Diacritics that should be below characters are not below the base character's descender

[J-J-Chiarella]

For IPA diacritics that go below the baseline like the non-syllabic marker (U+032F Combining inverted breve below) as in u̯), the diacritic does not work correctly with base characters that have descenders, characters like y. Writing y̯ will draw the breve below the baseline but not below the entirety of the base character (y) glyph. The diacritic is slightly to the right of the descender, but this is not enough to avoid bleeding over. When printing in smaller fonts (or even in 12 pt when viewed from a normal reading distance on a screen), the diacritic will touch the descender of the base character glyph. This also applies to the combining marker (U+035C Combining double breve below) as in p͜f.

For U+032F, the horizontal offset is okay, but it should not be extended further and Doulos should accept going below the descender. The inter-line spacing is generally sufficient and other IPA symbols like U+035C (Combining double breve below) already go below the lowest point of the descenders in the Doulos font.

The diacritics below need to all move slightly further down or else they need to intelligently move down in the presence of glyphs with descenders.

If my desired changes would mess up the inter-line spacing or cause conflicts with multiple stacked diacritics in Vietnamese running text, then please say so. That is a bigger priority for U+032F. Forr U+032F, however, this diacritic is only ever used in phonetic transcriptions, not in running texts of Vietnamese and, therefore, U+032F probably should be clear to move a few tiny bits lower than its current placement.

[jvgaultney]

That placement of combining diacritics - to the side rather than fully below the descender - is intentional, and seems to be preferred by our users. I do understand your concern about the display at small sizes, but we're not likely to change it in the future. The combining double characters are treated differently, as they need to avoid characters on both sides.