theme engine install dir question

[Seth Nickell <snickell stanford edu>]

So I'm current installing Crux to $(libdir)/gtk-2.0/engines. It seems to
work fine here, but I notice that gtk-engines installs into
$(libdir)/gtk-2.0/$(GTK_VERSION)/engines.

Ordinarily I would just follow gtk-engine's footsteps, but I have some
questions. If I understand things correctly there's a cost to this.
Namely, since Crux is (at least for now) probably going to be
distributed independently on themes.org its really important to be able
provide tarballs/binary packages that users can just download and
install. 

Am I correct in supposing that if I build binary packages that install
into lib/gtk-2.0/2.0.0/Crux but the user has GTK 2.0.3 they wouldn't be
able to use the theme? Worse, won't the theme show up in the list but
the engine library won't be available causing a broken theme to show up?

If the last question is true, it seems like installing into versioned
dirs for theme engines is always a loss. Because the theme will show up
and be broken no matter what, and at least in the unversioned case you 
stand a (high, right?) chance of GTK being compatible theme engine wise
between versions.

Thanks!

-Seth