If you want to prevent users from messing around with your beloved and perfectly customized Firefox install, you can now add a simple deterrant with Public Fox, developed by Igor Rashnistov.

Public Fox lets you set a password to lock some configuration including the Options window, about:config (Firefox’s advanced preferences), the Add-Ons manager (so it prevents adding extensions and themes), the Bookmarks Manager, adding bookmarks, the download manager and also set file extensions you want to block, like .exe, .bat or .msi files, which can be used to install unwanted applications or even spyware.

And Public Fox was smart enough to block the selected windows even when I tried to access them from the location bar directly (with a chrome:// URL).

Public Fox is not perfect, and its protection can be circumvented by starting Firefox in safe mode or with a new profile but it should be enough to stop most users.

I couldn’t access about:config after trying several times with the correct password (it worked for other windows), as well.

Despite these minor problems it is a helpful transparent extension you would like to try.