the notebooks in examples/ badly need an update

[parmentelat]

related to a comment in mwouts/jupytext#1126

the sample notebooks in examples/ and in particular examples/README.ipynb have been copied as-is from the defunct RISE extension originally targetting nb classic, i.e. https://github.com/damianavila/RISE

these could use an update in order to reflect the actual capabilities of this jupyterlab equivalent,
that at first sight differ from its ancestor on multiple aspects, at least:

• the way to manage the slides metadata
• support for css (check if still available ?)
• header-footer (check if still available ?)
• support for reveal.js features like chalkboard (does that still work) ?

and probably more...

[enury]

The RISE extension is such a nice and useful feature, thank you for maintaining it for jupyterlab 😍

It would be great to have some examples of how to manage the metadata!

I have an old notebook that I would like to reuse in a class, and I notice that the theme change (solarized, sky, moon) seems to affect only the font and not background colors. Transitions also don't seem to change whether I have slide or none. But It does not prevent me from using the slideshow as I need to, I am only wondering if I am doing things correctly.

This is the notebook metadata:

{
    "celltoolbar": "Slideshow",
    "kernelspec": {
        "display_name": "Python 3 (ipykernel)",
        "language": "python",
        "name": "python3"
    },
    "language_info": {
        "codemirror_mode": {
            "name": "ipython",
            "version": 3
        },
        "file_extension": ".py",
        "mimetype": "text/x-python",
        "name": "python",
        "nbconvert_exporter": "python",
        "pygments_lexer": "ipython3",
        "version": "3.10.9"
    },
    "rise": {
        "scroll": true,
        "theme": "solarized",
        "transition": "slide"
    }
}
``

[mcrovella]

I am also noticing that the background colors of the theme are not being set. For example, the beige theme has a white background color.