See news://news.mozilla.org/379D051A.233401B0%40meer.net for context on why it's needed.
This is in the core DOM, maybe it's easy to wire up to XUL? Hmm, why isn't it just there? /be
Because XUL has its own implementation of all the DOM APIs.
Give this a whirl in M10.
Moving out non-critical tasks.
spam: changing qa contact from ckritzer -> paulmac for xul bugs
BULK MOVE: Changing component from XUL to XP Toolkit/Widgets: XUL. XUL component will be deleted.
spam, open xptoolkit qa contact moving over to jrgm
Ancient bug, may have been fixed by bug 124412?
This was fixed by bug 124412