fix bug windows sometimes don't work in Win7 (#9)

zhuzichu

2023-12-22 6dea61fb21756cb43ec1f065a4395410e60570e8

 examples/mainwindow/mainwindow.h

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

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

    Theme currentTheme{};