Hacker News Reader

is there a good list of those prefs? or perhaps I can scan source code for some string

Frankly, these secret prefs are basically either:

- prefs that a developer was too lazy to add to the list of pref; or - prefs that serve only during automated tests.

You could scan source code for `Services.prefs` and `nsIPreferenceService` if you really want to find them.