On Sun, 27 Nov 2011 23:03:13 +0000
Tiago Marques <tiagomnm@...> wrote:

> Once upon a time, Gentoo users could have multiple versions of KDE
> installed without any compatibility problems by using the following prefix
> system:
> 
> - */usr/kde* as the main dir
> - /usr/kde/3.5 as the dir for the 3.5 install
> - /usr/kde/3.4 as the dir for the 3.4 install
> 
> Now, I don't know how it handled the paths in the environment but
> everything was transparent and worked great. One would just select which
> version to boot on KDM and everything would work fine. I think the session
> script was used to set up the proper paths but I'm not sure.

Some path setting occurs in startkde under Gentoo:

# Gentoo: setup environment, filter other slotted KDE installs from PATH
_KDEDIR=/usr/kde/3.5
export PATH=${_KDEDIR}/bin:$(echo ${PATH} | sed 's/$/:/g;s#/usr/kde/[^/]*/s\?bin/\?:##g;s/:$//g')
export ROOTPATH=${_KDEDIR}/sbin:${_KDEDIR}/bin:$(echo ${PATH} | sed 's/$/:/g;s#/usr/kde/[^/]*/s\?bin/\?:##g;s/:$//g')
export LDPATH=/usr/kde/3.5/lib:/usr/kde/3.5/lib64:/usr/kde/3.5/lib32:${LDPATH}
export XDG_DATA_DIRS=${_KDEDIR}/share:$(echo ${XDG_DATA_DIRS} | sed 's/$/:/g;s#/usr/kde/[^/]*/share/\?:##g;s/:$//g')

Presumably, the seds are the filter that handle other versions of KDE.