Allows assigning a particular thread for event dispatching, this allows a listener to "request" that events be delivered on a particular thread thus preventing issues between conflicting properties. E.g. Swing related listeners would want to use the Swing EDT for all dispatching of events related to GUI, however ORM related events should usually be on a separate thread dedicated for persistance.
Normally this is invisible to the user and the common defaults should work for most applications. The usage of this package is when you have a business requirement for a specific thread and cannot use the default EDT/ORM threads.