public void addItemBoundsListener(ItemBoundsListener ibl){
  if (m_bounders == null)   m_bounders=new CopyOnWriteArrayList();
  m_bounders.add(ibl);
}

public void addItemBoundsListener ( ItemBoundsListener ibl ) { if ( m_bounders == null ) m_bounders = new CopyOnWriteArrayList ( ) ; m_bounders . add ( ibl ) ; }
add an itemboundslistener to receive notifications when the bounds occupied by the visualitems in this display change .
