protected override bool IsConnectionPossible(Figure figure)
        {
            if (!figure.Includes (Connection) &&
                figure.CanConnect &&
                Connection.CanConnectStart (figure)) {

                return true;
            }
            return false;
        }
 public override bool CanConnectStart(Figure figure)
 {
     return figure is ClassFigure && !figure.Includes (EndFigure);
 }