PR Summary

There is currently an issue with the slider value Text, because it is placed outside the Axes, and can be of arbitrary length, so I don't know how to get the 'potential' Bbox of it in order to capture the right background. So this is draft for now. For the time being, I have added a comment that users should set a fixed-width format string, but perhaps we need to change the default to a tick formatter that will be fixed width.

PR Checklist

Tests and Styling

• Has pytest style unit tests (andpytest passes).
• IsFlake 8 compliant (installflake8-docstrings and runflake8 --docstring-convention=all).

Documentation

• New features are documented, with examples if plot related.
• New features have an entry indoc/users/next_whats_new/ (follow instructions in README.rst there).
• API changes documented indoc/api/next_api_changes/ (follow instructions in README.rst there).
• Documentation is sphinx and numpydoc compliant (the docs shouldbuild without error).