You can use the KeyConfig add-on to remap the F12 key.

Banban said

You can use the KeyConfig add-on to remap the F12 key.

Thanks, but as I wrote in my first sentence, "I know already that the solution is to install an addon, but I try to limit the addons because I want my Firefox clean."

The main question was, can I delete all the devtools.* entries in about:config? It will never happen I use them in a thousand years' time. Or, can I change one of them to avoid the F12 behaviour?

Indeed, I didn't notice your first sentence, sorry…

No, you can not remove devtools.* entries in about:config. If you meant to modify prefs.js, actually this file stores only changed prefs (different from default values), not all prefs inf about:config. And even you could remove devtools.* lines from about:config, it is just settings, not the behaviour of core features like the developer tools panel and its hot key.

If you have technical skills, you could try to find how KeyConfig works (from the source code) and maybe reproduce yourself the corresponding changes in Firefox. (I have no idea if it is possible, but why not?)

Thanks Banban for your quick response.

I have a few technical skills (not many though) and I'll try to have a look (maybe). For now I'll just use an addon, as you suggested. I found one that does exactly that, disabling the F12 key, and nothing else, just killing it and no other options: I saved it a couple of days ago in the favourites and I'll give it a try.

I just realized that I am barking at Firefox, but apparently this F12 hotkey is also used in Chrome, and.. Internet Explorer! It is one of those useless keys for the most, perhaps I should make it die in the same way I did with the Ins key: I'll take it off with a flat screwdriver, and bin it. Like Ins (and Pause, Scroll lock, Numlock that is always on anyway) I don't remember pressing F12 ever, apart from when I pressed it by mistake...

OK, good luck if you try that. Thanks for your feedback.

Thanks!