I found a pretty funny bug in FireFox (v1.0).
When you go into any Livejournal posts and are also viewing the comments with the related blog entry, try to scroll down with your mouse-wheel or the mouse middle button + move mouse up/down.

Everytime I did this, the “frame” of the browser window scrolled up, so the lower arrow on the vertical scroll bar ended somewhere around the center-left of the screen (opposed to bottom-left).

You can view the recorded screenshot video AVI file here

Yay! My first Bugzilla submission (ID#275843)