WPF中Expander与ListBox(ItemsControl)嵌套中的问题

1. 当ListBox放在Expander中时，为了要实现实时更新数据的效果，这里使用了

   ObservableCollection类型来作为数据源，

        初始的简单例子如下：只有一个ListBox

           xaml文件

<Window x:Class="ObservableCollectionAddRemoveDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <ListBox BorderBrush="Red" BorderThickness="2" HorizontalAlignment="Left" Height="Auto" Margin="37,32,0,0" VerticalAlignment="Top" Width="157" ItemsSource="{Binding}">
            <ListBox.ItemContainerStyle>
                <Style TargetType="ListBoxItem" >
                    <Setter Property="Opacity" Value="0.5" />
                    <Setter Property="Opacity" Value="0.5" />
                    <Setter Property="MaxHeight" Value="75" />
                    <Setter Property="Background" Value="Green"/>
                    <Style.Triggers>
                        <Trigger Property="IsSelected" Value="True">
                            <Setter Property="Opacity" Value="1.0" />
                        </Trigger>
                    </Style.Triggers>
                </Style>
            </ListBox.ItemContainerStyle>
        </ListBox>
        <ItemsControl HorizontalAlignment="Left" Height="auto" Margin="210,32,0,0" VerticalAlignment="Top" Width="157" ItemsSource="{Binding}">
            <ItemsControl.ItemContainerStyle>
                <Style TargetType="ContentPresenter">
                    <Setter Property="Opacity" Value="0.5" />
                    <Setter Property="Opacity" Value="0.5" />
                    <Setter Property="MaxHeight" Value="75" />
                </Style>
            </ItemsControl.ItemContainerStyle>
        </ItemsControl>
        <Button Content="Add" HorizontalAlignment="Left" Margin="398,65,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click"/>
        <Button Content="Remove" HorizontalAlignment="Left" Margin="398,160,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click_Remove"/>

    </Grid>
</Window>

           后台文件

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace ObservableCollectionAddRemoveDemo
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public ObservableCollection<String> list;
        //public List<String> list;
        public MainWindow()
        {
            InitializeComponent();
            list = new ObservableCollection<string>() { "asda","12asdas","a22321","asda112323","xcvcvcxv","aasda","123123","asdasdasd"};
            this.DataContext = list;
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            int addNumber = new Random().Next(999);
            list.Add(addNumber.ToString());
        }


        private void Button_Click_Remove(object sender, RoutedEventArgs e)
        {
            if (list.Count > 0)
                list.RemoveAt(0);
        }
    }
}

      发现代码实现的很顺畅，无论是增删都能实时响应到界面中

2. 但当在ListBox外面套一个Expander时，问题就出现了，如下图：

    

     在删除数据时，内容明显变少了，但属于删掉内容的位置确仍然保留在界面上！！！

     解决的办法是：在Expander的 ContentPresenter外面套一个StackPanel，如下：

 <StackPanel>
         <ContentPresenter x:Name="ExpanderContent" ContentSource="Content"/>
</StackPanel>

===========================================

     当将Expander放在ListBox中时也有可能会出现类似的问题：https://www.dotblogs.com.tw/ouch1978/archive/2011/03/11/wpf-expander-in-listbox.aspx