Glyphs for characters in other blocks incorrectly falling back to system font

[r12a]

This issue is applicable to Adlam and N'Ko.

When text contains a punctuation mark such as an Arabic question mark, the glyph displayed should be that contained in the Adlam or N'Ko font, if it contains one.

The Gap:

At least one browser on desktop and mobile render the Arabic question mark (and perhaps other punctuation) using a fallback font despite the font containing the appropriate glyph.

Example in N'Ko:

This was tested with the Noto Sans NKo font. In Gecko and Blink the question mark falls back to a different font.

It may be related to a script itemization issue where Adlam or N'Ko is not properly recognized. A request was made to the Unicode Consortium to fix the Script Extensions table.

Other characters from the Arabic and Devanagari script blocks exhibit the same behaviour. For example, a danda used in Limbu, or a tatweel used in Syriac.

More:

• GitHub issue

Tests & results:

• Interactive test, If an N'Ko font contains an Arabic question mark, the glyph rendered should be from that font, and not fall back to an another font.
  

Action taken:

Gecko

Outcomes

The Unicode Consortium has fixed the script extensions table.

Gecko is implementing a fix.

Priority:

A question mark is visible, just not in the correct font. So marking as advanced.

[r12a]

The first comment in this issue contains text that will automatically appear in one or more gap-analysis documents as a subsection with the same title as this issue. Any edits made to that comment will be immediately available in the document. Proposals for changes or discussion of the content can be made in comments below this point.

Relevant gap analysis documents include:
Adlam • N'Ko

[xfq]

The Unicode properties & algorithms group proposed an update to Script_Extensions to include Adlam and N'ko to the appropriate Arabic punctuation marks, and it will be discussed in UTC.

See PRI428g in https://www.unicode.org/L2/L2021/21069-utc167-properties-recs.pdf