Support for hover/legend with InteractiveImage?

[jordansamuels]

When putting several series in the same interactive image, it's helpful to have a mouse-over/hover to identify the series and point; and/or a legend (ideally like dygraph legends, which are sort of liked docked hovers in that they always show the points and identify the series). I see how to get hovers with non-interactive images from the notebooks/hover_layer.ipynb example; but it wasn't clear to me how to get this working with InteractiveImage.

[jbednar]

Right. Unfortunately, making that work well is one of our older open issues (#126). It's assigned to me, and I'd really like to get it running too, but I haven't yet made progress on it. I've recently worked out what I think is a good plan, though, and I hope to implement it soon! It's listed at the end of that issue now.

Providing hover information has similar issues to legends, in that metadata about the plot needs to be provided in a principled way to InteractiveImage, but I'll try to make progress on legends first.

[tommycarstensen]

I'm very happy to be a tester on this.

[jbednar]

I'll go ahead and close this, as it's covered by #126.