private void handleTime(int year, int month) {
        int newMonth = month;
        int newYear = year;
        if (newMonth == 0) {
            newMonth = 12;
            newYear -= 1;
        } else if (newMonth == 13) {
            newMonth = 1;
            newYear += 1;
        }
        RoosterProgramma.getInstance().showPanel(new EmployeeTimeSheet(employee, newYear, newMonth));
    }