WrapperCoreEvents are used to notify the listener of the internal
workings of the Wrapper.
WARNING - Great care should be taken when receiving events of this type.
They are sent from within the Wrapper's internal timing thread. If the
listner takes too much time working with the event, Wrapper performance
could be adversely affected. If unsure, it is recommended that events
of this type not be included.
Tanuki Software Development Team <email@example.com>
Returns a set of event flags for which the event should be fired.
This value is compared with the mask supplied when when a
WrapperEventListener is registered to decide which listeners should
receive the event.
If subclassed, the return value of the super class should usually
be ORed with any additional flags.