When I have pidgin running and I lock the screen and unlock again, an
appindicator item with no icon is added to the top panel. I can tell
this blank indicator is present because a mouseover highlights it, as
is normal for appindicator that do have icons. This blank indicator
does everything the same as the pidgin indicator (show/hide pidgin on
left click, pidgin context menu on right click). This blank indicator
is never deleted. Over successive lock/unlock cycles more blank
indicators are added and eventually all the other items on the GNOME
shell top bar are pushed off the screen making them unusable. This
issue is a regression from bullseye, but I'm not sure if GNOME shell or
the appindicator extension is responsible for it.

There are two workarounds for this issue:

 * Close all apps, log out, log in, open all apps.
 * Open Looking Glass, select blank indicator, .destroy() it.