public void actionPerformed(ActionEvent arg0) {
JComboBox combo = (JComboBox) arg0.getSource();
ComboOption option = (ComboOption) combo.getSelectedItem();
if (MessageBox.showConfirmYesNo(MessageBox.C_CHANGE_DAY_MODE) != MessageBox.ANSWER_YES) {
//rollback
combo.removeActionListener(this);
combo.setSelectedItem(dayUI[dayOfWeek.getEuropean()].currentSelection);
combo.addActionListener(this);
return;
}