How to get notifications from nested properties in C#/WPF?

Question

I have the following property in my view model and the view is binding to this property.

All works fine except for a special case where the ActiveCategory (within the _catManager) can change from other events (outside of this view).

I don't want to expose the entire Category Manager in the view model so I'm only exposing what properties I need. What is the best way to do this so that the view gets notified of all changes, even those changes not triggered within this view model?

 
    public ICategory SelectedCategory
     {
      get
       {
        return _catManager.ActiveCategory;
       }
      set
       {
        _catManager.ActiveCategory = value;
        OnPropertyChanged("SelectedCategory");
       }
     }

Answer 1

Have your viewmodel hook into the _catManager's INotifyPropertyChanged event and have it relay the property change events through the viewmodel. When you see "ActiveCategory" come through, that means you need to raise an INPC for "SelectedCategory".

Answer 2

You need to delegate notification to whatever class _catManager is as well.

So a change to it's ActiveCategory property raises a notification.

One way would be to add a handler in the the class that has it as a property and then raise a notification that it's _catManager has changed somehow.