Hi @terryphi,

I agree that this would be nice. Here's a plotly.js issue discussing the request: plotly/plotly.js#689. As mentioned there, it's possible to add text annotations in paper coordinates to act as a legend title (https://plot.ly/python/text-and-annotations/#adding-annotations-with-xref-and-yref-as-paper).

But because plotly.js has a bit of default placement logic for legends, this won't be something that we could reliably automate from Python. So I think this would need to handled in plotly.js. @nicolaskruchten do you agree?

This was implemented in 4.5 :)