public void writeHistory(DataOutput output) {
        try {
            output.writeInt(VERSION);
            sourcePanel.writeHistory(output);
            destinationPanel.writeHistory(output);
            int comboCount = commandCombo.getItemCount();
            Vector commands = new Vector();
            for (int i = 0; i < comboCount; ++i) {
                String nextCommand = (String) commandCombo.getItemAt(i);
                if (!nextCommand.trim().equals("")) {
                    commands.add(nextCommand);
                }
            }
            output.writeInt(commands.size());
            Iterator iter = commands.iterator();
            while (iter.hasNext()) {
                output.writeUTF((String) iter.next());
            }
        } catch (IOException e) {
            // NYI
        }
    }