Pages that have multi-line suggestions (like <https://launchpad.net/distros/ubuntu/dapper/+source/gnome-screensaver/+pots/gnome-screensaver/it/+translate?offset=10>) are often very wide. This is because the pages contain <pre> with long lines.
Originally this was happening just with Konqueror and Safari, because Gecko noticed the {overflow: auto;} applied to the <pre>, and shortened the element with scrollbars to keep the page a sensible width. KHTML also supports {overflow: auto;}, but prefers to widen the page so that it doesn't have to add scrollbars.
Mauricio, please give the URL of a page where this happens. Thanks.