I was playing around with some settings, and now I need to reset GNOME to it's defaults – how do I do that?
Ubuntu 15.10 and before
To reset the customization of gnome fonts done using System ⇒ Preferences ⇒ Appearance ⇒ Fonts use the following commands.
Basically these commands remove the customization by deleting the user instance of the gconf keys in which case the environment falls back to system defaults.
gconftool-2 --unset /desktop/gnome/interface/font_name gconftool-2 --unset /desktop/gnome/interface/document_font_name gconftool-2 --unset /desktop/gnome/interface/monospace_font_name gconftool-2 --unset /apps/metacity/general/titlebar_font gconftool-2 --unset /apps/nautilus/preferences/desktop_font
Though the key identifiers end with
name (at least in the first three instances) what is stored against them is the complete font spec (like family/font name, size, style etc).
Since these keys are stored inside your home directory they take effect in all ubuntu installations that share the home partition. The .gconf directory inside your home directory is where all this info is stored.
- ~/.gconf/desktop/gnome/interface/%gconf.xml stores the info for
- ~/.gconf/apps/metacity/general/%gconf.xml stores /apps/metacity/general/titlebar_font
- ~/.gconf/apps/nautilus/preferences/%gconf.xml stores /apps/nautilus/preferences/desktop_font
So a crude way to reset the font info could be to temporarily rename/move these files. However this should be done when the user's gnome session is not active (thus from a tty session a la Ctrl+Alt+F1).
Of course these files have other keys in the same category that have nothing to do with font properties so moving the entire file would mean that the customizations for those are also lost. The way to deal key-wise is using gconftool-2 as mentioned above.
I've definitely ran into these issues when testing with different desktop environments and I can understand your concern. One thing to keep in mind is that KDE likes to mind its own business so when you install KDE without recommends or suggests turned on your KDE environment is entirely on its own.
You also have to be careful for display managers. Unity, LXDE and XFCE use LDM. KDE uses KDM, and Gnome uses GDM. Usually if you keep suggests and recommends turned off you will be fine. Another good way to look at dependencies
apt-cache depends [package-name]
If you want to just look at core dependencies
apt-cache depends [package name] | grep Depends
To get to your question, configuration files are tricky. Unity has been trying to get off of Gnome dependencies for a while and for the most part it has. Unity and Gnome both depend on similar libraries like: Cairo, ATK, GTK, Glib, Compiz and probably others that I couldn't find.
Your best bet is to experiment in a safer environment. You can download an Ubuntu ISO and do some testing in VirtualBox. Or you can backup everything onto an external hard drive and test directly on your machine, and if something bad happens then you have a backup.
I'm sorry I couldn't give you a more direct answer, but I'm sure a more direct answer would be helpful to many people who also want to try out and experiment with different desktops environments.