use diff tool before actually make changes

Hi,
I have an idea from Gentoo's etc-update. Instead of gst saving changes
directly to file, it creates a new config file and uses a diff tool
such as meld to show differences between the old one and the new
one. Then users can accept changes or modify themselves. It is ok?

BTW, i would like to contribute gentoo support for
services-admin. Has services-admin supported gentoo already?

I'm considering gentoo support for network-admin too, but it's a bit
hard because gentoo holds net info in a bash script with lots of
comments for manually editting. Is there any bash parser yet?
Regards,
-- 
Bi Cờ Lao