Thank you Eric. That does appear to work.
However, moving the custom object to the client defeats the purpose I had in mind for using the object in the first place. I had created some methods that aided a particular application's responsiveness by reducing the network traffic to the workstation. I suppose I can make it into a standalone class, but I really liked the idea of extending the grid's properties and having PxPlus manage the life of the class with the graphical control.