instead of:
`public void registerCssFile(string $url, string $media='')`
I'd request a third parameter:
`public void registerCssFile(string $url, string $media='', string $condition='')`
so this:
Yii::app()->clientScript->registerCssFile('/css/ie.css', 'screen, projection', 'lt IE 8');
would produce this:
<!--[if lt IE 8]> <link rel="stylesheet" type="text/css" href="/css/ie.css" media="screen, projection" /> <![endif]-->