Problem with QSizeGrip under OSX

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I wanted to make a QRubberBand instance user resizeable after an initial selection has been made. After tinkering a bit myself with QSizeGrip myself and having no success, I asked a question over on stackoverflow. A kind person answered and then even posted a complete example project: "Implementing resize handles on QRubberband":http://stackoverflow.com/a/19067132/840992

Part of the suggested solution:
@Resizable_rubber_band::Resizable_rubber_band(QWidget parent) : QWidget(parent) {
//tell QSizeGrip to resize this widget instead of top-level window
setWindowFlags(Qt::SubWindow);
QHBoxLayout layout = new QHBoxLayout(this);
layout->setContentsMargins(0, 0, 0, 0);
QSizeGrip* grip1 = new QSizeGrip(this);
QSizeGrip* grip2 = new QSizeGrip(this);
layout->addWidget(grip1, 0, Qt::AlignLeft | Qt::AlignTop);
layout->addWidget(grip2, 0, Qt::AlignRight | Qt::AlignBottom);
rubberband = new QRubberBand(QRubberBand::Rectangle, this);
rubberband->move(0, 0);
rubberband->show();
}

void Resizable_rubber_band::resizeEvent(QResizeEvent *) {
rubberband->resize(size());
}@

The issue is that when I run it (Qt 5.1.1 on OSX) I am still not getting the resize handles. I've searched around and haven't found anything about issues or bugs with QSizeGrip on OSX so I thought I would ask here before I waste more time on this approach. Has anyone used QSizeGrip successfully under OSX? Any glaring issues with the example?