code: function (key, handler, obj, overrideContext) {
      
              var property = this.config[key.toLowerCase()];
      
              if (property && property.event) {
                  if (!Config.alreadySubscribed(property.event, handler, obj)) {
                      property.event.subscribe(handler, obj, overrideContext);
                  }
                  return true;
              } else {
                  return false;
              }
      
          }
docs: Subscribes an external handler to the change event for any
  given property.
  @method subscribeToConfigEvent
  @param {String} key The property name
  @param {Function} handler The handler function to use subscribe to
  the property's event
  @param {Object} obj The Object to use for scoping the event handler
  (see CustomEvent documentation)
  @param {Boolean} overrideContext Optional. If true, will override
  "this" within the handler to map to the scope Object passed into the
  method.
  @return {Boolean} True, if the subscription was successful,
  otherwise false.