private void writeObject(ObjectOutputStream stream) throws IOException {
        stream.defaultWriteObject();
        SerialUtilities.writeStroke(this.angleGridlineStroke, stream);
        SerialUtilities.writePaint(this.angleGridlinePaint, stream);
        SerialUtilities.writeStroke(this.radiusGridlineStroke, stream);
        SerialUtilities.writePaint(this.radiusGridlinePaint, stream);
        SerialUtilities.writePaint(this.angleLabelPaint, stream);