The previous application monitoring code was originally designed
to be based on WM_CLASS, which was then resolved on a server.
We have that resolution code locally now, so instead
of saving WM_CLASS data, save application IDs.
Also, inside the WM we have a much better
infrastructure for tracking windows. In particular, rather
than polling, we can just watch for focus notification on
the display, and window add/remove.
Instead of polling XScreensaver, use DBus to watch org.gnome.Session
which already has an idle time watch.
Now there is no polling at all inside the monitor.
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