When QWindow::alert() is called with a duration of 0, it calls QPlatformWindow::setAlertState(true), and expects the alert state to be reset when the window is next activated. Other calls to alert are ignored while alertState is still true. If alert was called for an active window, it would remain in the alert state until deactivated and activated again, and on some platforms calls to alert would be broken while deactivated. Alerting doesn't make sense for active windows, so we can simply ignore it, which was the behavior with Qt 4 on some platforms. Change-Id: Ia3324da4c89db711b63eb31cddf0bf742bb4e3b8 Found-By: Jan Noertemann <jan.noertemann@uni-dortmund.de> Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com> Reviewed-by: Martin Gräßlin <mgraesslin@kde.org> Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>