[REG] border-radius

The following css does not work anymore :
QPushButton
{
min-width:90px;
height:26px;
border-image:url(picture.png) 1 1 1 1 stretch stretch;
border-radius:8px;
}

button is rounded in Qt 4.5.3, and is square with Qt 4.6.x, seems that border-radius is simply ignored.
however, border-radius works well when applied to a QLabel instead of a QPushButton