docs: function (eventType, callback, scope) {
                  if (callback) {
                      scope = scope || this;
                      // get the list for the event
                      var list = this._eventHandlers[eventType] || (this._eventHandlers[eventType] = []);
                      // and push the callback function
                      if (callback instanceof EventDispatcher.EventHandler) {
                          list.push(callback);
                      } else {
                          list.push(new EventDispatcher.EventHandler(callback, scope));
                      }
                  } else {
                      this.log('no eventHandler for "' + eventType + '"', "warn");
                  }
  
                  return this;
              }