Change Node color upon selection

What would be the best way to controll the color of a GoObject when it’s being selected?

As with many “event-handling” situations, you can put the code either in a GoView event handler or in an override of a GoObject method.
The former would be GoView.ObjectGotSelection and ObjectLostSelection.
The latter would be GoObject.OnGotSelection and OnLostSelection. By default GoObject.OnGotSelection calls GoObject.AddSelectionHandles and OnLostSelection calls RemoveSelectionHandles, on the GoObject.SelectionObject.