Summary:
Remove all instances of anchors in a layout.
This is undefined behaviour (even if it happens to work) and results in
a warning in 5.11.
Resulted in some shuffling about, but generally cleaner code.
Visually looks the same
Test Plan:
Added some buttons
Dragged and dropped some buttons out of the top header
Still got my "drop here to remove button" hint with the same opacities
Reviewers: #plasma, broulik
Reviewed By: #plasma, broulik
Subscribers: kwin, #kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D12284
52e42df9d6