Document how to get custom TabPanel working
Document how to get custom TabPanel working

This is not documented, only learnt about it from https://github.com/reactjs/react-tabs/issues/99#issuecomment-441160045 (which also is not easy to find as it is part of a "derailed" issue thread).
reactjs/react-tabs,mzabriskie/react-tabs,reactjs/react-tabs,rackt/react-tabs