}
public void addCriterionRequirement(MachineWorkersConfigurationUnit unit,
Button button) {
Bandbox bandbox = (Bandbox) button.getPreviousSibling();
Listitem item = ((Listbox) bandbox.getFirstChild().getFirstChild())
.getSelectedItem();
if (item != null) {
CriterionWithItsType criterionAndType = (CriterionWithItsType) item
.getValue();
bandbox.setValue(criterionAndType.getNameAndType());
if (checkExistingCriterion(unit, criterionAndType.getCriterion())) {
messages.showMessage(Level.ERROR,
_("Criterion previously selected"));