ipywidgets 7.7.0 is now released on Pypi, soon on conda-forge. This release brings several bugfixes and feature enhancements, including an optional way to synchronize widget state across multiple frontends. See the changelog at ipywidgets changelog — Jupyter Widgets 7.7.0 documentation
Also, we have released 8.0.0rc0. We encourage people to test this release candidate and report issues.