/*
  * Implements method from IViewPart.
  */
 public void saveState(IMemento memento) {
   if (fViewer == null) {
     // part has not been created
     if (fMemento != null) // Keep the old state;
     memento.putMemento(fMemento);
     return;
   }
   if (fHasWorkingSetFilter) fWorkingSetFilterActionGroup.saveState(memento);
   if (fHasCustomFilter) fCustomFiltersActionGroup.saveState(memento);
   saveSelectionState(memento);
   saveLinkingEnabled(memento);
 }