I've just installed Ubuntu GNOME 15.04, a bunch of programs and drivers but I want to install the flat studio shell theme that logan uses. I've enabled User themes, put it in .themes and it still doesn't appear in the theme selection.
Just followed this, the tar is extracted in .themes, however I still only have the Default option for shell theme in tweak tool. I've killed the tool and restarted it to no avail.
I found the problem. I am running GNOME 3.14.4 when the theme doesn't support that. By using this download I was able to make the theme work however:
EDIT: If anyone else wants to do this, I'd like to point out in Tweak Tool you also need to change the Window to Numix and GTK+ to Numix-FlatStudio-something as well as changing the Shell theme.