custom QRubberBand custom shapes at selection corners

[Talei]

Hello,
I is it possible, with QRubberBand, to draw custom shapes (i.e. squares or circles ) on corner of the selection? ( I have already custom rubberband class and override paint)
Or should do it differently?
I try to make them to allow users to expand selection when clicked and moved.

Best Regards

[Talei]

What I looking for/wanting to implement is something like this (see attachment). I already have "grey" part, but can't figure out how to implement these.

[Lykurg]

Have a look at the book "Foundations of Qt Development" from Johan. There is a small example for that.