Focus handling of buttons in "Show more items" tray is broken

[lauriii]

📝 Provide detailed reproduction steps (if any)

1. Enable enough buttons in the toolbar to get the "Show more items" tray to show up
2. Click a button inside the "Show more items" tray 
3. Focus is returned to the "Show more items" tray toggle button, not where it was actually intended to return.

✔️ Expected result

For example, if a list is added from a button that is in the "Show more items" tray, focus should return to list in the editor.

❌ Actual result

Focus is returned to the "Show more items" tray toggle button

📃 Other details

Tested on HEAD, f811d49

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[mlewand]

Thanks, we're aware of this issue it's reported as #12178.

Meanwhile we have a PR proposal to address this issue so you can see if the problem is gone there: #12319