[meta] [upstream] Prioritized CKEditor 5 upstream blockers

This issue centralizes the coordination and prioritization for all issues tagged Needs upstream bugfix or needs upstream feature — i.e. issues that require coordination with the CKEditor 5 team upstream.

@lauriii and @Wim Leers did the prioritization in a Google Spreadsheet (everyone can view & comment!). See methodology below.

Prioritized list

1. #3384400: [upstream] [Table] CKEditor 5 changes <thead> and keeps only a single <tbody>, which impedes screen reader accessibility of HTML tables
2. #3332416: CKEditor 5 toolbar items of multi-value field (typically Paragraphs) overflowing on narrow viewports and overlapping with node form's sidebar on wide viewports

🔝 The top 2 (of the remaining ones — see "fixed" list below) have a significantly higher priority than the bottom 10! ⚠️

3. #3333494: [upstream] CKE5 Code Blocks missing type around wrapper
4. #3335991: [upstream] [GHS] CKEditor 5 does not retain custom HTML tags that are not defined by CKEditor 5 plugins whenever /.*/ is not allowed (e.g. when filter_html is enabled)
5. #3362002: [upstream] [GHS] CKEditor 5 stripping <h2> tags (and more) if inside <div>
6. #3398223: [upstream] [Style] [GHS] empty elements do not work: <br class>, <hr class>, <col class> etc.
7. #3395434: [upstream] [Table] CKEditor 5 editing table with rowspans removes header property
8. #3280124: [PP-1] [upstream] Consider allowing styles for non-HTML5 tags
9. #3259367: [upstream] Allow configuring *which* HTML tags can be aligned
10. #3231168: [upstream] Adding &emsp; in source editor adds &nbsp; to the end of lines

Obsolete

• #3339741: Clicking on an anchor link within a WYSIWYG navigates to anchor → not upstream bug per #3339741-7: Clicking on an anchor link within a WYSIWYG navigates to anchor
• #3342874: Allow inline HTML comments in CKEditor 5→ not upstream bug per #3342874-17: Allow inline HTML comments in CKEditor 5

Fixed

10.1.0

1. ✅ #3339763: [upstream] CKEditor 5 mangles table structure → fixed in CKEditor 37, shipped in Drupal 10.1: #3355358: Update CKEditor 5 to 37.1.0

10.1.1

1. ✅ #3326261: [Style] Add tests for inability to apply styles to <div>, <ul>, <ol>, <table> etc. in CKEditor 5 — and <a> allows applying it to all elements → fixed in CKEditor 38.1.0, shipped in Drupal 10.1.1: #3370989: Update CKEditor 5 to 38.1.0
2. ✅ #3349893: [upstream] [GHS] CKEditor 5 removes <a>s that wrap HTML elements not natively supported by CKEditor 5 → fixed in CKEditor 38.1.0, shipped in Drupal 10.1.1: #3370989: Update CKEditor 5 to 38.1.0

10.1.3

1. ✅ #3337298: [upstream] [GHS] CKEditor 5 removes empty inline elements → fixed in CKEditor 39.0.0, shipped in Drupal 10.1.3: #3377562: Update CKEditor 5 to 39.0.0

10.2.0

1. ✅ #3321296: [upstream] CKEditor 5 breaks website CLS (no image width and height attributes) → fixed in CKEditor 40.0.0, shipped in Drupal 10.2.0: #3393557: [upstream] Update CKEditor 5 to 40.0.0
2. ✅ #3254346: [upstream] CKEditor 5 PasteFromOffice plugin should not allow MS Office/Apple Pages/Google Docs-specific classes and styles even when HTML is unrestricted → fixed in CKEditor 40.1.0, shipped in Drupal 10.2.0: #3400791: Update CKEditor 5 to 40.1.0

10.6.0 / 11.3.0

1. ✅ #3321254: [upstream] Remove Format button does not remove `style` attributes from block-level elements → fixed in CKEditor v46.0.0, shipped in Drupal 10.6.0 / 11.3.0: #3538768: Update CKEditor 5 to 47.0.0

11.4.0

1. ✅ #3331158: Support full-screen editing in CKEditor → fixed in Drupal 11.4.0

Methodology

For each issue, we specified:

• Reach (% of sites affected
• Impact (1–10, with: data loss = 10, semantics loss = 9, inconvenience = 1)
• ⇒ multiply these to get a "Drupal priority" → color coded based on this: red = very high impact, orange = high, yellow = medium, gray = low
• Effort to fix on Drupal side to determine if we should work around the problem on the Drupal side instead (0–1 — impossible/unmaintainable = 1, feasible = 0.5, easy = 0.25)
• ⇒ multiply the effort with the Drupal priority to get a "CKEditor 5 priority" → sorted based on this

This gives us an ordered list of issues, to clearly indicate which CKEditor 5 issues are most important for the Drupal ecosystem/community to get fixed.