Also note that only applies if overflow is set to visible. For ie<8, as overflow was explicitly set to auto/scroll it wouldn't apply.
Yes I noticed that and its as though the specs expected the default to be visible but did not take into account what happens when that was changed.
That seems to be why some would say this is not a bug as such but rather just a different interpretation of the specs. However should you add overflow:visible to html and overflow:scroll to body you end up with a page that can't be scrolled in IE6/7 so I don't think IE was listening to the specs at all.:)
I remember old Firefox having a lot of rounding errors that caused content to be clipped and I also remember that overflow itself was badly implemented and had many bugs (content cut off, scrollbars showing when they shouldn't and many other strange bugs).