Here's a more detailed fix:
deleting ~/.config was not a very appealing fix for me since I don't
want to lost everything :-)
When double clicking a file in nautilus, it ends up calling "gio open".
stracing gio:
$ strace -f gio open <some file> 2>&1 | grep '\.config'
it shows that at some point an xfce4 helper file is read (I do have xfce
installed as well on my laptop):
stat("/home/<username>/.config/xfce4/helpers.rc", {st_mode=S_IFREG|0644,
st_size=41, ...}) = 0
this file contained the following lines:
FileManager=nautilus
MailReader=icedove
I moved away this file and it fixes the issue.
Anyway I don't know why, at some point, gio reads this xfce file, it
seems a bit strange.
For information here is the full ouput of
$ strace -f gio open <some file> 2>&1 | grep '\.config'
[pid 16711] access("/home/<username>/.config", R_OK|X_OK) = 0
[pid 16711] inotify_add_watch(7, "/home/<username>/.config",
IN_MODIFY|IN_ATTRIB|IN_CLOSE_WRITE|IN_MOVED_FROM|IN_MOVED_TO|IN_CREATE|IN_DELETE|IN_DELETE_SELF|IN_MOVE_SELF|IN_UNMOUNT|IN_ONLYDIR
<unfinished ...>
[pid 16711] openat(AT_FDCWD,
"/home/<username>/.config/gnome-mimeapps.list", O_RDONLY) = -1 ENOENT
(No such file or directory)
[pid 16711] openat(AT_FDCWD, "/home/<username>/.config/mimeapps.list",
O_RDONLY) = 8
mkdir("/home/<username>/.config", 0700) = -1 EEXIST (File exists)
stat("/home/<username>/.config", {st_mode=S_IFDIR|0755, st_size=4096,
...}) = 0
stat("/home/<username>/.config/xfce4/helpers.rc", {st_mode=S_IFREG|0644,
st_size=41, ...}) = 0
openat(AT_FDCWD, "/home/<username>/.config/xfce4/helpers.rc", O_RDONLY) = 7
--
Matthieu
