code: public void disable(String disabledReason) {
  
          if (m_isEnabled
              || (CmsStringUtil.isNotEmptyOrWhitespaceOnly(disabledReason) && !disabledReason.equals(m_disabledReason))) {
              m_isEnabled = false;
              m_disabledReason = disabledReason;
              m_scrollList.addStyleName(I_CmsInputLayoutBundle.INSTANCE.inputCss().disabled());
              setListEnabled(m_scrollList, false, disabledReason);
          }
      }
docs: Disabled the category selection.<p>
  
  @param disabledReason the disable reason, will be displayed as check box title