@Override
  public void readExternal(Element element) throws InvalidDataException {
    ((JDOMExternalizable)transparencyChessboardOptions).readExternal(element);
    String fileNameVisibleAttr = element.getAttributeValue("fileNameVisible");
    fileNameVisible = fileNameVisibleAttr == null || Boolean.parseBoolean(fileNameVisibleAttr);
    String fileSizeVisibleAttr = element.getAttributeValue("fileSizeVisible");
    fileSizeVisible = fileNameVisibleAttr == null || Boolean.parseBoolean(fileSizeVisibleAttr);
  }
@Override
  public void readExternal(Element element)