[XeTeX] t caron problem (gentium font?)

[Arthur Reutenauer]

	Hello Václav,

  What you see is the combination of two things:

  1. You're using Gentium Basic, which is a fork of the Gentium project
  that adds boldface to the Gentium fonts, but with much less glyphs
  (Gentium proper doesn't have bold faces, only roman and italic).

  These fonts do not contain the lowercase ť at all – although, for some
  reason, they contain the uppercase Ť.

  2. Some package is trying to be smart and compose the character for
  you, but in the absence of the glyph in the font, all it can do is
  compose it from the plain Latin t and the combining caron.  I don't
  know what package does that in your case; if I try to reproduce your
  problem, all I get is a blank box that indicates the absence of the
  glyph, like Michael just said.  I tried with xunicode and the latest
  development version of fontspec, but got the same result.

  I'm afraid the conclusion of all that is that Gentium simply isn't fit
for Czech typography, and you have to use Gentium (which means you'll
have no bold face).

> However, Gentium proof prints clearly _do_ have the correct form of ť
> (http://scripts.sil.org/cms/scripts/render_download.php?site_id=nrsi&format=file&media_id=Gentium_RU_proofs&filename=Gentium_RU_proofs.pdf, page 5: precomposed latin diacritics lowercase).

  These are the proofs for Gentium, not Gentium Basics.

	Arthur