {
        DragDrop.DoDragDrop(draggedItem, draggedItem.Content, DragDropEffects.Move);
    }
}

// 目标元素的PreviewDragEnter事件处理程序
private void TargetListBox_PreviewDragEnter(object sender, DragEventArgs e)
{
    if (!e.Data.GetDataPresent(DataFormats.StringFormat) || sender == e.Source)
    {
        e.Effects = DragDropEffects.None;
    }
}

// 目标元素的PreviewDragOver事件处理程序
private void TargetListBox_PreviewDragOver(object sender, DragEventArgs e)
{
    if (!e.Data.GetDataPresent(DataFormats.StringFormat) || sender == e.Source)
    {
        e.Effects = DragDropEffects.None;
    }
}

// 目标元素的PreviewDrop事件处理程序
private void TargetListBox_PreviewDrop(object sender, DragEventArgs e)
{
    if (e.Data.GetDataPresent(DataFormats.StringFormat))
    {
        string droppedData = e.Data.GetData(DataFormats.StringFormat) as string;
        if (droppedData != null)
        {
            ListBoxItem newItem = new ListBoxItem();
            newItem.Content = droppedData;
            targetListBox.Items.Add(newItem);
        }
    }
}