From GTK+-1.2 to GTK+-2.2 questions

[Mirko <mikkx tiscali it>]

I was updating my old GTK version, 1.2, to the newest one 2.2, but the 
dubts rises after I 've installed all dependencies and GTK itself. The 
old one version was installed in /usr, the 2.2 version in /usr/local. It 
's ok or I must change installation path? The old version must be 
deleted? What about programs like Mozilla who requires some libraries 
from old version 1.2? In the home-page of GTK it says that  GTK+-1.2  
and  2.2  can be keep both installed on the system, how? Thanks.