Why are there 3 roundcube directorys and which is the relevant one?

[femco]

Hi, iam new to roundcube and a linux beginner. I just installed roundcube on my ubuntu 12.04 server via apt-get (apt-get install roundcube roundcube-mysql roundcube-plugins roundcube-plugins-extra).
I noticed that there are 3 roundcube directorys:
- /etc/roundcube
- /var/lib/roundcube
- /usr/share/roundcube

each contains a plugins directory and a main.inc.php,
i realised this as i tried to edit the plugins configuration inside the /etc/roundcube/plugins directorys, each plugin directory contains only an empty config.inc.php file with a reference to the /usr/share/roundcube/plugins/plugindir version.

I think i need some help here.
What is the purpose of these directorys? What is the reason that there are 3 of them?
And which one is the one i have to add new plugins or edit the main.inc.php?

[ABerglund]

That is something that the Ubuntu packagers have done. If you install from source (unpack the tarball, that's about it), it is totally self-contained in one directory. I'd also guess that the version supplied via apt-get is not fully current.

[femco]

Ok thanks, it seems that there is not realy so much redundancy i thought it were, because everything important in /usr/share/roundcube is symlinked to /etc/roundcoube even the plugin config.inc.php files.
And most of the stuff in /var/lib is symlinked to /usr/share