scattergl fill tozero fails in some weird ways

[etpinard]

splitting the first item in #2450 into issue of its own (which should be easier to track)

codepen: https://codepen.io/alexcjohnson/pen/YemVOd

[emmanuelle]

I think this problem is the same as an issue recently opened by a Python user plotly/plotly.py#2018.

[gvwilson]

Hi - we are currently trying to tidy up Plotly's public repositories to help us focus our efforts on things that will help users most. Since this issue has been sitting for several years, I'm going to close it. If it's still a concern, we'd be grateful if you could open a new issue (with a short reproducible example if appropriate) so that we can add it to our backlog. Thanks for your help - @gvwilson

[rweigel]

This issue is still a concern. I don't think it makes sense to open a new issue given the links, example, and discussion here are informative.

[gvwilson]

Thanks @rweigel - I'll reopen this one, assign it to myself, and try to get it into our backlog.