title: TextBlock binding displays class name instead of empty string
body: <p>I have the following Windows RT app. I bind a List of Strings to an ItemsControl of TextBlocks. This will display the empty strings as "System.Collections.Generic.List'1[System.String]" instead of just an empty string. I would like it to display an empty string instead of the type of the DataContext. </p>
  
  <p>code behind:</p>
  
  <pre><code>public sealed partial class MainPage : Page
  {
      public MainPage()
      {
          this.InitializeComponent();
          DataContext = new List&lt;string&gt;() { "", "not empty string" };
      }
  }
  </code></pre>
  
  <p>xaml:</p>
  
  <pre><code>&lt;Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}"&gt;
      &lt;ItemsControl ItemsSource="{Binding}"&gt;
          &lt;ItemsControl.ItemsPanel&gt;
              &lt;ItemsPanelTemplate&gt;
                  &lt;StackPanel Orientation="Vertical"/&gt;
              &lt;/ItemsPanelTemplate&gt;
          &lt;/ItemsControl.ItemsPanel&gt;
          &lt;ItemsControl.ItemTemplate&gt;
              &lt;DataTemplate&gt;
                  &lt;TextBlock Text="{Binding}" FontSize="25"/&gt;
              &lt;/DataTemplate&gt;
          &lt;/ItemsControl.ItemTemplate&gt;
      &lt;/ItemsControl&gt;
  &lt;/Grid&gt;
  </code></pre>
  
  <p>output:</p>
  
  <pre><code>System.Collections.Generic.List'1[System.String]
  non empty string
  </code></pre>
  
  <p>I made the same example with traditional wpf and it displays the empty strings correctly.</p>
  
  <p><strong>Edit</strong>
  This outputs the same thing.</p>
  
  <p>code behind:</p>
  
  <pre><code>public class Model
  {
      private readonly List&lt;string&gt; items = new List&lt;string&gt;() { "", "non empty string" };
  
      public List&lt;string&gt; Items
      {
          get { return items; }
      } 
  }
  
  public sealed partial class MainPage : Page
  {
      public MainPage()
      {
          this.InitializeComponent();
          DataContext = new Model();
      }
  }
  </code></pre>
  
  <p>xaml:</p>
  
  <pre><code>&lt;Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}"&gt;
      &lt;ItemsControl ItemsSource="{Binding Path=Items}"&gt;
          &lt;ItemsControl.ItemsPanel&gt;
              &lt;ItemsPanelTemplate&gt;
                  &lt;StackPanel Orientation="Vertical"/&gt;
              &lt;/ItemsPanelTemplate&gt;
          &lt;/ItemsControl.ItemsPanel&gt;
          &lt;ItemsControl.ItemTemplate&gt;
              &lt;DataTemplate&gt;
                  &lt;TextBlock Text="{Binding}" FontSize="25"/&gt;
              &lt;/DataTemplate&gt;
          &lt;/ItemsControl.ItemTemplate&gt;
      &lt;/ItemsControl&gt;
  &lt;/Grid&gt;
  </code></pre>