Buttons Block: Clicking inserter icon to add a button should use styling of an existing button in the list

[andrewserong]

What problem does this address?

When you hit "enter" from within a Button block, the added button block uses the same styling as the existing button block, which makes it nice and easy to edit a list of similarly styled buttons. However, the inserter button displayed at the end of the Buttons block currently doesn't respect the styling of the existing buttons.

What is your proposed solution?

When you click the + icon at the end of a list of Button blocks to insert an additional Button, let's see about grabbing the styling / attributes of the last Button block in the list and applying that to the inserted block, consistent with the Enter key behaviour.

Here is a screengrab of the current behaviour when we hit "enter" to add a Button block, and when we click the inserter at the bottom of the Buttons block:

Kapture.2022-01-12.at.15.53.43.mp4