Finish customize system button pos for QtWidgets

SineStriker

2023-12-27 2f2ee6571e9ce784db0488ade60816f09bd7448c

 src/widgets/widgetwindowagent.h

@@ -26,6 +26,7 @@
        QWidget *systemButton(SystemButton button) const;
        void setSystemButton(SystemButton button, QWidget *w);

        // Not implement, don't use now
#ifdef Q_OS_MAC
        QWidget *systemButtonArea() const;
        void setSystemButtonArea(QWidget *widget);