public void addVetoableChangeListener(VetoableChangeListener listener){
  if (m_changeSupport == null)   m_changeSupport=new VetoableChangeSupport(this);
  if (listener != null)   m_changeSupport.addVetoableChangeListener(listener);
}

public void addVetoableChangeListener ( VetoableChangeListener listener ) { if ( m_changeSupport == null ) m_changeSupport = new VetoableChangeSupport ( this ) ; if ( listener != null ) m_changeSupport . addVetoableChangeListener ( listener ) ; }
add vetoable change listener
