How to properly code Oxygen-compatible paint events for QFrame-derived widgets?

[Hans Meine]

Hi,

is there documentation somewhere how to properly draw in QFrame-derived 
widgets in order to fill the the sunken area within the round corners
a) completely (normally, you get "ugly" 1px borders due to the rounded
   corners), and
b) ideally without painting over the focus glow?

Is this possible at all, or does it need help from the Oxygen style?
Should I read up on how to draw styled frames myself (i.e. without 
QFrame::paintEvent)?

Have a nice day,
  Hans