User-Agent:       Mozilla/5.0 (X11; Linux x86_64; rv:18.0) Gecko/20100101 Firefox/18.0
Build Identifier: 

Sometimes the screensaver gets into a state where it is impossible to hide the clock using the keyboard (have to been dragged away with the mouse) and after unlocking the screen stays blank as if it still is locked.

Alt-Tab kind of works, showing the open applications. But no applications is shown on the screen.

In this state Alt-Tab also brings up the running applications while the screen is locked and the clock is displayed.

I suspect it happens when there is some other application grabbing the keyboard or mouse, as it's most frequently seen when running kvm virtual machines or playing games.

Reproducible: Sometimes

Steps to Reproduce:
1. Not sure. Probably run some application grabbing the keyboard such as a kvm virtual machine.
2. Wait for the screen to lock
3. Try to unlock
Actual Results:  
Grey blank "locked" screen after successful unlock.

hard to get rid of the clock overlay.

Expected Results:  
Screen successfully unlocked and access to running applications again.