Add notification observer on Mac

SineStriker

2023-12-27 88b5b56b6a67d93208eae3980af2f30da09dd8ae

 src/widgets/widgetwindowagent.cpp

@@ -36,12 +36,10 @@
        w->setAttribute(Qt::WA_DontCreateNativeAncestors);
        w->setAttribute(Qt::WA_NativeWindow);

        if (!d->setup(w, new WidgetItemDelegate())) {
            return false;
        }
        d->setup(w, new WidgetItemDelegate());
        d->hostWidget = w;

#ifdef Q_OS_WINDOWS
#if defined(Q_OS_WINDOWS) && QWINDOWKIT_CONFIG(ENABLE_WINDOWS_SYSTEM_BORDERS)
        d->setupWindows10BorderWorkaround();
#endif
        return true;