title: How to bind to parent DataTemplate from within an ItemsControl.ItemTemplate
body: <p>I have a container type control which contains a number of items.  The container control has a <code>DataTemplate</code> defined which also contains a <code>ItemsControl</code> with a <code>DataTemplate</code> for the item.  The items however need to bind to something from the container control.  A simplified example is given below:</p>
  
  <pre><code>&lt;DataTemplate DataType="{x:Type ContainerType}"&gt;
  
      &lt;!-- Display of the container stuff--&gt;
  
      &lt;ItemsControl ItemsSource="{Binding Items, Mode=OneWay}"&gt;
  
          &lt;ItemsControl.ItemTemplate&gt;
                &lt;DataTemplate DataType="{x:Type Item}"&gt;
  
                    &lt;!-- Display of the item stuff --&gt;
                    &lt;ComboBox Text="Choose a container-level option..."
                              ItemsSource="{WHAT GOES HERE?}"/&gt;
  
                  &lt;/DataTemplate&gt;
           &lt;/ItemsControl.ItemTemplate&gt;
  
        &lt;/ItemsControl&gt;
  &lt;/DataTemplate&gt;
  </code></pre>
  
  <p>How to I bind something at the item level back up to the container level?</p>