code: public void onClick(MenuItemClickEvent event) {
  		final FeatureTransaction ft = mapWidget.getMapModel().getFeatureEditor().getFeatureTransaction();
  		if (ft != null) {
  			SimpleFeatureAttributeWindow window = new SimpleFeatureAttributeWindow(ft.getNewFeatures()[0]) {
  
  				public void onOk(Feature feature) {
  					// Copy the attributes to the real feature:
  					// Don't overwrite the feature itself, as the GraphicsContext expects the same object for rendering!
  					ft.getNewFeatures()[0].setAttributes(feature.getAttributes());
  				}
  
  				public void onClose() {
  				}
  			};
  			window.show();
  		}
  	}
docs: Remove an existing ring from a Polygon or MultiPolygon at a given index.
  
  @param event
  The {@link MenuItemClickEvent} from clicking the action.