Fix clamping in screenContainsPos (cherrypick)
QRect.contains(somePointF.toPoint()) will round the values.
This is problematic for the case of a mouse being at -0.4, we will consider it in bounds for the screen, but obviously this doesn't match any surfaces.
The detection and confineToBoundingBox need to behave the same and floor.
(cherry picked from commit e924b1cb)