[XeTeX] Combining grapheme joiner

[Arthur Reutenauer]

> "In the case of several consecutive combining
> diacritics, an intervening CGJ indicates that they
> should not be stacked but placed horizontally"

  That's what the Wikipedia page says, not Unicode.  Specifically, it
says in the introduction to the section about CGJ that it is “used to
affect the collation of adjacent characters for the purposes of
language-sensitive collation and searching.  It is also used to
distinguish sequences that would otherwise be canonically equivalent”
(The Unicode Standard 5.0, p. 540).  It's much less precise than the
sentence you quote, which might be a bit stretched (note the “citation
needed” tag).  In other words, this kind of behaviour is totally
dependent on the font.  The only case where you can expect CGJ to have,
by default, a visible effect on diacritics is the Hebrew example quoted
on the Wikipedia page (taken directly from the same section of the
Unicode standard).

  The appropriate solution would be to edit the font, or, failing that,
to use a TeX macro.

> I may have posted about this before -- it bugs me
> since I occasionally need especially an e with a
> dot and acute accent placed beside eachother
> rather than stacked (the stacked version being
> hardly legible, apart from being wrong.

  As far as I know, this is the expected behaviour in Lithuanian, where
these two diacritics can appear in conjunction, specifically over the
letter e.  I find it ugly, but that's another question.

	Arthur