CSS Class Names: Add button to choose from block styles

[shaunandrews]

When switching between block styles, the "Additional CSS class(es)" input within the Advanced accordion of the sidebar also updates to reflect the new style.

It might be nice to connect these two UI's a little, and offer a way to choose from the defined block styles from the Advanced section.

[kjellr]

I'm not totally sure this extra feature is necessary, but if we were to add it, I think the mockups would benefit from some sort of header/title/prepended label inside of the dropdown to be clear that the options there are Styles.

[mtias]

This would play well with the ability to register your own user styles once we get there.

[ramonjd]

I've made a first, and very rough, pass at this. The list won't show for blocks with no styles.

I'm not also convinced it's necessary, but one argument for the feature would be that the editing styles class value is already connected to the styles controls.

So if you happen to clear the CSS style names manually, and your mouse is loitering about that place anyhow, then it's easier to restore and preview the alternative style options.

[kjellr]

I'm not also convinced it's necessary, but one argument for the feature would be that the editing styles class value is already connected to the styles controls.

Yeah, that's a good point. Seems like a good reason to give this a try at least.

[ramonjd]

Closing for now until we can revisit the approach.

I've closed the attached PR, which explored a few avenues but ultimately couldn't achieve the desired design 1:1.

We can always reopen if folks think this feature is required and we can use what we've learned.

Thanks to everyone for their help on this one!