private void revalidate() {
    if (eventSource.isPaginated() == false) {
      setEnabled(false);
      return;
    }
    if (eventSource.getPageNumber() <= 1) {
      setEnabled(false);
      return;
    }

    setEnabled(true);
  }
 public boolean initialize(final SwingGuiContext context) {
   super.initialize(context);
   resources =
       new ResourceBundleSupport(
           context.getLocale(),
           SwingPreviewModule.BUNDLE_NAME,
           ObjectUtilities.getClassLoader(SwingPreviewModule.class));
   eventSource = context.getEventSource();
   eventSource.addPropertyChangeListener(updateListener);
   revalidate();
   return true;
 }