Qt VerticalTitleBar DockWidget with styleSheet doesn't work

Qt VerticalTitleBar DockWidget with styleSheet doesn't work

The problem is, with a vertical title bar on a dockwidget, the title text
is only partialy visible if I use a styleSheet.
in my dockWidget I do
features = self.features()
features = features | QtGui.QDockWidget.DockWidgetVerticalTitleBar #
self.setFeatures(features)
self.setWindowTitle("myTitle")
with only this, I have my dockWidget with my title visible, but if I add
some styleSheet on the subControl Title
QDockWidget { background-color:#f9cdcd; }
My title is not entirely visible, we can see only
myT
and I don't know why ? :(
the title is still write verticaly but cut.
this happen both isFloating or not.
pps : I'm on linux openSuse
Thanks for your Help.