title: Correct property name for nested property and INotifyDataErrorInfo
body: <p>I'm using the INotifyDataError interface for async validation in WPF. I have a property</p>
  
  <pre><code>&lt;TextBox Grid.Column="5" 
           Text="{Binding XXX.Name, ValidatesOnNotifyDataErrors=True}"/&gt;
  </code></pre>
  
  <p>On my view model  I have a property</p>
  
  <pre><code>public SomeType XXX
  </code></pre>
  
  <p>and on the type SomeType I have the property</p>
  
  <pre><code>public string Name
  </code></pre>
  
  <p>now my ViewModel implements INotifyPropertyChanged and INotifyDataError and validation is done asynchronously in my viewmodel class. SomeType only implements INotifyPropertyChanged.</p>
  
  <p>My questions is this. When I raise <code>ErrorsChanged</code> event with <code>DataErrorsChangedEventArgs(propertyName))</code> what should the propertyName be. Note my Binding path is <code>XXX.Name</code>. Should propertyName be</p>
  
  <ul>
  <li>XXX.Name</li>
  <li>Name</li>
  </ul>
  
  <p>or something else or do I have to implement INotifyDataErrorInfo in my <code>SomeType</code> class as well which I was hoping not to have to do as I want my validation to stay in the main view model.</p>
  
  <p>Anyway I've tried both above and the textbox is not getting a red box around it though I can verify that the error event is being raised.</p>