title: RaisePropertyChanged doesn't work for ObservableCollection
body: <p>I have a really weird problem with update UI using MVVM Light Toolkit. The RaisePropertyChanged doesn't work at all for my ObservableCollection. </p>
  
  <p>Here is the XAML code:</p>
  
  <pre><code>&lt;ListBox x:Name="list"  ItemsSource="{Binding ModelList}" SelectedItem="{Binding SelectedItem, Mode=TwoWay}"&gt;
         &lt;ListBox.ItemTemplate&gt;
             &lt;DataTemplate&gt;
                 &lt;StackPanel Orientation="Horizontal"&gt;
                     &lt;TextBlock Text="{Binding Name}"&gt;&lt;/TextBlock&gt;
                     &lt;CheckBox IsChecked="{Binding IsChecked}"&gt;&lt;/CheckBox&gt;
                 &lt;/StackPanel&gt;
             &lt;/DataTemplate&gt;
         &lt;/ListBox.ItemTemplate&gt;
         &lt;interaction:Interaction.Triggers&gt;
             &lt;interaction:EventTrigger EventName="SelectionChanged"&gt;
                  &lt;cmd:EventToCommand Command="{Binding TempCommand}" CommandParameter="{Binding ElementName=list, Path=SelectedItem}"
                                 PassEventArgsToCommand="True"/&gt;
              &lt;/interaction:EventTrigger&gt;
         &lt;/interaction:Interaction.Triggers&gt;
     &lt;/ListBox&gt;
  </code></pre>
  
  <p>And there is ViewModel code part:</p>
  
  <pre><code>private Model _selectedItem;
      public Model SelectedItem
      {
          get { return _selectedItem; }
          set
          {
              _selectedItem = value;
              RaisePropertyChanged("SelectedItem");
          }
      }
  
      private ObservableCollection&lt;Model&gt; _modelList;
      public ObservableCollection&lt;Model&gt; ModelList
      {
          get { return _modelList; }
          set
          {
              _modelList = value;
              RaisePropertyChanged("ModelList");
          }
      }
  
      public RelayCommand&lt;Model&gt; TempCommand { get; private set; }
      /// &lt;summary&gt;
      /// Initializes a new instance of the MainViewModel class.
      /// &lt;/summary&gt;
      public MainViewModel()
      {
          modelList = new ObservableCollection&lt;Model&gt;()
              {
                  new Model()
                      {
                          IsChecked = true,
                          Name = "Temp1"
                      },
                  new Model()
                      {
                          IsChecked = false,
                          Name = "Temp2"
                      },
                  new Model()
                      {
                          IsChecked = false,
                          Name = "Temp3"
                      }
              };
          ModelList = modelList;
  
          TempCommand = new RelayCommand&lt;Model&gt;(Model_SelectedItem);
      }
  
      private void Model_SelectedItem(Model item)
      {
          // What should I do here?
      }
  </code></pre>
  
  <p>When I change the ModelList - there is no reaction from ListBox UI. </p>
  
  <p>Anyone can help me ?</p>