Post Title block - add spacing.margin support

[colorful-tones]

Description

Addresses #35522

How has this been tested?

Tested and verified changes locally with TwentyTwentyTwo theme enabled.

Screenshots

Types of changes

General spacing margin support was rolled out in Spacing Support: Add margin block support with configurable sides #30608. Here we're adding the margin spacing support to the Post Title block.

Props to @aaronrobertshaw and @Mamaduka for guidance on getting this PR in motion

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• n/a My code follows the accessibility standards.
• n/a I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• n/a I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).

[kjellr]

Thanks @colorful-tones! This works as expected, and it gets the margin working on the front-end.

That said, from my tests around margin support it appears:

• Margin entered in block markup for the post title works in the editor at all times: Even if support has not been declared here or in the theme.
• Margin entered in block markup only works in the front-end if its specifically declared in block.json (as you've done in this PR).
• The UI only shows up if the theme has opted in via theme.json.

This seems wrong? Whatever the behavior, there shouldn't be a mismatch between the front-end and the editor. I think this PR seems fine, but that bug still exists either way.

I also think it's going to be tedious to enable this on a per-block basis. Margin feels like the sort of control that should be enabled globally, even if the UI isn't shown per-block. So I think we should hold off and discuss that for a moment in #28356 before we merge.

[colorful-tones]

Whatever the behavior, there shouldn't be a mismatch between the front-end and the editor.

Totally agree. 💯

I also think it's going to be tedious to enable this on a per-block basis. Margin feels like the sort of control that should be enabled globally, even if the UI isn't shown per-block.

Again, agree.

I really like the idea of having preset options for margin/padding, see: Add a selection of preset spacing values to supplement/replace custom padding/margin options #35306.

Similar to Font Size: Small, Medium, Large, Extra-Large. I feel like these values would be a good first step for theme authors and users. Then, a Phase II and further down the line we add ability for users to place custom Margin/Padding (per position: top, left, right, bottom) and incorporate that in to theme.json/FSE.

I will monitor #28356 for further discussion. Thanks @kjellr

[kjellr]

I opened a more expansive version of this PR so we can (hopefully) get this working more consistently across all heading blocks: #35772

I also opened WordPress/twentytwentytwo#135 to add custom margin support into Twenty Twenty-Two.

[carolinan]

I honestly do not understand why we want it limited to top and bottom?

[kjellr]

I honestly do not understand why we want it limited to top and bottom?

I think the main argument is that left/right margin will frequently break in classic themes. See the notes in #33835 (comment).

[kjellr]

@colorful-tones i think we’re all set on this one now due to #35772 being merged. Thanks for getting the ball rolling!

[ndiego]

Just stumbled on this PR. @colorful-tones can this be closed since #35772 is merged?

[colorful-tones]

@ndiego yes, I just closed. Thanks for reminder! 👍