I have a WPF dialog that is bound to a list of `ObservableCollection<MyEntity>` type. In the dialog, I want the "OK" button to be enabled only if changes are made to the `ObservableCollection<MyEntity>` list - that includes adding/removing items from the list and modifying the individual items in the list.

For adding/removing items from the list, it is easy - I implemented a handler for the `CollectionChanged` event.

What I don't know how to do is when an individual item is modified. Say, MyEntity.Name="New Value", what interface does MyEntity class need to implement to make it 'observable'?