For a reason that I cannot find, the page quoted originally sizes itself too wide for the viewport. Resizing the viewport and thus forcing a reflow solves the problem; the content no longer exceeds the viewport width and the scroll bars dissapear. This problem is not related to the CSS on the page. The problem still occurs when I take the styles out. However, taking even a small part of the HTML out (any small part) causes the problem to dissapear.

I was seeing the problem more with http://www.bath.ac.uk/%7Epy8ieh/internet/eviltests/htmlbodyrendering1.html than with the above URL Now it's okay with both. The problem was in the new scrollbar code where we're smarter about only showing/leaving-room-for the vertical scrollbar if needed

Regression. :-( The error has come back, although in slightly less drastic form. Now you have three or so pixels of horizontal scrolling. Reflowing the page does not fix the problem anymore. You are also missing the last twelve or so pixels (the extra scroll bar's height in fact) at the bottom of the canvas, which the vertical scroll bar won't let you see. I am sure this is because the horizontal scroll bar is not supposed to appear, and so its height is not being considered. This bug is visible on *every* page, except those that explicitly size the BODY element (rare). The following pages demonstrate the vertical problem well since they have borders/padding/margins on BODY that should be the same size all the way around. http://www.bath.ac.uk/%7Epy8ieh/internet/eviltests/htmlbodyrendering1.html http://www.bath.ac.uk/%7Epy8ieh/internet/eviltests/htmlbodyrendering4.html

*** Bug 3113 has been marked as a duplicate of this bug. ***

per leger, assigning QA contacts to all open bugs without QA contacts according to list at http://bugzilla.mozilla.org/describecomponents.cgi?product=Browser

Marking this FIXED, because it seems to work okay now. It was a real problem, which is why I'm not marking it WORKSFORME I believe this was fixed by Kipp when he fixed bug # 2525