Q:

How to install theme without using user-theme extension?

I'm using Ubuntu 12.04 with Gnome Shell 3.4. Since day one I had some random crashes mainly after reloading or during search. After a lot of research I concluded that user-theme extension is to blame. Only when disabled Gnome Shell runs 100% smoothly. So my question is: Is there a way to install a theme without using user-theme extension?
edit: Trying to install it via Gnome Tweak Tool without user-theme extension won't work because of [this][1].

A:

Yes you can.
Extract your theme to ~/themes or /usr/share/themes
I use this command for manually change theme and icon on ubuntu.
Open terminal Ctrl+Alt+T and run following command:
Icon Pack
gsettings set org.gnome.desktop.interface icon-theme 'theme'

Theme
gsettings set org.gnome.desktop.interface gtk-theme 'theme'

gsettings set org.gnome.desktop.wm.preferences 'theme'

gconftool-2 --set --type string /apps/metacity/general/theme 'theme'

Change 'theme' with your theme name

