This works, but the popover is a bit odd. Is this something that can be expanded? I’m not sure what the limitation of the popover is in regards to displaying characters.
The small caps in those Adobe fonts are at codepoints in the Private Use Area, U+F761–F77A. These have no glyphs in most fonts, such as Source Sans in the popover. So what you’re seeing as a fallback is actually Bravura Text, which happens to have vertically shifted versions of the Circle X whole notehead glyph at those codepoints. They draw on top of each other because like all the noteheads they have zero advance-width.
The Circle X whole notehead in regular Bravura is U+E0B1. Bravura Text has several copies of most of the glyphs in Bravura because it accommodates vertical shifting by half-spaces using the “combining staff positions” codepoints (U+EB90–EB9F), through the magic of OpenType. See Metrics and glyph registration for text-based applications in the SMuFL spec.
Thanks Mark, makes sense.
It would be interesting to know from Daniel if all Source Sans glyphs are able to be represented in the popover… if so, I might consider modifying the font to map these small-caps letters to more familiar glyphs (I’m only ever using O, R, and D in lyrics!).
I’d say go for it! There’s no reason codepoints you add should not display, as long as Dorico has no problem using your modified font.