code: @Override
      public void notifyHandlableAdded(Featurable featurable)
      {
          if (featurable.hasFeature(Refreshable.class))
          {
              final Refreshable refreshable = featurable.getFeature(Refreshable.class);
              final Integer layer = getLayer(featurable);
              final Collection<Refreshable> refreshables = getLayer(layer);
              refreshables.add(refreshable);
              indexs.add(layer);
          }
      }
docs: /*
  HandlerListener