How to enable new lock screen on gnome 3.6?

Solution 1:

( please only try the following steps if you know how to use the terminal! )

First I would have to know if even your login-screen is old as well?

If so, maybe this will help you.

you still see the old lock/login-screen because you are still using the Ubuntu default display manager lightdm, I guess..

To get the new L&F you have to set gdm as default-manager. ( be sure that gdm 3.6 is installed on your machine! )

sudo dpkg-reconfigure gdm

Now, you have to stop lightdm but this will shut down your display-manager and you will only see a terminal but that's fine.

sudo service lightdm stop

Right after lightdm has stopped, login in the prompting shell and execute following

sudo service gdm start

That's it!