*/
public String appendSharedDataForKey(String id_key, String key, String value) {
HttpServletRequest request = WebContextFactory.get().getHttpServletRequest();
Messages localizedMessages = LocaleHandler.localizeMessages(request);
IPersistenceManager persistenceManager = PersistenceManagerFactory.getPersistenceManager();
IWidgetInstance widgetInstance = persistenceManager.findWidgetInstanceByIdKey(id_key);
if(widgetInstance == null) return localizedMessages.getString("WidgetAPIImpl.0");
if(widgetInstance.isLocked()) return localizedMessages.getString("WidgetAPIImpl.2");
//
PropertiesController.updateSharedDataEntry(widgetInstance, key, value, true);
Notifier.notifySiblings(widgetInstance);