Jupyter cells need a "i'm calculating" indicator

[moorepants]

When a user executes a cell it may take some time to complete or even never complete. We need a way for them to know that the calculation is occuring. And thus a "stop" button is likely needed too.

[moorepants]

sphinx-thebe implements a very clear indicator:

[moorepants]

Can we copy this indicator from sphinx-thebe (or something similar) and implement in our ckeditor plugin? That would solve this.

[sandertyu]

I think this is solved by the ckeditor binder plugin status field changes?

[moorepants]

One issue is giving more feedback on the initial connection to binder, which I think we now have. But the second issue is getting feedback when you run an individual cell. We should clarify more these two needs. I think for the second one we may need improvements to thebe.

[moorepants]

When running a cell in a Jupyterlab notebook there is this indicator:

That circle turns grey when the cell is calculating. There is likely a way to get thebe to tap into that signal.

[TimStewartJ]

Is this solved by jupyter-book/thebe#424? It sounds like this is what we were looking for.

[moorepants]

Yes, we just need to make a new thebe release.

[moorepants]

A spinner is now default in thebe 0.8.0. See jupyter-book/thebe#424, closing.