private void readObject(ObjectInputStream stream)
        throws IOException, ClassNotFoundException {
        stream.defaultReadObject();
        this.firstBarPaint = SerialUtilities.readPaint(stream);
        this.lastBarPaint = SerialUtilities.readPaint(stream);
        this.positiveBarPaint = SerialUtilities.readPaint(stream);
        this.negativeBarPaint = SerialUtilities.readPaint(stream);