4.3

4.3 is a minor release with many bug fixes and improvements.

Highlights:

• API for creating mime-type based renderer extensions using OutputArea.register_mime_type and Notebook.render_cell_output methods. See mimerender-cookiecutter for reference implementations and cookiecutter.
• Enable token authentication by default
• Update security docs to reflect new signature system
• Switched from term.js to xterm.js

Bug fixes:

• Ensure variable is set if exc_info is falsey
• Catch and log handler exceptions in events.trigger
• Add debug log for static file paths
• Don’t check origin on token-authenticated requests
• Remove leftover print statement
• Fix highlighting of Python code blocks
• json_errors should be outermost decorator on API handlers
• Fix remove old nbserver info files
• Fix notebook mime type on download links
• Fix carriage symbol bahvior
• Fix terminal styles
• Update dead links in docs
• If kernel is broken, start a new session
• Include cross-origin check when allowing login URL redirects

Other improvements:

• Allow JSON output data with mime type “application/*+json”
• Allow kernelspecs to have spaces in them for backward compat
• Allow websocket connections from scripts
• Allow None for post_save_hook
• Upgrade CodeMirror to 5.21
• Upgrade xterm to 2.1.0
• Docs for using comms
• Set dirty flag when output arrives
• Set ws-url data attribute when accessing a notebook terminal
• Add base aliases for nbextensions
• Include @ operator in CodeMirror IPython mode
• Extend mathjax_url docstring
• Load nbextension in predictable order
• Improve the error messages for nbextensions
• Include cross-origin check when allowing login URL redirects

See the 4.3 milestone on GitHub for a complete list of issues and pull requests involved in this release.