Comment 90 for bug 1228250

(In reply to Masayuki Nakano (:masayuki) (Mozilla Japan) from comment #82)
> > That sounds like a minor problem that could be fixed in this bug or a
> > follow-up.
>
> I think that we should decide it in this bug. Smaug, how do you think? I
> believe that if we'd swap deltaX/deltaY for default action, DOM wheel event
> and legacy mouse scroll events should represent it. However, if we do so in
> default settings, there is an issue mentioned in #4 (below).

Doesn't sound like a minor problem.
Since widgets on web pages tend to emulate native scrollable areas, they should get events similar to
native viewport or other scrollable areas.

#4 is tricky, but I think we should favor the more common case, so swap.
How does IE handle this? What does Chrome actually report in delta values?