Sending enter and leave events to other windows than the grabbing
window is not logical. The policy should be that only the grabbing
window receives enter and leave events.
Changed the documentation accordingly and provided the necessary
changes to Windows implementation.
Also removed explicit leave event generation for widgets when
popup is opened as that is now redundant.
tst_QWidget::underMouse() test was changed to behave according to
new logic.
Task-number: QTBUG-27871
Change-Id: I127fb8685b4a4206d1a319f42cba491ec02bc8ca
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
b8be2e67ea