Home directories
----------------

I'd say that under a user's home dir, all program stuff should be under
one of those dirs, and nowhere else.

config and state may be a bit fuzzy, because in a way some state
may be config, but modified in a different way, and that could get us
into persistence.

.config ($XDG_CONFIG_HOME)
~~~~~~~

For stuff that the user specified explicitely (I'd make the disctinction
of things the user may edit with a text editor).

.state ($XDG_DATA_HOME ??)
~~~~~~

For stuff like history, be it command or urls etc. logs, window position.
But you may consider some of those as a different kind of config
like ui config, also .state could be all session related stuff.

freenode.net #hurd-2006-08.log
03:17 < antrik> braindmg: IMHO, in an ideal world *all* config should be
                managed via sessions; and all session data should be manually
                editable...
03:17 < KiBi> Using XML? ;-)
03:17 < braindmg> antrik: well for me it's a bit different to lose my muttrc
                  than my last visited webpages for example
03:18 < braindmg> I'd like also to store .config on a scm and probably not
                  .state
03:18 < braindmg> it gets fuzzied when used on different boxes
03:18 < braindmg> I may backup it per host though maybe
03:18 < KiBi> Agreed on .config in SCM.
03:18 < braindmg> or on a per-host repo
03:18 < braindmg> but you can easily share .config
03:19 < antrik> KiBi: well, possibly. users should be able to view structured
                data in various ways -- either as XML, or sexps or whatever,
                or as directory trees. the internal representation doesn't
                really matter that much
03:19 < braindmg> that's one of my most annoying concerns right now with my
                  home under svn

.cache ($XDG_CACHE_HOME)
~~~~~~

For stuff that can be removed because it can be regenerated or
reretrieved. Thinks like thumbnails, ccache data.

.temp ($TMP, $TEMP, etc)
~~~~~

For stuff that is temporary, used during the program execution and can be
removed once the program is not running anymore.