When a top-level widget has a graphic effect applied,
QWidgetPrivate::clipToEffectiveMask() must not use the parent widget for
the mask calculation as this prevents the loop below from bailing out in
the first loop (w->isWindow()) and might mess up the clip region when
there is a widget with a mask in the parent chain.
Fixes: QTBUG-131893
Change-Id: I5d5777e730bee309db21ad5eb65387d19321ee6c
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 49f462b7f873ecba6bb205697338a4f1eef6d307)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit b33821736008580ad9b13c005a06d498d4eb1d9a)
034bc2fe10