Is there a way to change the system font completely? I mean I want the font from login in screen until every application follow the change.
The font settings are stored in gconf and can be changed easily with
gnome-appearance-properties. They can also be changed using
gconf-editor or the commandline-tool
If you want to change the fonts of the login-screen you have to run these tools as the user gdm like this:
sudo -u gdm dbus-launch gnome-appearance-properties
In some cases this doesn't work and you have to go a more complicated way:
- Log out (so that you are on the login screen)
- figure out what displaynumber the login screen has by pressing Ctrl+Alt+F7(F8,F9). If the login screen is on F7 its number is 0, on F8 it is 1, ..
change to a blank terminal with Ctrl+Alt+F1 and log in with your user. Now run the above command like this (with the correct DISPLAY):
sudo -u gdm DISPLAY=:0 dbus-launch gnome-appearance-properties
now change back to GDM and you should see the appearance properties dialog where you can make any changes you like (background, too).
Maybe you need to go to System-->Preferences-->Appearance-->Fonts and change it from there.