Yesterday Apple released Mac OS 10.8.4 including Safari 6.0.5 “which improves stability for some websites with chat features and games”. The funny part: it actually worsens stability “for some websites with chat features and games” (Facebook).
Try chatting to someone in your Facebook newsfeed. While typing and more specifically while making a break (shift+enter), the whole page scrolls down. It might be possible that this only occurs in the new Facebook Newsfeed which I am using. I already filed a bug through Apples incredible modern Bug Reporter. We’ll see if it will get any attention.