public void elementChanged(ElementChangedEvent event) {
   if (processDelta(event.getDelta())) {
     OpenTypeHistory.getInstance().markAsInconsistent();
   }
 }
 protected IStatus run(IProgressMonitor monitor) {
   OpenTypeHistory history = OpenTypeHistory.getInstance();
   history.internalCheckConsistency(monitor);
   return Status.OK_STATUS;
 }