ObservableCollection< T> WPF绑定显示未更新

在以下情况下为 Observable Collection 设置数据绑定时：使用WPF在XAML中实现CollectionChanged处理程序，所有绑定均正常运行，但我发现除了更改ListBox中ItemsSource定义的属性外，我必须使用类似于以下代码的代码手动更新UI的可视容器：

In setting up data binding for Observable Collection , under the following context: Implementing CollectionChanged Handler in XAML with WPF all bindings are working correctly, but I'm finding that in addition to changing the Property defined by ItemsSource within the ListBox, I am having to manually update the UI's visual container with code similar to:

XAML：

<Grid DataContext="{Binding ElementName=PollPublicStockMainWindow}">
        <ListBox Height="132" HorizontalAlignment="Left" Name="lbFiles" 
                 VerticalAlignment="Top" Width="167" 
                 Margin="{StaticResource ConsistemtMargins}"  
                 ItemsSource="{Binding LbItems}">
            <ListBox.InputBindings>
                <KeyBinding Key="Delete" Command="local:MainWindow.DeleteEntry"/>
            </ListBox.InputBindings>
        </ListBox>
</Grid>

CodeBehind：

CodeBehind:

public partial class MainWindow : Window 
{
    public MainWindow() 
    {
        InitializeComponent();
        LbItems = new ObservableCollection<string>();
        LbItems.CollectionChanged += lbFiles_CollectionChanged;
    }

    private void lbFiles_CollectionChanged(object sender, 
         System.Collections.Specialized.NotifyCollectionChangedEventArgs e) 
    {
        MemoryPersistentStorageBridge memBridge = GetPersistentStorageBridge;
        List<string> newFileList = new List<string>();

        foreach (string str in LbItems) {
            DoSomethingWithNewString(str); //these 2 lines are always paired?  
            lbFiles.Items.Add(str); // this should NOT be needed 
         }
    }
}

我缺少约束力吗？