QcomboBox draws focus frame even when setting Qt::WA_MacShowFocusRect to false

When creating an editable combobox and calling 

setAttribute( Qt::WA_MacShowFocusRect, false );

the focus rect is still drawn. This is particularly annoying when you want to combine the combo box with e.g. the buttons from a QSPinBox to create a widget akin the stroke width widget of illustrator.

An almost trivial solution would be to honour the attribute when drawing and to set it to true in the QComboBox constructor for backward compatibility.