Summary:
Mostly meant for multi-screen setups: we don't want that a strut set on
a window on screen 0 results in screen 1 completely being excluded. Even
if that's strictly seen a client bug, it's better to just ignore the
strut from KWin's side.
The sanity check is implemented in Client::adjustedClientArea.
From a pure standard point of view this change is a EWMH violation and
thus can cause regressions: struts by clients no longer working.
A test case for struts is added, including some invalid combinations
whose strut is ignored with this change.
Reviewers: #plasma
Subscribers: plasma-devel
Projects: #plasma
Differential Revision: https://phabricator.kde.org/D1386
