window->isActive() always returns false for QWindow::fromWinId()

That's an obstacle for the keyboard focus.

The use case is the integration of a QtQuick GUI into existing OpenGL application by using the QQuickRenderControl. The QQuickWindow is rendered into the QWindow obtained from QWindow::fromWinId().

Keyboard input focus doesn't work because there is no focused window: QGuiApplication::focusWindow() == 0.

If either QQuickWindow or foreign window could make it to be the focus_window of the application, the input events through QCoreApplication::sendEvent() would trigger a correct behaviour in QQuickWindow.