Guide: Turn Trisquel 4.5 and 5.0 into Trisquel 4.0

I thought some people might be interested in this.

Desktop background
Just right click on the mouse on the desktop, select "Change Desktop Background" and choose the Taranis background (alternatively, the Background menu can be reached via System->Preferences->Appearance).

Login screen
Type this in the terminal:
$sudo cp /usr/share/applications/gnome-appearance-properties.desktop /usr/share/gdm/autostart/LoginWindow
Logout and login.
Select the Trisquel Taranis background.
Open the terminal and type this:
$sudo unlink /usr/share/gdm/autostart/LoginWindow/gnome-appearance-properties.desktop

GRUB menu
Download trisquel-grub.png from this message and save to Desktop (or copy from /usr/share/backgrounds of Trisquel 4.0).
Backup new trisquel-grub.png image. Open the terminal and type:
$sudo mv /usr/share/backgrounds/trisquel-grub.png /usr/share/backgrounds/trisquel-grub-backup.png
Transfer the downloaded image to the right location.
Open the terminal and type:
$cd Desktop
$sudo cp trisquel-grub.png /usr/share/backgrounds/
Now update grub by typing in the terminal
$sudo update-grub

Splash screen
Remove the new splashscreen. Open a terminal and type:
sudo aptitude remove plymouth-theme-trisquel-logo
Now download and install the Taranis package from here (open Abrowser, click on the .deb file for your architecture (32 or 64 bit) and select open with GDebi to install it):
http://packages.trisquel.info/taranis-updates/plymouth-theme-trisquel-logo
Since you downgraded a package you will probably not want to see upgrade prompts. Just open a terminal and type:
$sudo -s
Now enter your password and type
#echo plymouth-theme-trisquel-logo hold | dpkg --set-selections

Trisquel theme
Remove the old Trisquel theme. Open a terminal and type:
$sudo aptitude remove elementary-icon-theme trisquel-icon-theme trisquel trisquel-desktop-common
(Don't worry this doesn't remove Trisquel :) )
Now download and install the Trisquel Taranis versions of elementary-icon-theme and trisquel-icon-theme (open Abrowser, click on the .deb files for your architecture (32 or 64 bit) and select open with GDebi to install them):
http://packages.trisquel.info/taranis-updates/trisquel-icon-theme
http://packages.trisquel.info/taranis/elementary-icon-theme
In order not to be reminded to upgrade these versions open a root terminal and type:
#echo trisquel-icon-theme hold | dpkg --set-selections
#echo elementary-icon-theme hold | dpkg --set-selections