Comment 1 for bug 1620728

Looking at the changelog it looks like the culprit has landed in:

```
 -- Marco Trevisan (Treviño) <mail@3v1n0.net> Sat, 06 Aug 2016 16:25:58 +0000

unity (7.5.0+16.10.20160727-0ubuntu1) yakkety; urgency=medium

  [ Andrea Azzarone ]
  * [LockSceen] Remove numlock warning. (LP: #1526322)
  * Make sure initiate and terminate callbacks are not empty before
    calling them. (LP: #1605012)
  * Properly destroy close_button_ to properly disconnect lambda. (LP:
    #1605010)
  * Use the standard notification-device-eject in the "device eject"
    notification. This allows us to scale it properly on high-dpi
    setups. (LP: #1605231)
  * Add tools to enforce unityshell plugin for the current profile and
    add "move" and "resize" plugins as requirements. (LP: #1506023,
    #1605007)
  * When locked discard damages from windows below lockscreen. (LP:
    #1605180)

  [ Eleni Maria Stea ]
  * DecoratedWindow: Added shadows for shaped windows

  [ Marco Trevisan (Treviño) ]
  * LockScreenAcceleratorController: ensure callbacks are valid before
    calling them (LP: #1605012)
  * DecoratedWindow: Cleanup shadows for shaped windows, reduce
    recomputation
```