Thanks to Thomas and Denis,

That's it: use GFS Didot for the French text and Theano Didot for the Greek. In my working text I have this preamble (and other things):

\setuplanguage[fr][patterns={fr,agr}]
\mainlanguage[fr]
\setcharacterspacing[frenchpunctuation]]
\setuplayout [backspace=40mm]
\setuppagenumbering[alternative=doublesided, location={header, inmargin}]
\setupmargindata[inmargin][location=inner, style={setupinterlinespace[line=2.8ex]}]
\setupmarginframed[inmargin][align=right]
\setupbodyfontenvironment[default][em=italic]
\definefallbackfamily[mainface][rm][Theano Didot][preset=range:greek,force=yes]
\definefontfamily[mainface][rm][GFS Didot]
\setupbodyfont[mainface, 11pt]

I'm currently working on MS Windows 11 for the moment (as a test beside Linux). I didn't try to compile this text under Linux, but I don't think there is an issue with the OS.

As far as GFS Didot is concerned, I have installed the most recent version. But what amazes me the most is that by only keeping a font like EBGaramond without writing :
\definefallbackfamily
 [mainface]
[rm]
[Theano Didot]
[preset=range:greek,force=yes]
So, using EBGaramond only, I have the French text (with italics), as well as the Greek text...

Try this :

\setuplanguage

\mainlanguage[fr,agr]

[mainface]

[rm]

[EBGaramond]

\setupbodyfont[mainface, 12pt]

\setupbodyfontenvironment[default][em=italic]

\starttext

Socrate est descendu au Pirée et affirme sa satisfaction du culte rendu à cette nouvelle déesse par les Thraces; néanmoins, {\em il ne nous dit rien des prières} qu'il a lui-même rendues à la déesse avec les autres participants, dont il fait pourtant état. Sur le chemin du retour, il est arrêté par Polémarque qui leur apprend qu'une retraite aux flambeaux à cheval est prévue par les Thraces, ainsi qu'une fête de nuit \quote{qui vaut la peine d'être vue} (ἣν ἄξιον θεάσασθαι; {\em èn axion théasasthai} - 328a).

\blank

Κάθε άνθρωπος δικαιούται να επικαλείται όλα τα δικαιώματα και όλες τις ελευθερίες που προκηρύσσει η παρούσα Διακήρυξη, χωρίς καμία απολύτως διάκριση, ειδικότερα ως προς τη φυλή, το χρώμα, το φύλο, τη γλώσσα, τις θρησκείες, τις πολιτικές ή οποιεσδήποτε άλλες πεποιθήσεις, την εθνική ή κοινωνική καταγωγή, την περιουσία, τη γέννηση ή οποιαδήποτε άλλη κατάσταση.

Δεν θα μπορεί ακόμα να γίνεται καμία διάκριση εξαιτίας του πολιτικού, νομικού ή διεθνούς καθεστώτος της χώρας από την οποία προέρχεται κανείς, είτε πρόκειται για χώρα ή εδαφική περιοχή ανεξάρτητη, υπό κηδεμονία ή υπεξουσία, ή που βρίσκεται υπό οποιονδήποτε άλλον περιορισμό κυριαρχίας.

\stoptext

I've found a solution, with Segoeui (Windows font) as the main font and Theano Didot for the Greek text.
But I don't understand why setting the fonts to GFS Didot and Theano Didot prevents italics from being displayed ...

Best//JP

I just tried your example with the latest version of GFSDidot (the older version I had on my system did not show some diacritics; this problem disappeared when I installed the latest), and the italics are there, I don’t see any problem in the pdf. If you want the Greek displayed in Theano, you will have to add “force=yes” to your definition of the fallback family:

\definefallbackfamily
    [mainface]
    [rm]
    [Theano Didot]
    [preset=range:greek,force=yes]

Your text cannot have two main languages, so 

\mainlanguage[fr]

If you want hyphenation for your Greek passages, you can add

\setuplanguage [fr] [patterns={fr,agr}]

The line where you have polytonic Greek does not use precomposed characters, but combinations of greek characters and diacritics; this will probably not work in recent context versions that expect actual unicode input. 

I hope I have really understood what you want: GFSDIdot for the French text and Theano for Greek?

HTH

Thomas

On 26. Feb 2024, at 13:32, Jean-Pierre Delange <adeimantos@free.fr> wrote:

Dear list,

When handling the preamble to a document in which I would like to treat the text in French, with sometimes italics text and phrases in ancient Greek, I encounter the following difficulty:
if I use TeX Gyre Pagella as the main font, everything works fine, except for the Ancient Greek text, which I don't like the look of. But the Greek text is displayed, as are the French italics. On the other hand, if I use GFS Didot as the main font and Theano Didot for the Greek, the italics disappear and the Greek text looks better. The CTX version I use is: mtx-context | current version: 2024.01.24 22:39.

Herewith are two MWE attachments (*.tex + *.pdf) with different fonts. What am I missing ? Thanks for your answers.

JP

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / https://mailman.ntg.nl/mailman3/lists/ntg-context.ntg.nl
webpage  : https://www.pragma-ade.nl / https://context.aanhet.net (mirror)
archive  : https://github.com/contextgarden/context
wiki     : https://wiki.contextgarden.net
___________________________________________________________________________________