public void addListener(FSMouseListener l){
  if (l == null) {
    return;
  }
  if (!_handlers.containsKey(l)) {
    _handlers.put(l,l);
  }
  if (!_enabled && _handlers.size() > 0) {
    _panel.addMouseListener(this);
    _panel.addMouseMotionListener(this);
    _enabled=true;
  }
}

public void addListener ( FSMouseListener l ) { if ( l == null ) { return ; } if ( ! _handlers . containsKey ( l ) ) { _handlers . put ( l , l ) ; } if ( ! _enabled && _handlers . size ( ) > 0 ) { _panel . addMouseListener ( this ) ; _panel . addMouseMotionListener ( this ) ; _enabled = true ; } }
adds a listener to receive callbacks on mouse events .
