Add mention of being able to enable appearance tools via theme_support to handbook page

[annezazu]

Issue Description

Currently, the converting to a classic theme is missing a very recent PR that likely can be added to this section to help folks adopt parts of FSE. This is available as of Gutenberg 14.0 so not sure whether to wait for 6.1 to be released or to mention now :)

URL of the Page with the Issue

https://developer.wordpress.org/themes/block-themes/converting-a-classic-theme-to-a-block-theme/

Section of Page with the issue

Add under this section perhaps as a new heading: https://developer.wordpress.org/themes/block-themes/converting-a-classic-theme-to-a-block-theme/#enabling-block-features

Why is this a problem?

It's missing another neat way to adopt aspects of FSE without switching to a block theme or even using theme.json. To quote the PR:

Appearance tools are options in the block editor and don't require the use of the FSE to take advantage of. However there's no way to enable those tools for themes that don't use theme.json.

There now is a way and it would be great to document this!

Suggested Fix

Include reference to the ability to enable appearance tools via a new theme support based on this work: WordPress/gutenberg#43337

Here's suggested text based on the other sections (trying to keep it brief):

Enable Appearance Tools in classic themes

To enable appearance tools, like border or margin, you can use the following theme support:
add_theme_support( 'appearance-tools' );
If you do eventually add a theme.json file, it's best to switch to managing these tools from this file rather than using this theme support.

[colorful-tones]

I would be happy to take this on, but I'm unsure about the timeline. I could get the update ready and queue it up for publication to be for the 6.1 milestone.

Even if it is a matter of setting a personal reminder and circling back in a few weeks, I can also do that.

For now, I'll self-assign, but if anybody has a direction of when to publish, then feel free to drop your feedback.

Thanks for getting this on the radar @annezazu

[annezazu]

I'm not quite sure either! I think it's safe to wait for 6.1 so perhaps plan for that and schedule the update if that's an option.

[colorful-tones]

@annezazu it seems that the add_theme_support( 'appearance-tools' ) did not actually make it into the 6.1 release. Therefore, I'm not sure it is worth highlighting yet. 🤔

See latest here: WordPress/gutenberg#43337 (comment)

[annezazu]

I just saw that too and am going to try to follow up as best as I can but, yes. For now, we should pause this.

[annezazu]

Punted for sure to 6.2. Let's revisit then :)

[colorful-tones]

I’ve removed the 6.1 label. I’m not sure if tracking issue is still relevant, and I’ll leave it alone.

[carolinan]

The appearance tools theme support is available in Gutenberg, but it does not work.
It was briefly included in 6.2 alpha for testing, but was removed because of bugs with the block gap feature.

A decision needs to be made wether or not the block gap should be supported in classic themes or not.
After that the work to solve the bugs can continue.
For now, this should not be included in the handbook.

[github-actions]

Heads up @kafleg @carolinan @TeBenachi - the "themes" label was applied to this issue.

[carolinan]

6.3 includes two new theme supports:
add_theme_support( 'link-color' );
add_theme_support( 'border' );