This is a follow-up issue to #5754, in which we widgetized the Matplotlib nbagg backend for Jupyter notebooks.

I'm using this pretty extensively, so I'm happy to report issues I find here. I'd also like to personally fix them, but I will need some guidance on how to do that. So far, I've found 3 things that we should fix:

1. The Matplotlib widget does not respect layout widgets as much as it should.

If I place widgets in layouts, they are autoscaled to not run over the sides of the notebook (for instance). Matplotlib always defaults to a particular size, which means it often runs over. See the below screenshot

2. The titlebars seem unnecessary much of the time.

I suspect most users in notebooks don't really care about having a titlebar in the figure. We should make it easy to turn this off. Maybe this should be the default? Is it already possible to do so?

3. Getting the widget that needs to be added to Jupyter layouts is mysterious.

To actually put the widget in a layout, one needs to get fig.canvas.manager.canvas and add that to a layout. That's not really the API we want, is it? Is there a way we can make this easier?

Pinging who I think are the relevant people: @blink1073 @tacaswell @mdboom @SylvainCorlay