Drag drop cursors are broken on Mac

#include <QApplication>
#include <QPushButton>
#include <QLineEdit>
#include <QDrag>
#include <QMimeData>
#include <QHBoxLayout>
#include <QDragEnterEvent>

struct AcceptWidget : public QLineEdit
{
    AcceptWidget(QWidget *parent = 0) : QLineEdit(parent)
    {
        setAcceptDrops(true);
        setReadOnly(true);
        setText("<accepts drops>");
    }

    void dragEnterEvent(QDragEnterEvent *evt)
    {
        // BUG: Displays accept/copy cursor in Qt 4.8.x, but only intermittently in Qt 5.1.x
        evt->acceptProposedAction();
    }

    void dropEvent(QDropEvent *evt)
    {
        setText(evt->mimeData()->text().toUtf8().data());
    }
};

struct DeclineWidget : public QLineEdit
{
    DeclineWidget(QWidget *parent = 0) : QLineEdit(parent)
    {
        setReadOnly(true);
        setText("<declines drops>");
    }

    void dragEnterEvent(QDragEnterEvent *evt)
    {
        // BUG: Displays forbidden cursor in Qt 4.8.x, but nothing in Qt 5.1.x
        evt->ignore();
    }
};

struct DragWidget : public QWidget
{
    Q_OBJECT
public:
    DragWidget(QWidget *parent = 0) : QWidget(parent)
    {
        setWindowTitle("Drag Widget");
        setMinimumSize(400, 100);

        QHBoxLayout *layout = new QHBoxLayout(this);

        QPushButton *pushButton = new QPushButton("Click Me", this);
        layout->addWidget(pushButton);

        AcceptWidget *acceptWidget = new AcceptWidget(this);
        layout->addWidget(acceptWidget);

        DeclineWidget *declineWidget = new DeclineWidget(this);
        layout->addWidget(declineWidget);

        connect(pushButton, SIGNAL(pressed()), this, SLOT(startDrag()));
    }

private Q_SLOTS:
    void startDrag()
    {
        QDrag *dr = new QDrag(this);

        QMimeData *data = new QMimeData;
        data->setText("This is a test");

        dr->setMimeData(data);

        dr->exec(Qt::MoveAction | Qt::CopyAction | Qt::LinkAction, Qt::MoveAction);
    }
};

#include "main.moc"

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

    DragWidget dragWidget;
    dragWidget.show();

    return a.exec();
}