New Post: propertyGrid show items for expanded collection

How, do I display a ObservableCollection<> of custom objects in the PropertyGrid, in which each List Item can be expanded to display the custom objects properties. (ie:

----PropertyGrid-----

CoreClass

• CoreClass Property1
  
• (+/-) ObservableCollection< CustomClass >
  
  • (+/-) CustomClass.Object1
    
    • Property1: Value
      
    • Property2: Value
      
    • …
      
    • PropertyN: Value
      
  • (+/-) CustomClass.Object2
    
    • Property1: Value
      
    • Property2: Value
      
    • …
      
    • PropertyN: Value
      

If I use [ExpandableObject] on the ObservableCollection<> it only shows the Counts property.