code: @Override
      public void link(NGScope scope, JQElement element, JSON attrs) {
          IsWidget widget = scope.get(getName());
          String id = "gwt-widget-" + counter++;
          element.attr("id", id);
          RootPanel.get(id).add(widget);
      }
docs: Replaces the element body with the GWT widget passed via gwt-widget
  attribute. GWT widget must implement IsWidget interface.