title: Binding a List within a bound ObservableCollection
body: <p>In my WPF application I have an Observablecollection "CollOfPersons" of Persons, where each Person Object has a property "NotesOnPerson" of type </p>
  
  <pre><code>List&lt;Notes&gt;
  </code></pre>
  
  <p>(among other properties). Now I bind "CollOfPersons" to a listbox lb in code via </p>
  
  <pre><code>lb.ItemsSource = CollOfPersons;
  </code></pre>
  
  <p>Now I have set up a template how to display a person, namely I wrap each person in a 'Expander' and display the basic properties (e.g., Name, Age) in Expander.header, and this works fine, e.g.,</p>
  
  <pre><code>&lt;Expander.Header&gt;
    &lt;StackPanel Orientation="Horizontal"&gt;
      ...
      &lt;TextBlock Text="{Binding Path=Name}"/&gt;
      ...
    &lt;/StackPanel&gt;
  &lt;/Expander.Header&gt;
  </code></pre>
  
  <p>However, now I'd like to bind the NotesOnPerson list of notes to the Expander.Content. But since this is again a list of varying size I don't know how to do it. Same strategy as above does not work, because I don't know the name of the Expander (as I knew the name 'lb' of the big listbox in which all the stuff is). Something like</p>
  
  <pre><code>&lt;Expander.Content&gt;
     &lt;ListBox ItemTemplate="{StaticResource NoteTemplate}"
              ItemsSource="{Binding Path=NotesOnPerson}"/&gt;
  &lt;/Expander.Content&gt;
  </code></pre>
  
  <p>doesn't seem to work. I seem to be confused about code and XAML binding. How should I solve this?</p>