Finish customize system button pos for QtWidgets

SineStriker

2023-12-27 2f2ee6571e9ce784db0488ade60816f09bd7448c

 src/core/windowagentbase.h

@@ -24,10 +24,15 @@
            Minimize,
            Maximize,
            Close,
            NumSystemButton,
        };
        Q_ENUM(SystemButton)

        QVariant windowAttribute(const QString &key) const;
        Q_INVOKABLE bool setWindowAttribute(const QString &key, const QVariant &attribute);

    Q_SIGNALS:
        void systemThemeChanged();

    public Q_SLOTS:
        void showSystemMenu(const QPoint &pos); // Only available on Windows now
        void centralize();