QCocoaScreen::grabWindow doesn't work with Retina display to the right of the main display

#include <QtGui>
#include <QtWidgets>

QString text = R"foo(
Any other combination of encoding prefixes may or may not be supported by the implementation. The result of such a concatenation is implementation-defined.
String literals have static storage duration, and thus exist in memory for the life of the program.
String literals can be used to initialize character arrays. If an array is initialized like char str[] = "foo";, str will contain a copy of the string "foo".
The compiler is allowed, but not required, to combine storage for equal or overlapping string literals. That means that identical string literals may or may not compare equal when compared by pointer.
)foo";

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QWidget win;
    win.setWindowTitle("Hello");
    win.setLayout(new QVBoxLayout);

    auto label = new QLabel(text);
    label->setWordWrap(true);
    win.layout()->addWidget(label);

    auto btn = new QPushButton("Hit Me!");
    win.layout()->addWidget(btn);

    qDebug() << QApplication::desktop()->windowHandle()->frameGeometry() << QApplication::desktop()->mapToGlobal(QPoint(0,0));

    QObject::connect(btn, &QPushButton::clicked, [&win](bool){
        auto window = win.windowHandle();
        auto screen = window->screen();
        auto r = window->frameGeometry();
        auto img = screen->grabWindow(QApplication::desktop()->winId(), r.left(), r.top(), r.width(), r.height());
        static QString f = "untitled.png";
        f = QFileDialog::getSaveFileName(&win, "Save File", f, "Images (*.png *.xpm *.jpg)");
        if(f.size()) {
            img.save(f);

            img = screen->grabWindow(QApplication::desktop()->winId());
            img.save(QFileInfo(f).dir().absoluteFilePath("full.png"));
        }
    });

    win.show();

    return a.exec();
}