Audacious

I tested 4 different systems and don't see this occurring:

• Qt 5.3.2, xfwm4
• Qt 5.12.7, kwin
• Qt 5.14.2, xfwm4
• Qt 5.15.2, openbox

Maybe it's a specific bug in Qt 5.7?

Could be, but this patch seems to FIX this issue on AfterStep, jwm, fluxbox, and icewm (tested) on both 5.7 and 5.12. The only one it didn't, that I had for testing was on Windowmaker.

If you decide to use the patch but want to be more kosher with it, you could perhaps do it instead as:

        toolbar->show ();
#if QT_VERSION < QT_VERSION_CHECK(5, 8, 0)
        int dock_count = 0;
#endif
        for (auto w : findChildren<DockWidget *> ())
        {
            w->show ();
#if QT_VERSION < QT_VERSION_CHECK(5, 8, 0)
            ++dock_count;
#endif
        }

        /* set initial keyboard focus on the playlist */
        m_playlist_tabs->currentPlaylistWidget ()->setFocus (Qt::OtherFocusReason);

#if QT_VERSION < QT_VERSION_CHECK(5, 8, 0)
        int x = aud_get_int ("qtui", "player_x");
        int y = aud_get_int ("qtui", "player_y");
        if (y <= 0)
                y = 25;

        if (dock_count > 0)
        this->move (x, y);
#endif
    }

    MainWindow::~MainWindow ()
    {
        QSettings settings (m_config_name, "QtUi");
        settings.setValue ("geometry", saveGeometry ());
        settings.setValue ("windowState", saveState ());

#if QT_VERSION < QT_VERSION_CHECK(5, 8, 0)
        aud_set_int ("qtui", "player_x", this->geometry().x());
        aud_set_int ("qtui", "player_y", this->geometry().y());
#endif

        audqt::unregister_dock_host();