/**
  * @param graphSelectionEvent GraphSelectionEvent
  * @param cell Object
  */
 private void handleSelection(GraphSelectionEvent graphSelectionEvent, Object cell) {
   if (selected(graphSelectionEvent.getCells(), cell)) {
     if (graphSelectionEvent.isAddedCell(cell)) {
       addAll(cell);
     } else {
       removeAll(cell);
     }
   }
 }
 /**
  * Invoked whenever the selection of the graph changes.
  *
  * @param graphSelectionEvent GraphSelectionEvent
  * @todo Implement this org.jgraph.event.GraphSelectionListener method
  */
 public void valueChanged(GraphSelectionEvent graphSelectionEvent) {
   Object[] cells = graphSelectionEvent.getCells();
   for (int i = 0; i < cells.length; i++) {
     handleSelection(graphSelectionEvent, cells[i]);
   }
 }