What I can’t understand is how hard it can be to implement both a tiny scrollbar and a normal size scrollbar at the same time.
Have the tiny scrollbar default when looking at the main gui with all default windows. Then when you hoover your mouse close to the area of the tiny scroll bar let the normal scrollbar appear from 100 transparency to 0 in 500 ms or whatever seems to be the natural time flow. When the scrollbar is normal size it can be used to scroll just like if it was implemented and visible as default. When hoovering away from the normal scrollbar it dissapears and gets transparent in 500 ms.
Problem solved.