GNOME status menu shows rotation lock button
Originally created by @segfault on #11299 (Redmine)
I found this superuser.com post which explains what this additional
button in my GNOME status menu
is:
http://superuser.com/questions/830356/gnome-3-14-system-menu-new-button
So it seems that it’s the “rotation lock”. I have this button at least on two different laptops, which both do not show this button in my other Debian (Stretch) with GNOME shell. Maybe this was fixed in GNOME between Jessie and Stretch.