public function getDifference()
{
if ($this->_new === null) {
return $this->_null;
} else {
$css = $this->getCssClassDiff();
$style = $this->getStyleDiff();
if ($css !== null || $style !== null) {
return array('CssClass' => $css, 'Style' => $style);
} else {
$this->_null;
}
}
}