function _onClickPlusLabel() {
            var sCategory, welCategory, nLabel;

            for (sCategory in htElement.htCategory) {
                if ($(this).data('category') == sCategory) {
                    continue;
                }

                welCategory = htElement.htCategory[sCategory];

                nLabel = welCategory.children('.label-list').children().length;

                if (nLabel == 0 && isRequired(sCategory)) {
                    delete htElement.htCategory[sCategory];
                    welCategory.remove();
                }
            }

            htElement.welInputLabel.data('category', $(this).data('category'));

            new yobi.ui.Typeahead(htElement.welInputLabel, {
                "sActionURL": htVar.sURLLabels,
                "htData": {
                    "category":  $(this).data('category'),
                    "project_id": htVar.nProjectId,
                    "limit": 8
                }
            });

            htElement.welInputCategoryBox.hide();
            htElement.welInputLabelBox.show();
            $(this).after(htElement.welInputLabelBox);
            jQuery.map(htElement.aBtnPlusLabel, function(btn) { btn.show(); });
            $(this).hide();

            if (!htElement.welInputLabel.is(":focus")) {
                htElement.welInputLabel.trigger('focus');
            }
        }
When a plus button in each category is clicked..