La Liaison De Zone De Liste Déroulante.SelectedItem en Silverlight

C'est me rend fou. Voici le code XAML:

    <UserControl x:Class="SilverlightApplication1.Page"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <Grid x:Name="LayoutRoot" Background="White">
    <StackPanel HorizontalAlignment="Left" VerticalAlignment="Top">
      <ComboBox ItemsSource="{Binding Path=Thing.Stuff}"
                SelectedItem="{Binding Path=Thing.SelectedStuff}">
        <ComboBox.ItemTemplate>
          <DataTemplate>
            <TextBlock Text="{Binding Path=Name}" />
          </DataTemplate>
        </ComboBox.ItemTemplate>
      </ComboBox>
      <Button Content="Again" Click="Button_Click" />
    </StackPanel>
  </Grid>
</UserControl>

Et le code-behind:

using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
namespace SilverlightApplication1
{
public partial class Page : UserControl
{
public Page()
{
InitializeComponent();
Data data = new Data();
data.Thing = new Thing();
data.Thing.Stuff = new ObservableCollection<Stuff>();
data.Thing.Stuff.Add( new Stuff { Name = "Stuff 1" } );
data.Thing.Stuff.Add( new Stuff { Name = "Stuff 2" } );
data.Thing.Stuff.Add( new Stuff { Name = "Stuff 3" } );
data.Thing.SelectedStuff = data.Thing.Stuff.Last();
DataContext = data;
}
private void Button_Click( object sender, RoutedEventArgs e )
{
Data data = ( DataContext as Data );
data.Thing.Stuff.Clear();
data.Thing.Stuff.Add( new Stuff { Name = "Stuff 4" } );
data.Thing.Stuff.Add( new Stuff { Name = "Stuff 5" } );
data.Thing.Stuff.Add( new Stuff { Name = "Stuff 6" } );
data.Thing.SelectedStuff = data.Thing.Stuff.Last();
}
}
public class Data : INotifyPropertyChanged
{
private Thing _Thing;
public Thing Thing
{
get { return _Thing; }
set { _Thing = value; NotifyPropertyChanged( "Thing" ); }
}
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged( string propertyName )
{
if ( PropertyChanged == null ) { return; }
PropertyChanged( this, new PropertyChangedEventArgs( propertyName ) );
}
}
public class Thing : INotifyPropertyChanged
{
private ObservableCollection<Stuff> _Stuff;
public ObservableCollection<Stuff> Stuff
{
get { return _Stuff; }
set { _Stuff = value; NotifyPropertyChanged( "Stuff" ); }
}
private Stuff _SelectedStuff;
public Stuff SelectedStuff
{
get { return _SelectedStuff; }
set { _SelectedStuff = value; NotifyPropertyChanged( "SelectedStuff" ); }
}
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged( string propertyName )
{
if ( PropertyChanged == null ) { return; }
PropertyChanged( this, new PropertyChangedEventArgs( propertyName ) );
}
}
public class Stuff : INotifyPropertyChanged
{
private string _Name;
public string Name
{
get { return _Name; }
set { _Name = value; NotifyPropertyChanged( "Name" ); }
}
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged( string propertyName )
{
if ( PropertyChanged == null ) { return; }
PropertyChanged( this, new PropertyChangedEventArgs( propertyName ) );
}
}
}

Lorsque le chargement de la page, il y a une zone de liste déroulante avec des "Choses " 3" est sélectionné. Lorsque le bouton est cliqué, les éléments dans la zone de liste déroulante changer, mais les "Choses " 6" doit être sélectionné. Au lieu de cela, rien n'est sélectionné.