code: public void setShowContent(final boolean showContent) {
          if (!showContent)
              attrMixin.setAttribute(SHOW_CONTENT, Boolean.toString(false));
          else
              attrMixin.removeAttribute(SHOW_CONTENT);
      }
docs: When set to <code>true</code>, display custom HTML associated with
  selected option(s) in the button. When set to <code>false</code>,
  the option value will be displayed instead.<br>
  <br>
  Defaults to <code>true</code>.
  
  @param showContent