OSX: styling problem in QToolBar if setUnifiedTitleAndToolBarOnMac() is set

when a window is set to setUnifiedTitleAndToolBarOnMac(true) and a QCheckBox is added to the QToolBar of this window, the checkbox text is bold while the toolbar is docked and the style property "font-weight" does not work.
if setUnifiedTitleAndToolBarOnMac is not set or if the toolbar is floating the checkbox text is normal and styling works as expected.