In 21.0 beta 39, I have my scrollbar placement bottom_left.
If I run vm, then my frame expands by the width of the vm toolbar
(which is placed on the left). When I quit vm then my scrollbar ends
up in the same place as when vm is running, and I have about an inch
of blank space to the left of it. If I resize the frame, then the
scrollbar returns to the correct place.
-- Paul