Created attachment 84150 [details]
Video illustrating the problem with Systemsettings tooltips

When using save intermediate rendering results in Blur effect one can observer rendering problems during the fade out of blurred windows.

Steps to reproduce:
1. Set animation speed to very slow to properly observe
2. Enable blur with save intermediate rendering results
3. Open Systemsettings
4. move the mouse around to show and hide tooltips

Expected Results:
Normal fade in and fade out

Actual Results:
Ugly tearing effects. See attached video. The video doesn't capture the complete tooltips. Please ignore the cut-off part. The parts of the tooltips which are captured show the problem.

Workaround:
Disable save intermediate rendering results in blur effect

The problem is both present in 4.11 branch and master branch. The video is recorded with 4.11 branch.