Why not keep your FPS up?

This mod added an "Never" option to vanilla's "Inactivity FPS Limit", which the author maybe unable to imagine why someone would need this.

But there is it, why or why not?

Just do it.

Original Intention

The author wants to test out if mixin & mixin extras could be written in Kotlin practically, so here it comes.

Basically, I tried some ways and hacks to complete it, adding compiler flags, for example.

And I finally found a way out achieving this.