code: public void setShowIcon(final boolean showIcon) {
          if (!showIcon)
              attrMixin.setAttribute(SHOW_ICON, Boolean.toString(false));
          else
              attrMixin.removeAttribute(SHOW_ICON);
      }
docs: When set to <code>true</code>, display icon(s) associated with
  selected option(s) in the button.<br>
  <br>
  Defaults to <code>true</code>.
  
  @param showIcon