We started with updating our client to ReactJS, which we do in small steps (so we do not break the client). One part of this is the way widgets work. This widget is build by R&D and is a first step to our new way of building widgets in a ReactJS approach. This approach is not meant for customers/partners yet, but we working hard to make the new way of building custom widgets more fun, easy and less error prone. When its possible, we will also inform the community and release alpha/beta releases so that you can provide feedback.
It looks like a react widget, but abandons the openess of Mendix widgets. The code is obfuscated and pretty complex.