Updating jupyterlab-fonts to interact with the new JupyterLab settings editor

[isabela-pf]

With the addition of a JupyterLab settings editor, jupyter-lab fonts seems like it could fit with core JupyterLab in some new (and exciting!) ways. I'd be interested in seeing jupyterlab-fonts

• as an extension section in the JupyterLab settings editor (instead of their current placement in the menu bar)
• somehow appearing in/linking to the jupyterlab-fonts settings section as overrides in any place in the settings editor where the theme is referenced they (to avoid confusion from conflicting information)
• bonus points if adding other non-font theme editing parameters could also appear here

Does this sound like an update this project would be interested in making?

(cc: @tonyfast)

[bollwyvl]

Welp, "this project" is, welp... me. So yes, i think it would be a fine thing to look into. The challenge is, while JSS is a fairly straightforward, it would be rather harder to construct valid queries for lot of things. CSS (well, JSS + plugins) selectors are... quite varied.

A quick win might be to enumerate a bunch of commonly used things in that oneOf... but it's still going to be hard to create enough control surfaces to describe make the background red of a buttons inside cells when on a mobile device in presentation mode.

I haven't had a chance to kick the tires on the new editor (specifically how it could be customized), but it would be reasonable to have it there. But i'd also like to be able to reuse such an editor for notebook/cell (#47) metadata.

[bollwyvl]

Another win: we can likely scrape a list of all the --jp-* variables, and make semi-sane predictions about what shapes they might fulfill.

[bollwyvl]

I've had another look at this: at present, it's rather hard to specify custom rjsf fields without replacing the entire widget. Perhaps in JupyterLab 4 the situation will be better.