@Override
 public void load(IMemento memento) {
   super.load(memento);
   IMemento pref = memento.getChild(PREF_ID);
   if (pref != null) {
     prefId = pref.getTextData();
   }
   IMemento lbl = memento.getChild(LABEL);
   if (lbl != null) {
     label = lbl.getTextData();
   }
 }
 @Override
 public void save(IMemento memento) {
   super.save(memento);
   if (prefId != null) {
     IMemento pref = memento.createChild(PREF_ID);
     pref.putTextData(prefId);
   }
   if (label != null) {
     IMemento lbl = memento.createChild(LABEL);
     lbl.putTextData(label);
   }
 }