QWindow::activeChanged notification is not consistent with isActive

QWindow::isActive returns true if the window, or any of its ancestors is focused. The activeChanged signal is emitted only on the focused window and not any descendants, so for those windows, the property may change without a notification.

Attached qml file demonstrates the discrepancy - the Window.active property doesn't influence bindings properly, but "force-refreshing" the bindings by a Timer shows the correct value.