function _fireCallback(callback, e, combo, sequence) {

            // if this event should not happen stop here
            if (self.stopCallback(e, e.target || e.srcElement, combo, sequence)) {
                return;
            }

            if (callback(e, combo) === false) {
                _preventDefault(e);
                _stopPropagation(e);
            }
        }
actually calls the callback function

if your callback function returns false this will use the jquery
convention - prevent default and stop propogation on the event

@param {Function} callback
@param {Event} e
@returns void