searchForm = new SearchForm(supplyItemDS);
//when showing options in the combo-box, only show the options from the selected category if appropriate
final ComboBoxItem itemNameCB = searchForm.getItemNameField();
itemNameCB.setPickListFilterCriteriaFunction(new FilterCriteriaFunction() {
public Criteria getCriteria() {
ListGridRecord record = categoryTree.getSelectedRecord();
if ((itemNameCB.getValue() != null) && record != null) {
Criteria criteria = new Criteria();
criteria.addCriteria("category", record.getAttribute("categoryName"));