Prepare to remove style support again

SineStriker

2023-12-22 a5d13e19dd7f6037e10b649c49805922ae5e0fa6

 examples/mainwindow/mainwindow.h

@@ -28,6 +28,7 @@

private:
    void installWindowAgent();
    void installStyleAgent();
    void loadStyleSheet(Theme theme);

    Theme currentTheme{};