Running kde2 and kde3 apps in /usr?

[Kurt Granroth]

There are any number of ways to be able to run kde2 and kde3 apps on the 
same system.. but afaik, they all involve putting the two systems in 
different root directories.  This doesn't work on, say, Debian systems, 
though since all of kde needs to be in /usr.

Now it is possible with the some tweaking of version numbers to get all of 
the kde libraries from kde2 and kde3 to install in /usr/lib.  This isn't 
very hard since most of the "could-be-problematic" ones go into the 
/usr/lib/kde2 or /usr/lib/kde3 subdirs.  So far, so good.

The question at hand, though, is just how much do kde apps need the "helper" 
apps (like dcopserver) from their own version?  Can a kde2 app use the kde3 
dcopserver, for instance?  And beyond that, is there anything I'm missing 
that would absolutely prevent kde2 apps from running on a kde3 system (with 
kde2 libs)?

FWIW, I tried to very very quick tests with kdcop and kmail.. the former 
worked just fine, the latter crashed.  I thought I'd ask here before going 
into too much investigation on the why's.

Anybody *know* the answer?
-- 
Kurt Granroth - "KDE -- Conquer Your Desktop"
KDE Developer/Evangelist | granroth at kde.org
http://www.granroth.org  | kurt at granroth.org