As you can see on the picture the listbox features a fully equipped scrollbar in normal mode:
But if I switch into the normal mode the arrows and the slider are missing:
Nonetheless the scrollbar is there and it is working - it's just not rendered - I know that because I can click into the scrollbar area and scroll. After clicking a while the scrolling stops because the virtual slider moved under my cursor. If I then move to some end of the scrollbar area I can move forward or backward.
I'm using QV 11.20 SR7 64bit on Windows 7 by the way.