title: Any idea on how to sort a CompositeCollection?
body: <p>I have a CompositeCollection that consists of ObservableCollections of two types: Companies and Contacts.
  Contact has a property FullName while Company has a property Name.</p>
  
  <p>I want to apply sorting so the collections are mixed by their types but sorted by their name, example:</p>
  
  <p>Itzhak Perlman<br>
  John Doe<br>
  Microsoft<br>
  Sarah Moore<br>
  StackOverflow<br>
  Walter Richardson  </p>
  
  <p>Note that I bound the ItemsControl to a CollectionViewSource that its Source is set the CompositeCollection, it's view becomes a CompositeCollectionView, it's an internal type, if I explicitly set its type to ListCollectionView, it only contains the CollectionContainers as its items.</p>
  
  <p>Desired solution is a workaround to enable sorting, filtering and grouping on a CompositeCollections, I don't care to override and create my own CompositeCollection, I just don't know how I can override this and enable its functionality in xaml.</p>