No changes to the core needed,
no dependent modules.
Tested on Mage 1.2-1.7.
Lots of code, but small amount of Mage key code,
so it should work on future releases too.
It was a dream of many, but some were not capable to build this extension,
and some were too lazy to do it.
I just needed it more than others I guess.
I've spent a lot of time to build it, so I want to share it with community.