[112 new] Extension: Combining Diacritics and GPOS features for positioning

[Denis Moyogo Jacquerye]

Many of the charcters in Unicode Blocks Combining Diacritical Marks (0300) and Combining Diacritical Marks Supplement (1DC0) are used in languages orthographies. Having the characters and OpenType GPOS features to correctly place them would be great.

Examples:
Russian, Cyrillic script: нога́ НОГА́
Lingala, Latin script: mbɔ́tɛ MBƆ́TƐ
Yoruba, Latin script: ẹ̀tọ́ Ẹ̀TỌ́
stacking: ɛ̄́ Ɛ̄́

For GPOS features, they also need to be added to all base characters so it's quite a project.

This blocks bug 670758 Expansion: IPA and Combining Diacritcals to cover more Latin-based African languages.

[Alessandro Ceschini (alessandroceschini-it)]

Yeah, I 100% agree, for instance, in Serbian there are five diacritics that are used in dictionaries and learners' literature.
U+0300 COMBINING GRAVE ACCENT
U+301 COMBINING ACUTE ACCENT
U+030F COMBINING DOUBLE GRAVE ACCENT
U+0311 COMBINING INVERTED BREVE
U+0304 COMBINING MACRON

Unfortunately, Ubuntu displays them, NOT as combining diacritics, but just like another character that follows the modified character, rather than being on top of it.

[Matthew Paul Thomas (mpt)]

A few of these symbols would be most reliably designed together (for example, those that come in pairs), but most of them would not. I think this bug report would be both easier and more interesting for contributors to tackle if it was split up into one bug report per language: for example, "Missing diacritics+positioning for Serbian" and "Missing diacritics+positioning for Yoruba".