Summary:
In wayland, QScreen::availableGeometry() returns QScreen::geometry(), we could get a better value from plasmashell
BUG: 386114
Test Plan: Krunner isn't overlapped by a top panel in all cases
Reviewers: #plasma, davidedmundson
Reviewed By: #plasma, davidedmundson
Subscribers: meven, apol, plasma-devel
Tags: #plasma
Differential Revision: https://phabricator.kde.org/D27458