title: Bind textblock to two properties
body: <p>I have a Textblock that is bound to a property in the ItemsSource collection. I'd like to display two properties from that class in the same textblock, but it seems I can only perform one binding at a time.
  I currently have this:</p>
  
  <pre><code>Text="{Binding Title}"
  </code></pre>
  
  <p>but I want I want to append another property, so in theory it would be:</p>
  
  <pre><code>Text="{Binding Title - Author}" 
  </code></pre>
  
  <p>with the output looking like "Shakespeare - Romeo and Juliet". I've tried adding a comma, another binding and other things, but they all result in an exception being thrown (e.g. Unknown attribute Text on element TextBlock).</p>
  
  <p>Both properties comes from the same class, so I won't need to have two data sources. </p>