With previous versions of Ubuntu, to install a new theme it would suffice to copy it to the
~/.themes folder. If I do the same on Ubuntu 15.04 the theme never shows up the Unity Tweak Tool or the Appearance tab of the Settings tool.
What is the correct procedure on Ubuntu 15.04?
Update: I have tried various things following the suggestions from Sadi below. I am able to install themes with these two procedures:
Directly from a PPA (e.g.
Compiling from source and then issuing something like
sudo make install.
So far no theme copied directly into
/usr/share/theme ever appears in the tweak tools; irrespective of folder permissions.