Silverlight：MouseDragElementBehavior无法应用于ListBox的变相解决办法

Blend自带的行为MouseDragElementBehavior应用到ListBox后，如果用鼠标按住列表列拖动，没有任何效果，在多次尝试中意外发现，如果将ListBox的边框设置成一个较大值，在边框上点击时，却可以拖动，但是一般开发中，没人会把ListBox设置一个粗粗的难看边框。于是想到了下面的变通解决办法：当鼠标进入时显示边框，鼠标离开时再隐藏边框。

示例代码：

Xaml部分

<UserControl
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity" xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions" x:Class="sl_drag_sample.MainPage"
    mc:Ignorable="d"
    d:DesignHeight="300" d:DesignWidth="400">

    <Grid x:Name="LayoutRoot" Background="White">

        <ListBox x:Name="lbSample" MinHeight="50" MinWidth="100"  BorderThickness="0" HorizontalAlignment="Center" VerticalAlignment="Center" MouseEnter="ShowBorder"  MouseLeftButtonUp="HideBorder" MouseLeftButtonDown="ShowBorder"  MouseMove="ShowBorder" MouseLeave="HideBorder">
            <i:Interaction.Behaviors>
                <ei:MouseDragElementBehavior/>
            </i:Interaction.Behaviors>
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="这是测试文字">
                        <i:Interaction.Behaviors>
                            <ei:MouseDragElementBehavior/>
                        </i:Interaction.Behaviors>
                    </TextBlock>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</UserControl>

Xaml.cs部分

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

namespace sl_drag_sample
{
    public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();

            this.Loaded += new RoutedEventHandler(MainPage_Loaded);
        }

        void MainPage_Loaded(object sender, RoutedEventArgs e)
        {
            char[] s = "ABCDE".ToCharArray();
            lbSample.ItemsSource = s;
        }

        private void ShowBorder(object sender, MouseEventArgs e)
        {
            (sender as ListBox).BorderThickness = new Thickness(20.0);
        }

        private void HideBorder(object sender, MouseEventArgs e)
        {
            (sender as ListBox).BorderThickness = new Thickness(0.0);
        }
    }
}