private void readObject(ObjectInputStream stream) 
            throws IOException, ClassNotFoundException {
        stream.defaultReadObject();
        this.store = new TreeMap();
        int keyCount = stream.readInt();
        for (int i = 0; i < keyCount; i++) {
            Comparable key = (Comparable) stream.readObject();
            Stroke stroke = SerialUtilities.readStroke(stream);
            this.store.put(key, stroke);