The behavior of an object in the Workplace Shell is very similar to that of a window under Presentation Manager. An object must have its class registered with the system, an instance of that class must be created ("instantiated") in the system, and that instance (and any other instance) then receives messages and uses its methods to process these messages. When processing is completed, the instance may be destroyed.
One significant difference between a Workplace Shell object class and a window class under Presentation Manager is that Workplace Shell object classes are normally persistent; that is, while a Presentation Manager window class is defined only for the duration of the application's execution, a Workplace Shell object class remains defined to the system, and is useable by any application until such time as it is explicitly deregistered from the system.