public/javascripts/vendor/javascripts/ember.js
function addListener(obj, eventName, target, method) {
  Ember.assert("You must pass at least an object and event name to Ember.addListener", !!obj && !!eventName);

  if (!method && 'function' === typeof target) {
    method = target;
    target = null;
  }

  var actionSet = actionSetFor(obj, eventName, target, true),
      methodGuid = guidFor(method);

  if (!actionSet[methodGuid]) {
    actionSet[methodGuid] = { target: target, method: method };
  }

  if ('function' === typeof obj.didAddListener) {
    obj.didAddListener(eventName, target, method);
  }
}
function addListener(obj, eventName, target, method) {
  Ember.assert("You must pass at least an object and event name to Ember.addListener", !!obj && !!eventName);

  if (!method && 'function' === typeof target) {
    method = target;
    target = null;
  }

  var actionSet = actionSetFor(obj, eventName, target, true),
      methodGuid = guidFor(method);

  if (!actionSet[methodGuid]) {
    actionSet[methodGuid] = { target: target, method: method };
  }

  if ('function' === typeof obj.didAddListener) {
    obj.didAddListener(eventName, target, method);
  }
}
function addListener ( obj , eventName , target , method ) { Ember . assert ( "You must pass at least an object and event name to Ember.addListener" , ! ! obj && ! ! eventName ) ; if ( ! method && 'function' === typeof target ) { method = target ; target = null ; } var actionSet = actionSetFor ( obj , eventName , target , true ) , methodGuid = guidFor ( method ) ; if ( ! actionSet [ methodGuid ] ) { actionSet [ methodGuid ] = { target : target , method : method } ; } if ( 'function' === typeof obj . didAddListener ) { obj . didAddListener ( eventName , target , method ) ; } }
The sendEvent arguments > 2 are passed to an event listener.

@memberOf Ember
The sendEvent arguments > 2 are passed to an event listener .