Error bar in QT

Question

I am trying to create Error bar in QT using Box and Whiskers. I get the following plot:

But desired is something like this

Code for box i used is:

QBoxSet *box = new QBoxSet(0);
box->setValue(QBoxSet::LowerExtreme, min);
box->setValue(QBoxSet::UpperExtreme, max);
box->setValue(QBoxSet::LowerQuartile,fres);

The QBoxSet::LowerExtreme is behind the box, how I can move it on top of the box? or is there any other method to do this?