protected synchronized void addEnterListener(Hashtable<TxState,Set<EventListener>> listeners,EventListener lstnr,TxState state){
  Set<EventListener> lstnrs=listeners.get(state);
  if (lstnrs == null)   lstnrs=new HashSet<EventListener>();
  if (!lstnrs.contains(lstnr))   lstnrs.add(lstnr);
  listeners.put(state,lstnrs);
}

protected synchronized void addEnterListener ( Hashtable < TxState , Set < EventListener > > listeners , EventListener lstnr , TxState state ) { Set < EventListener > lstnrs = listeners . get ( state ) ; if ( lstnrs == null ) lstnrs = new HashSet < EventListener > ( ) ; if ( ! lstnrs . contains ( lstnr ) ) lstnrs . add ( lstnr ) ; listeners . put ( state , lstnrs ) ; }
help function for adding enter listeners .
