Obsolete classes

[Patrick Julien]

> > Do we really need paint-offset? It does not make sense to me, because you
> > can always move the layers.
>
> In October, Patrick made a case for this -- don't know exactly what it was,
> and it isn't a concept that I can wrap my mind around, but try if you can
> find it, and see what you think. _I_'m not attached to it.

Not really a case, you asked me what they we're used for.