The other day I wrote about what "AppIndicator" is (a protocol) and some things about how the Cinnamon desktop appeared to support it, except they weren't working for me. Now I actually understand what's going on, more or less, and how to solve my problem of a program complaining that it needed AppIndicator.

Cinnamon directly implements the AppIndicator notification protocol in xapp-sn-watcher, part of Cinnamon's xapp(s) package . Xapp-sn-watcher is started as part of your (Cinnamon) session. However, it has a little feature, namely that it will exit if no one is asking it to do anything:

XApp-Message: 22:03:57.352: (SnWatcher) watcher_startup: ../xapp-sn-watcher/xapp-sn-watcher.c:592: No active monitors, exiting in 30s

In a normally functioning Cinnamon environment, something will soon show up to be an active monitor and stop xapp-sn-watcher from exiting:

Cjs-Message: 22:03:57.957: JS LOG: [LookingGlass/info] Loaded applet xapp-status@cinnamon.org in 88 ms
[...]
XApp-Message: 22:03:58.129: (SnWatcher) name_owner_changed_signal: ../xapp-sn-watcher/xapp-sn-watcher.c:162: NameOwnerChanged signal received (n: org.x.StatusIconMonitor.cinnamon_0, old: , new: :1.60
XApp-Message: 22:03:58.129: (SnWatcher) handle_status_applet_name_owner_appeared: ../xapp-sn-watcher/xapp-sn-watcher.c:64: A monitor appeared on the bus, cancelling shutdown

This something is a standard Cinnamon desktop applet. In System Settings → Applets, it's way down at the bottom and is called "XApp Status Applet". If you've accidentally wound up with it not turned on, xapp-sn-watcher will (probably) not have a monitor active after 30 seconds, and then it will exit (and in the process of exiting, it will log alarming messages about failed GLib assertions). Not having this xapp-status applet turned on was my problem, and turning it on fixed things.

(I don't know how it got turned off. It's possible I wen through the standard applets at some point and turned some of them off in an excess of ignorant enthusiasm.)

As I found out from leigh scott in my Fedora bug report , the way to get this debugging output from xapp-sn-watcher is to run ' gsettings set org.x.apps.statusicon sn-watcher-debug true '. This will cause xapp-sn-watcher to log various helpful and verbose things to your ~/.xsession-errors (although apparently not the fact that it's actually exiting; you have to deduce that from the timestamps stopping 30 seconds later and that being the timestamps on the GLib assertion failures).

(I don't know why there's both a program and an applet involved in this and I've decided not to speculate.)