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

            if (!htElement.welInputCategory.is(":focus")) {
                htElement.welInputCategory.trigger('focus');
            }
        }
When a plus button in the end of the Label Board is clicked..