Reusable block selection issues

[ellatrix]

Describe the bug

I'm not sure if any of these issues have been reported before.

• It's currently possible to have a block inside a reusable block selected while another outside of it is selected. This seems really confusing to me.
• The rich text toolbar buttons are duplicated, probably because they're all going to the first slot. (The slot name is global.)

• Pressing Tab from a block inside a reusable block focusses the next block outside of the reusable block instead of the inspector. This seems to be caused by having WritingFlow inside reusable blocks. I'm not sure why this is needed.
• Selection is not cleared after Cmd+A and then selecting a block inside a reusable block.

[0aveRyan]

These are separate from the focus issues in #19373, but likely both need to be accommodated in a resolution.

[chrisvanpatten]

I can confirm this in WordPress 5.3 and the latest version of the Gutenberg plugin. Also just to confirm it's not necessarily specific to reusable blocks, but I think specific to nested BlockList components.

(I'm working on a proof of concept component which allows you to store a set of blocks to post meta or another store, which is how I discovered this.)

There's also some funky behavior where the inner block borders can actually fully disappear, but I haven't been able to determine if it's specifically related to this issue or not.

It's similar but here's a screenshot of what I've seen:

[chrisvanpatten]

This continues to be an issue in recent plugin versions. It seems like the nested provider is maintaining its own state around block selection, which means that events in the upper container don't impact the lower container (and vice versa).

As far as I can tell, this issue was observed on the PR which implemented the nested editor (#14367) but hasn't really been addressed since.

[jasmussen]

Can confirm, still a bug. GIF:

Steps to reproduce:

• Create a reusable block of some paragraphs.
• Save, edit.
• Select a paragraph inside.
• Select a paragraph outside.

Might need to repeat steps 3 and 4 a couple of times.

[noisysocks]

My guess is that it's because the selection state is contained in a different registry. Fixing this will likely also fix #18560.

[ZebulanStanphill]

It's worth noting that the misplaced controls still act upon their original block; the controls simply appear in the wrong spot.