QToolTip: rounding the corners with a style sheet does not work correctly

Styling a QToolTip with rounded corners using style sheets will round the corners, but will not leave the corners transparent. You will still see the squared shaped widget underneath.

QToolTip

{background-color: red;border-style: outset;border-width: 2px;border-radius: 10px;border-color: beige;font: bold 14px;min-width: 10em;padding: 6px;}