event-base.js
function(customEvent, callback, context, filter, prepend) {
            return this._addMultiSubs(true, customEvent, callback, context, filter, prepend);
        }
function(customEvent, callback, context, filter, prepend) {
            return this._addMultiSubs(true, customEvent, callback, context, filter, prepend);
        }
function ( customEvent , callback , context , filter , prepend ) { return this . _addMultiSubs ( true , customEvent , callback , context , filter , prepend ) ; }
Subscribes to a customEvent. The callback will be executed `before` the defaultFn.

@static
@method before
@param customEvent {String|Array} the custom-event (or Array of events) to subscribe to. CustomEvents should
have the syntax: `emitterName:eventName`. Wildcard `*` may be used for both `emitterName` as well as `eventName`.
If `emitterName` is not defined, `UI` is assumed.
@param callback {Function} subscriber:will be invoked when the event occurs. An `eventobject` will be passed
as its only argument.
@param [context] {Object} the instance that subscribes to the event.
any object can passed through, even those are not extended with event-listener methods.
Note: Objects who are extended with listener-methods should use instance.before() instead.
@param [filter] {String|Function} to filter the event.
Use a String if you want to filter DOM-events by a `selector`
Use a function if you want to filter by any other means. If the function returns a trully value, the
subscriber gets invoked. The function gets the `eventobject` as its only argument and the context is
the subscriber.
@param [prepend=false] {Boolean} whether the subscriber should be the first in the list of before-subscribers.
@return {Object} handler with a `detach()`-method which can be used to detach the subscriber
@since 0.0.1
Subscribes to a customEvent . The callback will be executed before the defaultFn .