Corner widget in QTabWidget doesn't show up

[ePharaoh]

The corner widget in a QTabWidget doesn't render at all.
I have tried to use QToolButton and QLabel.

{
    QTabWidget tw;
    QLabel *label = new QLabel("foo");
    tw.setCornerWidget (label);
}

{
    QTabWidget tw;
    QLabel *label = new QLabel("foo");
    tw.setCornerWidget (label);
}

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Simple enough, and I do see a little extra space at the beginning of the tab-list, but nothing is rendered there.