PR Summary

Addresses #21394 so that the padding is consistent, if not exactly what the user wants.

fig, axs = plt.subplots(2, 1, sharex=sharex)
axs[0].set_title(f'A sharex={sharex}', pad=-40)
axs[1].set_title('B', pad=-40)

Old

Note how when we sharex the title is displaced downwards, but only in the first plot, not the last one. This is inconsistent with the sharex=False behaviour, which is to manually move the axes outside the axes bounds (regardless of the users' pad argument).

We did discuss this behaviour, and decided it was OK, if less than great. Users can get around this by specifying y manually (i.e. y=1.0001 works fine). We probably should deprecate the pad argument in favour of just asking folks to specify the title position using y.

New

PR Checklist

• Has pytest style unit tests (and pytest passes).
• Is Flake 8 compliant (run flake8 on changed files to check).
• New features are documented, with examples if plot related.
• Documentation is sphinx and numpydoc compliant (the docs should build without error).
• Conforms to Matplotlib style conventions (install flake8-docstrings and run flake8 --docstring-convention=all).
• New features have an entry in doc/users/next_whats_new/ (follow instructions in README.rst there).
• API changes documented in doc/api/next_api_changes/ (follow instructions in README.rst there).