This is appearing in Safari 3.0.4 for Windows (523.12.9)
In Gmail, a little floating box appears in the lower right hand part of the content area to show that other people have replied to a conversation. In Safari, this floating box actually overlaps a horizontal scroll bar, if such a bar is present. I will attach a screenshot that shows this behavior.
Steps to reproduce:
1. Log into gmail
2. Open a conversation
3. Expand a number of the messages such that the box which indicates the existence of more responses than shown on screen appears. Observe that this indicator overlaps part of the browser chrome (the vertical scroll bar). You may need to resize your browser to get a vertical scroll bar to appear.
Created attachment 17732 [details]
Screenshot showing content overlapping horiz. scroll bar
FWIW, I ran into Bug 16328 while trying to reproduce this on Mac OS X 10.4.11.
I think this behaves as expected - the scrollbar belongs to a frame, not to the page. The box is absolutely positioned on the page such that it overlaps the bottom of the frame, which happens to be displaying the scroll bar.
Although this is very strange behavior, it does seem to be in line with what other browsers are doing. I just tried it in IE and FF and got the same result. (It surprises me that this is possible, but that's a different story.) Probably safe to close this out given that.
Closing as INVALID per comment #4.