Menu does not receive focus in 5.8, when QT_IM_MODULE=ibus

class MyWindow : public QWindow
{
public:
    void keyPressEvent(QKeyEvent *) override
    {
        QMenu menu;
        menu.addAction( "&Menu" );
        menu.exec();
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MyWindow window;
    window.show();
    return a.exec();
}