@Override
    public void actionPerformed(ActionEvent e) {
        switch (button) {
            case "Single":  contentPanel.addDifficultyPanel(true);
                break;
            case "CO":  contentPanel.addDifficultyPanel(false);
                break;
            case "High":  contentPanel.addHighScorePanel();
                break;
            case "Howto":  contentPanel.addHowToPlayPanel();
                break;
            case "About":  contentPanel.addAboutPanel();
                break;
            case "Sluiten":
                contentPanel.shutDown();
                Database.DatabaseInstance.updateHostNameUserLogout(Database.DatabaseInstance.getUserId());
                break;
        }
    }