public Object execute(final ExecutionEvent event) throws ExecutionException {
   // assumes there is only one application node
   final IApplicationNode applicationNode = ApplicationNodeManager.getApplicationNode();
   final List<ISubApplicationNode> children = applicationNode.getChildren();
   final INavigationNode<?>[] nodes = children.toArray(new ISubApplicationNode[children.size()]);
   final INavigationNode<?> nextNode =
       toNext ? findNextNode(nodes) : findPreviousNode(nodes, true);
   if (nextNode != null) {
     nextNode.activate();
   }
   return null;
 }
 private IStatuslineUIProcessRidget getStatuslineUIProcessRidget() {
   final IApplicationNode appNode = ApplicationNodeManager.getApplicationNode();
   if (appNode != null) {
     final INavigationNodeController navigationNodeController =
         appNode.getNavigationNodeController();
     if (navigationNodeController != null
         && navigationNodeController instanceof ApplicationController) {
       return ((ApplicationController) navigationNodeController)
           .getStatusline()
           .getStatuslineUIProcessRidget();
     } else {
       LOGGER.log(
           LogService.LOG_ERROR, "Unexpected: navigation node controller == null"); // $NON-NLS-1$
     }
   } else {
     LOGGER.log(LogService.LOG_ERROR, "Unexpected: appNode == null"); // $NON-NLS-1$
   }
   return null;
 }