React: onMouseEnter lost when hovering over children

[mmellado]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
When a onMouseEnter event is triggered on an element, the event is lost when the mouse comes over a child rendered based on this event. This didn't happen in React 15, where hovering over the newly created child would persist the event.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://jsfiddle.net or similar (template for React 16: https://jsfiddle.net/Luktwrdm/, template for React 15: https://jsfiddle.net/hmbg7e9w/).

React 15 (expected behavior): https://codepen.io/anon/pen/mBKmzN
React 16 (same code): https://codepen.io/anon/pen/NazjBN

To reproduce, hover anywhere in the red. Then when the menu opens, try to hover anywhere with blue background.

What is the expected behavior?
Hovering over the newly created child element should persist the onMouseEnter event

Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?
Testes with React 16 on Chrome/Linux (latest Ubuntu Mate), have not tested anywhere else

[gaearon]

This the same as #10906 and #11152, and was fixed in https://github.com/facebook/react/pull/11164.
We’ll release a fix soon.

[gaearon]

React 16.1.0-beta has been released. Please update react, react-dom, and react-test-renderer (if you use it) to this version and let us know if it solved the issue! We’d appreciate if you could test before Monday when we plan to get 16.1.0 out.

[mmellado]

Tested with React 16.1.0-beta. Seems to be fixed for all my reproducible use-cases :)