D15821: fix pop up positioning for !compositing mode

[Michail Vourlakos]

mvourlakos added a reviewer: davidedmundson.

REPOSITORY
  R242 Plasma Framework (Library)

REVISION DETAIL
  https://phabricator.kde.org/D15821

To: mvourlakos, #plasma, broulik, davidedmundson
Cc: kde-frameworks-devel, michaelh, ngraham, bruns