protected Widget attachEdgeWidget(String edge) {
ConnectionWidget connection = new ConnectionWidget(this);
connection.setRouter(router);
// �����ɾ�� connection.setToolTipText("������Ƶ㣺���˫��");
connection.setTargetAnchorShape(new TriangleAnchorShape(6, true, false,
false, 6.0));
connection.setControlPointShape(PointShape.SQUARE_FILLED_BIG);
connection.setEndPointShape(PointShape.SQUARE_FILLED_BIG);
connection.setLineColor(backgroundColor); // ������ɫ
/*