[Users] Some icons

[John Jason Jordan]

Claws Mail 3.17.5 on Xubuntu 20.04, up to date, still waiting for the
dist-upgrade availability to 22.04.

There were always several tiny icons in the scrollbar for message view,
each of which would allow me to see things like attachments, etc.
Suddenly they are missing. I have poked through everywhere and I can't
find a way to restore them. What are they called, and how can I get
them back?