How to create hidden Firefox Extension?

Question

Is it possible to create Firewox extension that will not shown in Extensions List? And so cannot be deinstalled manually?

Answer 1

See this mozillazine entry and this forum entry. These extensions are somehow installed via the registry and supposed to be malicious - so there's no use for this except if you want to be on some malware blacklist.

For private use or administration use like MSalters suggested in his comment, "hidden" (for some users) extensions could be useful, but this should be implemented by Mozilla first.