如何从另一个WPF窗口更新列表

public partial class MainWindow : Window
{
    public ObservableCollection<string> DataList { get; set; }

    public MainWindow()
    {
        InitializeComponent();
        DataList = new ObservableCollection<string>();
        DataContext = this;
    }

    private void OpenSecondWindowButton_Click(object sender, RoutedEventArgs e)
    {
        SecondWindow secondWindow = new SecondWindow(this);
        secondWindow.Show();
    }
}

<Window x:Class="WpfApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <ListBox ItemsSource="{Binding DataList}" />
        <Button Content="Open Second Window" Click="OpenSecondWindowButton_Click" />
    </Grid>
</Window>

public partial class SecondWindow : Window
{
    private MainWindow _mainWindow;

    public SecondWindow(MainWindow mainWindow)
    {
        InitializeComponent();
        _mainWindow = mainWindow;
    }

    private void UpdateListButton_Click(object sender, RoutedEventArgs e)
    {
        _mainWindow.DataList.Add("New Item");
    }
}

<Window x:Class="WpfApp.SecondWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="SecondWindow" Height="450" Width="800">
    <Grid>
        <Button Content="Update List" Click="UpdateListButton_Click" />
    </Grid>
</Window>