I know that there is something like it, but I am definitely not being able to find it anymore

Anyone knows this "extension", and where can I get it?

(I mean, more specifically than "the internet")

I'm not asking anyone to do the search for me, it's just that I'v been searching for a while now, and it was hard to find by the first time already... and maybe someone around here knows/uses it...

(PS.: Mods, I apologise for the copy of the topic.... was accidental... opera browser allows to go back in a manner that no other browers usually do, I was distracted and thought I was editing the post, when in fact I went further back to the original posting page, rather than its prior edit page...)