[Merge] lp:~unity-team/qtubuntu/revert-occlusion-detection into lp:qtubuntu

[Michael Zanetti]

I've tested this along with the related qtmir branch and couldn't reproduce the issue any more so far.
-- 
https://code.launchpad.net/~unity-team/qtubuntu/revert-occlusion-detection/+merge/277048
Your team Ubuntu Phablet Team is requested to review the proposed merge of lp:~unity-team/qtubuntu/revert-occlusion-detection into lp:qtubuntu.