Activate the window of the widget under mouse pointer before replay mouse
press event.

Change-Id: I9e699374accf108aa49b2a3c73d5e76631100dfd
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>