Positioning QDockWidgets has no effect

#include <QtWidgets>
#include <QtGui>

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

    QMainWindow window;
    window.resize(QSize(300, 300));
    window.move(QPoint(100, 100));

    QDockWidget *dock = new QDockWidget(&window);
    dock->setAllowedAreas(Qt::AllDockWidgetAreas);

    window.addDockWidget(Qt::TopDockWidgetArea, dock);
    dock->resize(QSize(50, 50));
    dock->move(QPoint(200, 200));
    dock->setFloating(true);
    window.show();

    return a.exec();
}