title: ObservableCollection not noticing when Item in it changes (even with INotifyPropertyChanged)
body: <p>Does anyone know why this code doesn't work:</p>
  
  <pre><code>public class CollectionViewModel : ViewModelBase {  
      public ObservableCollection&lt;EntityViewModel&gt; ContentList
      {
          get { return _contentList; }
          set 
          { 
              _contentList = value; 
              RaisePropertyChanged("ContentList"); 
              //I want to be notified here when something changes..?
              //debugger doesn't stop here when IsRowChecked is toggled
          }
       }
  }
  
  public class EntityViewModel : ViewModelBase
  {
  
      private bool _isRowChecked;
  
      public bool IsRowChecked
      {
          get { return _isRowChecked; }
          set { _isRowChecked = value; RaisePropertyChanged("IsRowChecked"); }
      }
  }
  </code></pre>
  
  <p><code>ViewModelBase</code> containts everything for <code>RaisePropertyChanged</code> etc. and it's working for everything else except this problem..</p>