Unable to change the lightbox settings of the Image block within Global Styles when KSES is active

[ramonopoly]

This ticket corresponds to the bug report in ​https://github.com/WordPress/gutenberg/issues/73157

When KSES filters are active (via add_action( 'init', 'kses_init_filters' )), valid non-preset settings in Global Styles are being incorrectly filtered out. Specifically:

• lightbox.enabled and lightbox.allowEditing for Image blocks

The issue occurs because remove_insecure_settings() only preserved:

1. Presets (from PRESETS_METADATA)
2. Indirect CSS properties (from INDIRECT_PROPERTIES_METADATA)

Step-by-step reproduction instructions

1. Enable the KSES filters with add_action( 'init', 'kses_init_filters' );
2. Go to Appearance > Editor
3. Open the Styles sidebar
4. Select "Blocks"
5. Select "Image"
6. Change the "Enlarge on click" options
7. Save the changes

⚠️ Note how the changes are reverted

A PR to sync ​https://github.com/WordPress/gutenberg/pull/73452

## Problem

When KSES filters are active (via add_action( 'init', 'kses_init_filters' )), valid non-preset settings in Global Styles are being incorrectly filtered out. Specifically:

• lightbox.enabled and lightbox.allowEditing for Image blocks

The issue occurs because remove_insecure_settings() only preserved:

1. Presets (from PRESETS_METADATA)
2. Indirect CSS properties (from INDIRECT_PROPERTIES_METADATA)

All other valid settings were being stripped, even though they're defined in VALID_SETTINGS and are safe scalar values or arrays.

Related Issue: ​https://github.com/WordPress/gutenberg/issues/73157

## Solution

Added a new preserve_valid_settings() method and SAFE_SETTINGS const that work to preserves valid settings.

## Testing Instructions

### Manual Testing

1. Enable KSES filters:

   add_action( 'init', 'kses_init_filters' );
   

Add this to your theme's functions.php or a plugin.

2. Test Image Block Lightbox Settings:
   • Go to Appearance > Editor > Styles
   • Navigate to Blocks > Image
   • Open the Settings panel
   • Toggle the "Enlarge on click" (lightbox) setting
   • Save the changes
   • Expected: The setting should persist after saving and page reload
   • Before fix: The setting would revert after saving

3. Test Other Valid Settings:
   • Try changing other valid settings in Global Styles (e.g., layout settings, spacing settings)
   • Save and verify they persist
   • Expected: All valid settings should be preserved

Trac ticket: https://core.trac.wordpress.org/ticket/64280

[ellatrix]

@ramonopoly Was this introduced in trunk (6.9)?

[ramonopoly]

Was this introduced in trunk (6.9)

Are you asking which milestone this should be?

I've updated it to 7.0. The bug has been around for eons. See:

​https://github.com/WordPress/gutenberg/pull/73452#issuecomment-3562566719

[ellatrix]

Oh, I see it's filed under trunk which I thought means that it's introduced in the current unreleased version.

[ramonopoly]

Oh, I see it's filed under trunk which I thought means that it's introduced in the current unreleased version.

Oh, that is a very good point.

I think the bug was introduced in 6.4!

​https://github.com/WordPress/gutenberg/pull/54509

So the "version" is the affected version. ​https://make.wordpress.org/core/handbook/contribute/trac/

I get it. I can update.

Thanks for checking.

[ellatrix]

No worries. There's a lot of tickets filed wrongly under trunk I think, I just picked a random one to figure out why :)