State st = controller.currentState();
// Chose a preemptive transition, if there is one,
// and execute its choice actions.
// The choice actions are the outputActions, not the setActions.
Transition tr = controller.chooseTransition(st
.preemptiveTransitionList());
_enabledTransition = tr;
// If a preemptive transition was found, prefire and fire
// the refinements of the transition, and then return.