add isFixedSize implementation

Yuhang Zhao

2023-12-05 d02f3b0bc32f711bf33a7fd288185963e9e96189

 src/core/corewindowagent_p.h

@@ -16,9 +16,11 @@

        CoreWindowAgent *q_ptr; // no need to initialize

        void setup(QWindow *window, WindowItemDelegate *delegate);
        bool setup(QObject *host, WindowItemDelegate *delegate);

        AbstractWindowContext *m_eventHandler{};
        std::unique_ptr<AbstractWindowContext> context;

        Q_DISABLE_COPY_MOVE(CoreWindowAgentPrivate)
    };

}