title: WPF - How to implement INotifyPropertyChanged when Properties are dynamic
body: <p>I have a business object that implements a collection of PropertyObjects.  </p>
  
  <p>BusinessObject
     SomeCollection
         Property1Object (Name=Height)
         Property2Object (Name=Width)</p>
  
  <p>Currently, I am setting the DataContext of UserControl to be the BusinessObject.  I've found that I CAN reference into the collection in the binding with something like this, say in a textBox..</p>
  
  <p>UserControl.DataContext = BusinessObject
  UserControl.TextBlock
        <strong>Text="{Binding Collection[Height].Value}"</strong></p>
  
  <p>Now, at what level can I properly implement INotifyPropertyChanged, even though at the higher level it isn't a property at all.  </p>
  
  <p>It's easy enough to see and raise the at the lowest level, the PropertyObject, but is that enough for the binding to work? </p>
  
  <p>Thanks,
  jeff</p>