Yes, they do ;-) Thanks to the both of you, Alex and Jean Louis !
I have some news about this
Suddenly I couldn't log in anymore as catonano. The login window didn't let the desktopo come up, rather it popped up again and again
I logged in as root and saw some gvfs and gsettings segfaults in the dmesg output.
The only new thing was the XDG_DATA_DIRS setting, so I commented it and than I could log in again as catonano
Of course Emacs icons aren't there anymore, but I can live with that. I didn't use them anyway
While looking for a solution I also found this
$ cat ./.config/user-dirs.dirs # This file is written by xdg-user-dirs-update # If you want to change or add directories, just edit the line you're # interested in. All local changes will be retained on the next run # Format is XDG_xxx_DIR="$HOME/yyy", where yyy is a shell-escaped # homedir-relative path, or XDG_xxx_DIR="/yyy", where /yyy is an # absolute path. No other format is supported. # XDG_DESKTOP_DIR="$HOME/Scrivania" XDG_DOWNLOAD_DIR="$HOME/Scaricati" XDG_TEMPLATES_DIR="$HOME/Modelli" XDG_PUBLICSHARE_DIR="$HOME/Pubblici" XDG_DOCUMENTS_DIR="$HOME/Documenti" XDG_MUSIC_DIR="$HOME/Musica" XDG_PICTURES_DIR="$HOME/Immagini" XDG_VIDEOS_DIR="$HOME/Video"
There's no XDG_DATA_DIRS so you wouldn't immediately think of any conflict
It worked again after commenting that setting nonetheless.