Color font TTF composite bug


I am experimenting with a color font in COLR-CPAL format. Trying out if I can make an agrave as a composite from a and grave, the preview in the app looks OK.
When I generate a font and check it out, the agrave shows up wrong. When I open the TTF in a TTF editor, I can see the color layers appended as glyphs. The agrave shows up as 3 composites: agrave.layer0, agrave.layer1 and agrave.layer2. Unfortunately for all three the components are the normal a and grave, rather than the .layer0, layer1 and .layer3 glyphs. If I make a manual change of the composites everything shows up fine, so the references in the tables are OK.


Could you send me the file?

When adding mark attachment I spotted what looks like a side-effect.
In the mark to base lookup the agrave inherits the top anchor of the spacing grave that is used as component, which is OK. But the 3 color layer glyphs also inherit the anchor and are listed in the lookup. It doesn’t do any harm as they aren’t used. But it takes up size. The color layer glyphs of composites are also listed in the GDEF as base, which isn’t needed either.
Finally the color layers of combining marks with anchors are also listed as mark in the GDEF.