function PreviewUpdate() {
  new Ajax.Request(
    location.href,
    {
      method: 'get',
      asynchronous:true,
      parameters:Form.serialize("configure_form")
    }
  );
  PreviewLoading();
  return false;
}

function PreviewLoading() {
  $$('#configure_form select, #configure_form input').each(function(field) {
    field.disable();
  });
  if($('buttons'))        { $('buttons').hide(); }
  if($('spinner'))        { $('spinner').show(); }
}