code: public void empty() {
  		searchButton.setDisabled(true);
  		resetButton.setDisabled(true);
  		for (AttributeCriterionPane criterionPane : criterionPanes) {
  			criterionStack.removeMember(criterionPane);
  		}
  		criterionPanes.clear();
  		for (HLayout criterionPane : buttonPanes) {
  			buttonStack.removeMember(criterionPane);
  		}
  		buttonPanes.clear();
  		for (HandlerRegistration handlerRegistration : addHandlers) {
  			handlerRegistration.removeHandler();
  		}
  		addHandlers.clear();
  		for (HandlerRegistration handlerRegistration : removeHandlers) {
  			handlerRegistration.removeHandler();
  		}
  		removeHandlers.clear();
  		addEmptyRow(0);
  	}
docs: Empty the grid, thereby removing all rows. When that is done, a new empty row will be displayed.