are tweaks additive?

[Kieren Richard MacMillan]

[ Mac OS X 10.3.3, via Fink;  Lilypond 2.1.35-1 ]

Hey, y'all --

Once again, I can't keep up with HW, J, and M (the Finkster): the 
versions are coming too fast and furious!  ;-)

From the Release Notes, I noticed that somewhere along the way,
> Tweaks made with \override and \revert no longer hide tweaks at higher 
> context levels.

Does this mean that tweaks are now additive, in the sense that (e.g.) 
if I have set Staff.extra-offset to 3 and then set Voice.extra-offset 
to 2, that the total extra-offset for items in that Voice context is 5?
Is this different from how it happened in the past (i.e., would the 
total V.e-o be 2 in my example)?

Thanks!
Kieren.