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> if I did not lock the prefs.js
I just read up on this. It seems like locking is temporary and all you need to do to reverse it, is delete the lockfile.
> I will use https://jm42.github.io/compare-user.js/ for about:config modifying.
These might be useful to you:
https://pastebin.com/pdEbeX1m
Full list of all prefs defined in Mozilla's source code for 52. Some of them are hidden/ i.e not set in about:config so there'll be no way to know about them. And: http://kb.mozillazine.org/About:config_entries
Is a nice util for quickly finding out what each does, and available settings.