[XeTeX] misplaced combining diacritical marks 2

[Alexander Schultheiß]

Hello Peter,

> Something odd is going on here, but I don't think it has to do with anchor
> marks. Junicode actually has a precomposed character m + macron + acute +
> dot below. It's not a Unicode character, but rather is unencoded. (I can't
> remember why it's there: maybe a user asked for it at some point.) It should
> be getting substituted (via ccmp, the earliest lookup performed) whenever
> the renderer sees the sequence m + U0323 + U0304 + U0301 or m + U0304 +
> U0301 + U0323. I think that ICU/XeTeX is probably doing the right thing at
> this point. But Junicode's precomposed character is made of references
> instead of outlines, and sometimes ICU/XeTeX (not sure who's doing the
> rendering at this point) gets confused about glyphs composed of references.

Ok, haven't looked into glyph composition yet. I've found the entries
that compose the mdotmacronacute. It looks like the glyph I composed
by hand and attached to one of my previous posts (test4.pdf line 3.3)
but not quite like the mdotmacronacute in lines 2.2 and 2.4-6. Is this
maybe a rendering problem? Is there an order in which all the
informations in the GSUB and GPOS tables are evaluated by xelatex?

> Alexander, if you don't mind my sending you a big file off-list, I'd like to
> see if a change in the Junicode font will fix the problem.

I certainly don't mind, though I'm quite a beginner when it comes to
fonts and so far don't understand a great deal about many internals.
To me much of this is simply voodoo.