// Additional widget for CEP Window operator parameter
 private Widget getOperatorExtension() {
   parametersContainer.setStylePrimaryName(GuidedRuleEditorResources.INSTANCE.css().container());
   return parametersContainer;
 }
 public CEPWindowOperatorsDropdown() {
   windowContainer.setStylePrimaryName(GuidedRuleEditorResources.INSTANCE.css().container());
   initWidget(windowContainer);
 }