code: public void setStyle(final String styleName) {
          if (styleName != null)
              attrMixin.setAttribute(STYLE, styleName);
          else
              attrMixin.removeAttribute(STYLE);
      }
docs: Set the customized style name to the select.<br>
  <br>
  Defaults to <code>null</code>.<br>
  <br>
  <b>IMPORTANT</b>: This method will override the style set by
  {@link #setType(ButtonType)} and/or {@link #setSize(ButtonSize)}.
  
  @param styleName