Disabling thumbnails in Nautilus

[ST]

Hi,

bellow are the steps I undertook to try to disable thumbnails in
Nautilus ( following instruction mentioned here:
https://wiki.gnome.org/dconf/SystemAdministrators ) . It didn't help.
(I'm on Debian Wheezy, which seemingly has no /etc/dconf by default):

-       mkdir -p /etc/dconf/db/local.d/locks

-       nano /etc/dconf/db/local.d/settings
        # /etc/dconf/db/local.d/settings
        # prevent showing thumbnails
        [org.gnome.nautilus.preferences]
        show-image-thumbnails="never"

-       nano /etc/dconf/db/local.d/locks/settings
        # prevent changes to showing thumbnails setting
        org.gnome.nautilus.preferences.show-image-thumbnails

-       mkdir /etc/dconf/profile

-       nano /etc/dconf/profile/local
        system-db:local

-       export DCONF_PROFILE=/etc/dconf/profile

-       dconf update

What's wrong here?

I also tried to disable it using dconf-editor (both as root and as
regular user) and I was not able to change the setting from 'local-only'
to 'never' it looked like it was locked.


I also tried gsettings:

# gsettings get org.gnome.nautilus.preferences show-image-thumbnails
# 'local-only'

# gsettings set org.gnome.nautilus.preferences show-image-thumbnails
"never"

** (process:5834): WARNING **: The connection is closed

** (process:5834): WARNING **: The connection is closed


PS:
I didn't reboot. Do I need to reboot in order for the new settings to
take effect?

I found several dconf files but it doesn't look like they contain any
lock of org.gnome.nautilus.preferences.show-image-thumbnails  and
adding 
[org.gnome.nautilus.preferences]
show-image-thumbnails="never"

to them didn't help either. Here are they:

/var/lib/gdm3/.cache/dconf
/var/lib/gdm3/.cache/dconf/user
/var/lib/gdm3/dconf/db
/var/lib/gdm3/dconf/profile
/var/lib/gdm3/dconf/db/gdm
/var/lib/gdm3/dconf/db/gdm.d
/var/lib/gdm3/dconf/db/gdm.d/00-upstream-settings
/var/lib/gdm3/dconf/db/gdm.d/10-desktop-base-settings
/var/lib/gdm3/dconf/db/gdm.d/90-debian-settings
/var/lib/gdm3/dconf/db/gdm.d/locks
/var/lib/gdm3/dconf/db/gdm.d/locks/00-upstream-settings-locks
/var/lib/gdm3/dconf/profile/gdm

and

/usr/share/gdm/dconf
/usr/share/gdm/dconf-profile
/usr/share/gdm/dconf/00-upstream-settings
/usr/share/gdm/dconf/10-desktop-base-settings
/usr/share/gdm/dconf/locks
/usr/share/gdm/dconf/locks/00-upstream-settings-locks


It looks like dconf update ignores:

/etc/dconf/db/local.d/settings

because if I intentionally  write wrong things there it doesn't
complain.

Any ideas?

Thank you.
ST