Context menu 2: add support for multiple selection

[abey79]

What

• Follow up to Context Menu 1: Basic scaffolding and simple actions #5163
• Part of Add contextual menu to blueprint tree for common actions #4823

This PR adds support for multiple selection with context menus in blueprint view.

The selection logic is as follows:

• If the (right-)clicked item is part of the selection, the context menu actions apply to the entire selection.
• Otherwise, the selection is set to the clicked item, and the context menu actions apply to that item only.

This PR doesn't introduce any new action, but adjust the existing ones to handle multi-selection:

• If only space views and/or containers are selected, the visibility toggle and Remove actions are offered. The visible toggle will offer to show if one or more items are currently hidden, and hide if all are currently visible. If the root container is part of the multi-selection, its is ignored by those actions.
• The "Add SV/Container" actions are offered only if exactly one container item is selected.

TODO in future PR:

• additional actions
• entity level manipulations
• use ListItem instead of label/WidgetText
• better folder structure
• release checklist update

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using newly built examples: app.rerun.io
  • Using examples from latest main build: app.rerun.io
  • Using full set of examples from nightly build: app.rerun.io
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG
• If applicable, add a new check to the release checklist!

• PR Build Summary
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• Recent benchmark results
• Wasm size tracking

[teh-cmc]

Is there something we can do to prevent the hover pop up in that case?

[teh-cmc]

Something super weird happens sometimes that i cannot quite explain in words:

24-02-16_09.14.37.patched.mp4

[teh-cmc]

If you do an heterogeneous selection and then right-click, the context menu pops up in the form of an empty bubble for a frame, it's a bit jarring:

24-02-16_09.30.38.patched.mp4

[teh-cmc]

I had no idea all of these things existed 😄 pretty exciting what one can do in the blueprint panel these days 👀

See my other comments for some usage bugs I've found.
I don't think any of them are blocking.

The only one I'm worried is the only where the selection seems to be changing on its own somehow? That might hide a real nasty thing.

I do think the whole context menu thing really really needs a dedicated check in the checklist though (emphasis on dedicated: keep checks as atomic as possible!).

[abey79]

Is there something we can do to prevent the hover pop up in that case?

On my list of things to fix in follow-up PRs. I guess we can remove these one entirely and they serve no purpose. The ones that actually are useful is entities, so I will need to address that properly.

@emilk any input on how to deal with hover tooltip vs. context menu conflict?

[abey79]

The only one I'm worried is the only where the selection seems to be changing on its own somehow? That might hide a real nasty thing.

Yeah that's ugly. Looking into it.

I do think the whole context menu thing really really needs a dedicated check in the checklist though (emphasis on dedicated: keep checks as atomic as possible!).

I originally intended to add this in some later wrap-up PR but I guess I'll introduce it already now. It'll be easier to keep track of the various edge cases as I pour more stuff into those context menu.

[abey79]

If you do an heterogeneous selection and then right-click, the context menu pops up in the form of an empty bubble for a frame, it's a bit jarring:

For this one, I opted to show an explicitly empty context menu:

Slightly less surprising that showing nothing, which would have the additional technical draw back to require computing the list of possible actions for every list item drawn, _every_frame. Currently, this happens only once, and only when a context menu is actually displayed.

[abey79]

The only one I'm worried is the only where the selection seems to be changing on its own somehow? That might hide a real nasty thing.

Yeah that's ugly. Looking into it.

Fixed. Thanks @emilk for the help.