public void addWizardObserver(WizardObserver observer){
  listeners.add(observer);
  if (!listeningToImpl) {
    l=new ImplL();
    impl.addWizardObserver(l);
    listeningToImpl=true;
  }
}

public void addWizardObserver ( WizardObserver observer ) { listeners . add ( observer ) ; if ( ! listeningToImpl ) { l = new ImplL ( ) ; impl . addWizardObserver ( l ) ; listeningToImpl = true ; } }
add a wizardobserver that will be notified of navigability and step changes .
