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","","asdasdasd"};
             this.DataContext = list;
         }
 
         private void Button_Click(object sender, RoutedEventArgs e)
         {
             int addNumber = new Random().Next();
             list.Add(addNumber.ToString());
         }
 
         private void Button_Click_Remove(object sender, RoutedEventArgs e)
         {
             if (list.Count > )
                 list.RemoveAt();
         }
     }
 }

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