Deprecate "return false" in event handlers

[sophiebits]

We currently support this, but it makes code less understandable and we'd like to stop supporting it and encourage people to use either e.preventDefault() or e.stopPropagation() as appropriate.

[chenglou]

👍
And then free up the event handler's return value for something else.

[syranide]

@chenglou https://github.com/reactjs/react-future/blob/master/06%20-%20Returning%20State/01%20-%20Stateful%20Functions.js you mean? :)

[chenglou]

Maybe =)
Otherwise we can always use it to indicate something in a potential future event system.