clip and overflow:hidden

Clip and overflow:hidden, have a common problem as implemented on
current browsers (haven't tested in Windows, but all common Mac
browsers): they hide content which lies outside the visible area, but
the canvas extends to accommodate the invisible content. This means
that if you're clipping a large content area, say, to create a dhtml
scroller that extends the width of the page, the browser will add a
horizontal scrollbar to bottom of the page for the invisible content,
in effect a scrollbar to nowhere. 

http://phoyt.macbox.com/css_test/clip.html
http://phoyt.macbox.com/css_test/overflow.html

(note, all tested browsers show the effect in the clip example, but
safari treats overflow a bit differently)

I checked the spec and it doesn't seem to say how clipped content
should affect the page canvas, so I can't really claim this is a
browser bug. Maybe future specs could be a bit more clear and state
that hidden content should not affect the page canvas?