this is the oldest (longest-used) add-on in my Firefox which is still installed.

I remember having a bliss to use this add-on instead of manually editing XMLs and starting a local web server so Firefox recognizes them.

I don't have it enabled all the time but from time to time I still enable it to add a search engine. A shame this is a hassle to do in Firefox without, other browsers I use don't have such problems. Also it's sad there is no easy way to edit a search after it's added, without re-adding it with the edits.