code: function (cfg) {
              var listeners = cfg.on;
  
              this._chainListener(listeners, "tapstart", {
                  fn : this._manageEvents,
                  scope : this
              });
  
              this._chainListener(listeners, "tapcancel", {
                  fn : this._manageEvents,
                  scope : this
              });
  
              this._chainListener(listeners, "tap", {
                  fn : this._manageEvents,
                  scope : this
              });
          }
docs: Add special listeners on top of the ones specified in configuration.
  @param {aria.touch.widgets.ButtonCfg.Properties} cfg Widget configuration.
  @protected