code: function(arg) {
  			return gui.TrackerPlugin.prototype._breakdown.call(this, arg).map(function(type) {
  				return type === 'transitionend' ? this._transitionend() : type;
  			}, this);
  		}
docs: Manhandle 'transitionend' event. Seems only Safari is left now...
  @param {Array<String>|String} arg
  @returns {Array<String>}