Bug 371219

After launching a game that blocks compositing:
- Plasma panels go greyish most of the times.
- Plasma is visually frozen -clock is frozen, apps in the task list remain as icon even after closing app.. But plasma is not frozen - it can be interacted with, you can click the clock to get the calender and so on.. 
- Plasma content reverts to the content of the first time it happened: Say you launch a game - plasma visually freeze, then close the game -delete some widgets, start new game -old widgets appear -but only visually - eg. they don't interact - like you are seeing an old kwin buffer or something - (so might be a kwin bug..).

Reproducible: Always

Steps to Reproduce:
1. Enable "Allow applications to block compositing"
2. Start game that blocks compositing (like springrts).

Actual Results:  
Plasma visually goes in to stasis.

Expected Results:  
Plasma should get updates to the screen buffer.

System information: Intel i7-6950x, Nvidia gtx970, 32gb ram, 64bit Arch Linux, dual monitor setup.