To support this functionality, persistent properties should be implemented in a specific manner. If you implement your business model in code, use either the SetPropertyValue or OnChanged method in persistent property setters. These methods have several overloads. Use the overloads that take both the old and new property values:
If you use the Data Model Designer to create the data model, then you do not need to worry about implementing persistent properties. Designer automatically declares persistent properties in the proper manner.