code: public void selectByIndex(int index) {
          getDispatcher().beforeSelect(this, index);
          
          new Select(getElement()).selectByIndex(index);
          if (Config.getBoolConfigProperty(ConfigProperty.ENABLE_GUI_LOGGING)) {
              logUIActions(UIActions.SELECTED, Integer.toString(index));
          }
          
          getDispatcher().afterSelect(this, index);
      }
docs: Select the option at the given index. This is done by examing the "index" attribute of an element, and not merely
  by counting.
  
  @param index
  the index to select