win: allow dynamic switch dark mode

Zhao Yuhang

2023-12-22 e33059ee1ef7e1be07490ad0245676ded42589f4

 examples/mainwindow/mainwindow.cpp

@@ -291,6 +291,10 @@
        return;
    currentTheme = theme;

#ifdef Q_OS_WIN
    windowAgent->setWindowAttribute(QStringLiteral("dark-mode"), currentTheme == Dark);
#endif

    if (QFile qss(theme == Dark ? QStringLiteral(":/dark-style.qss")
                                : QStringLiteral(":/light-style.qss"));
        qss.open(QIODevice::ReadOnly | QIODevice::Text)) {