code: public void setShowSubtext(final boolean showSubtext) {
          if (showSubtext)
              attrMixin.setAttribute(SHOW_SUBTEXT, Boolean.toString(true));
          else
              attrMixin.removeAttribute(SHOW_SUBTEXT);
      }
docs: When set to <code>true</code>, display sub-text associated with a
  selected option in the button.<br>
  <br>
  Defaults to <code>false</code>.
  
  @param showSubtext