Use the RegisterChanges method to have an object notified whenever changes occur in the image list. The TChangeLink's OnChange event is called whenever a change in the image list occurs. 

Create a change link object for each object that should be notified of changes. Register each object by calling RegisterChanges and passing its change link object as the Value parameter. The OnChange event of all registered change link objects is then triggered when a change occurs in the image list. Any code assigned to the OnChange event handlers will execute. 

UnRegisterChanges 

OnChange