Theme JSON schema: Add sticky position to settings, minHeight to styles

[andrewserong]

What?

Update theme.json schema to include position.sticky within the settings schema, and dimensions.minHeight within the styles schema.

Note that while fixed is treated as a valid value in code, it is not yet in use by any core blocks. To avoid folks thinking they can start using it by switching fixed to true, I've left it off this change for now.

Why?

Now that the sticky position support has been added to the Group block, and the feature will be in 6.2, ensure the setting exists within the theme.json schema.

Also, dimensions.minHeight was missing from the style schema, so that's been added now.

How?

• Update the theme.json schema to reflect that position.sticky is a valid setting (boolean) — note that position is not valid as a style within theme.json as it is intended to be set at the individual block level within the editor.
• Add dimensions.minHeight as a valid style.

Testing Instructions

Proofread to make sure the changes look correct, and are added in the right places. I wasn't too sure how else to test it manually?

[aaronrobertshaw]

Thanks for bringing the schema up-to-date with the current state of position support @andrewserong 👍

The decision to omit references to fixed position support makes sense.

LGTM!

[aaronrobertshaw]

Thanks for also adding the missing dimensions to the schema styles and settings.

It looks like this has exposed a problem with the previous dimensions setting definition. It needs the object type as well I think.

[andrewserong]

Thanks for the reviews @aaronrobertshaw! Added the missing line, so 🤞 should be good now.

[aaronrobertshaw]

The latest tweak LGTM. Once the e2es pass, this should be good to go. 🚢

[andrewserong]

I've added the backport label — I'm not sure if it's needed for schema updates? It was flagged in this issue (#49010), though, so to be on the safe side, I've added the label.

[pbiron]

All the references I see to the schema just point at https://raw.githubusercontent.com/WordPress/gutenberg/trunk/schemas/json/theme.json, so I don't think the schema is "distributed" with WP installations, so there's nothing that needs to be done there (since that now contains the new properties).

With regard to merging this into core, ,

I suspect that the .md file will get incorporated into the the relevant handbook page during some automated sync'ing that happens after a WP release, but probably best to check with the release/documentation leads.

[Mamaduka]

I just cherry-picked this PR to the wp/6.2 branch to get it included in the next release: 33001e5