QScroller gesture blocks mouse clicks

After commit https://codereview.qt-project.org/c/qt/qtwayland/+/554610/4 ("client: implement QWaylandScreen::topLevelAt()") elements in a QScrollArea can't be clicked anymore if a QScroller with grabGesture QScroller::LeftMouseButtonGesture is used.

To reproduce this issue you can use: https://code.qt.io/cgit/qt/qtbase.git/tree/tests/manual/examples/widgets/itemviews/dirview, you just need to replace in main.cpp line 56:

QScroller::grabGesture(&tree, QScroller::TouchGesture); 
with
QScroller::grabGesture(&tree, QScroller::LeftMouseButtonGesture);