Slider Tickmarks Layout

Hello,

I am trying to put some simple labels under/over a slider with tickmarks. However, I have some problems of accurately aligning labels to the ticks. In particular, the tickmarks are offset from the two endpoints of the slider. Is there a good (ideally platform independent) way to figure out the position of the first/last tickmark within is widget ? In the default Mac OS 10.6 style it seems both are offset by 9 pixels. I have tried to query things like QStyle::PM_SliderThickness and company but I am either querying the wrong style or these do not have the information I need. I am new to Qt so I am wondering whether there is an easy way to figure this out or whether there are inherent reasons why this should/cannot be easily determined in a general way.

Thanks in advance for any hint