event-dispatch-handler in Eventspaces

This parameter (see parameters, section 7.4 in PLT MzScheme: Language Manual) gets or installs the current event dispatch handler. The event dispatch handler is called by an eventspace's handler thread for every queue-based event to be processed in the eventspace. The only argument to the handler is the eventspace in which an event should be dispatched. The event dispatch handler gives the programmer control over the timing of event dispatching, but not the order in which events are dispatched within a single eventspace.

An event dispatch handler must ultimately call the primitive event dispatch handler. If an event dispatch handler returns without calling the primitive handler, then the primitive handler is called directly by the eventspace handler thread.

• (event-dispatch-handler) -> procedure of one argument: an eventspace

  Returns the current handler.

  
  

• (event-dispatch-handler handler) -> void
     handler : procedure of one argument: an eventspace

  Sets the current handler.