JLab remix

[martinRenou]

This builds upon #119

It's still very much in progress

[github-actions]

👈 Launch a Binder on branch martinRenou/jupytercad/app

[martinRenou]

@jtpio I'm opening this early to get some feedback from you on the approach.

I'm struggling to make a custom MainMenu in https://github.com/QuantStack/jupytercad/pull/120/files#diff-1f52c6c256b9d1ac999449f7408fa02a5d78de5489933d5c1a87326840225445
My previous versions that were not building upon JupyterLab 4 beta were working with the old way of making menus, but now my menu does not work anymore. It does not show up in the resulting app and I'm out of ideas. I could really use your eyes on this!

[jtpio]

Thanks @martinRenou I'll have a look. It's possible there could an issue / breaking change in lab 4.

That reminds me of an issue related to Menus when updating Notebook to a lab pre-release: jupyter/notebook#6757 (comment). Although it does not look the same issue exactly.

[martinRenou]

Closing as replaced by Trung's PR