public void editStartURL() {
        JFileChooser fc = new JFileChooser();
        fc.setMultiSelectionEnabled(false);

        int result = fc.showOpenDialog(null);
        if (result != JFileChooser.APPROVE_OPTION) return;

        URL url = null;
        try {
            url = fc.getSelectedFile().toURI().toURL();
        } catch (MalformedURLException e) {
            JOptionPane.showMessageDialog(null, e.getMessage());
            return;
        }

        rootPage.setURL(url);
        rootPage.setContainsNames(true);
        rootPage.setContainsPages(false);
    }