Comment 3 for bug 1057000

As a temporary fix, here's how I downgraded my Nvidia drivers and regained the default behavior of Unity 5.16:

First, disable the Ubuntu-X team PPA if it is enabled:

 - Hit ALT + F2 and run software-properties-gtk
 - Click on the Other Software tab
 - Find the following entries and uncheck them:
   * http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu precise main
   * http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu precise main (Source Code)

Next, log out and on the login screen, hit ALT + F1 to continue.

Back up the current xorg.conf file:

 - sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.NVIDIA

Now, remove the existing Nvidia drivers:

 - sudo apt-get --purge remove nvidia-common nvidia-current nvidia-settings

Next, reboot:

 - sudo reboot

After restart, hit ALT + F1 and download the previous NVidia drivers:

 - Ubuntu 32-bit:
   * cd $HOME/Downloads && wget http://us.download.nvidia.com/XFree86/Linux-x86/304.43/NVIDIA-Linux-x86-304.43.run

 - Ubuntu 64-bit:
   * cd $HOME/Downloads && wget http://us.download.nvidia.com/XFree86/Linux-x86_64/304.43/NVIDIA-Linux-x86_64-304.43.run

Once downloaded, time to install the previous driver release, but first, we need to kill the current X Server/LightDM instance:

 - sudo service lightdm stop

To install for 32-bit Ubuntu:
 - sudo chmod +x NVIDIA-Linux-x86-304.43.run
 - sudo sh $HOME/Downloads/NVIDIA-Linux-x86-304.43.run

To install for 64-bit Ubuntu:
 - sudo chmod +x NVIDIA-Linux-x86_64-304.43.run
 - sudo sh $HOME/Downloads/NVIDIA-Linux-x86_64-304.43.run

When prompted in the setup to generate the Nvidia settings or xorg.conf file, click "No". You should be able to use the same settings you already had before installing the newest version of this driver.

Now we can restore our previous settings file:

 - sudo cp /etc/X11/xorg.conf.NVIDIA /etc/X11/xorg.conf

And finally, reboot one last time:

 - sudo reboot

Once the either the Nvidia drivers or Unity get updated to resolve this bug, then just re-enable the Ubuntu-X team PPA and run the following to install the current driver:

sudo apt-get install nvidia-common nvidia-current nvidia-settings

Hope this helps. Just remember to keep tabs on when the next driver is released because you will have to run the previous command manually to get it back from the Ubuntu-X team PPA.