I made this library a while ago, long before all this hype about React's license (which was with the questionable clause from the beginning). I added support for Preact as I liked the minimalistic style of Preact, used it in my own projects and Jason was really responsive solving Preact's compatibility issues. Later on, Dominic asked if I want to add support for Inferno, which I did. I really love that there are different library implementations with compatible API, so you can choose a proper solution based on its pros/cons.

Isn't it the most generic css tooltip style on the internet? (just black tooltip with white text and border-radius)

Nope, it's a pure coincidence as I've made the button style just to record the GIF. As for the tooltip itself, it uses a generic style, but thanks for the link to your project, looks nice :)

It looks like it doesn't. Tabbing through elements to focus on a button with it applied doesn't bring the hint up automatically, which would probably be the best experience here.

That's a good question, thanks! I didn't think about that, but, surely, this functionality should be added. I will try to research what would be the best solution for accessibility.

Have you tried making an alias for react with the library preact-compat in webpack config? It should make a lot of react libraries work seamlessly with preact too.

  import {h, Component} from 'preact'
  import {ReactHintFactory} from 'react-hint'
  import 'react-hint/css/index.css'

  const ReactHint = ReactHintFactory({createElement: h, 
  Component})