Only show apps that log to zg in Exclude Application chooser

[Jeremy Bícha]

The Exclude Application chooser appears to include all .desktop's including many that don't make sense like:
- Python v2.7
- Network Connections
- Compiz
- GNOME Shell Classic
- View File
- Window Manager

I think it would be better for users to only have relevant apps show up in this list.

GNOME 3.8 has a new Notifications panel in Settings that allows users to customize GNOME Shell notifications. Apps show up there either because they've explicitly opted in (see https://wiki.gnome.org/GnomeGoals/NotificationSource ) or because they've shown at least one notification.

Zeitgeist could do something similar. Show apps in this list once one event has been logged from the app. And also make a way for app developers to signal to zg that they log to zg even before they have logged one event.

[Manish Sinha (मनीष सिन्हा) (manishsinha)]

The best way I can come up is this

AllApps = All apps which have a desktop file
AppsWithNoDisplayTrue = Apps which have desktop file containing the key NoDisplay=true
AppsAlreadyLogged = Apps which have already logged atleast one event
AppsInDsRegistry = Apps which have their actor set in atleast one of the templates of DataSourceRegistry

The correct app list should be

(AllApps minus AppsWithNoDisplayTrue) union AppsAlreadyLogged union AppsInDsRegistry

This is closest to solution but would be good to have a CheckBox

[ ] Show all applications which will show items in AllApps