Comment 6 for bug 486284

> Are there any official specifications on how this should actually
> work - rather than saying "other browsers do it like that"?

Not yet. HTML5 is specifying this behavior (and Firefox 3 is following the draft HTML5 spec).

> then we'd have to duplicate all IE quirks

We basically do duplicate all the IE quirks that don't violate existing specifications and are needed to make significant numbers of existing web sites work... So do all the other browsers.