[FEAT] Have a way for some subsets to only be shown in some viewers

[eteq]

Jdaviz component

Imviz

What is the problem this feature will solve?

The current behavior when multiple viewers are present and you select a subregion seems to be for the selection to propogate to all the viewers. That's good in some cases, but there are other situation where a subset is really only relevant for one of the viewers but not others.

Describe the desired outcome

It would be good if there was a way to quickly and easily specify "this subset should only be shown on the viewer I'm clicking on". I get that subsets as a data structure are not tied definitively to the viewer, but from a UI perspective, a toggle to turn on or off the show-in-all-viewers behavior on a per-subset basis would be good. Maybe just a toggle in the subset-creation UI?

Additional context

🐱

[kecnry]

toggling the display of the subset per-viewer is currently supported in plot options. If its a common workflow, then maybe we would want to expose it in a more convenient way, but if its not common, I think this should do the trick?

[pllim]

@kecnry , can we do the same thing with markers? Just in case if we ever go with #2238

[kecnry]

Probably, but not directly out-of-the-box.

I think both the astrowidgets and plugin implementation of markers are at the bqplot-level, whereas the plot options plugin acts on glue layer states. But there's nothing stopping us from extending plot options to also expose some options on the bqplot marks objects (or possibly looking into having them as official glue layers while still avoiding putting them in the data-collection, if necessary).