Hi,

In MkIV, the syntax for using hz seems to have changed from
\setupfonthandling to \setupfontexpansion (similarly for protrusion).  What
is the equivalent of the following?  Is this feature supported in MkIV and
LuaTeX?  I tried changing/adding entries to
fonts.expansions.vectors.quality (and .default) to no apparent avail.


\startfonthandling [hz]
  \defineadjustfactor A .5
  \defineadjustfactor B .7
  \defineadjustfactor C .7
  ...
\stopfonthandling


In any case, I'm happy that hz works for Arabic/Farsi despite some warnings
suggesting the contrary (
https://mailman.ntg.nl/pipermail/ntg-context/2008/029765.html).  It does
make certain Farsi texts look better, however, support for tatweel/kashida
would be ideal.  In fact, I was trying to see if I could somehow get it to
work, building on top of hz.  Hans, do you have any suggestions for this?
Would this be feasible and/or worth trying?

I once converted Vafa Khalighi's XeTeX-based code to Lua but ran into
several setbacks.  (The idea is to insert a sequence of
(ZWJ,\nobreak,stretchable leader,\nobreak,ZWJ) between certain character
pairs that join one another.)  Here are some of the issues I faced:
1) This could not be turned off and on within a paragraph because I was
hooking into processors.before action.
2) The mechanism for some (all?) center alignments (including default
figure captions) interferes with what I was hacking (or, to be more
precise, it's the other way around) and causes unnecessary use of tatweel
in those settings.
3) Later I noticed that the added sequence did not inherit many properties
(like font style or color).
4) The optimum values for the stretches I put in depend on the context,
particularly because some environments manipulate \spaceskip for other
reasons.

Sorry for the mumbling.  I can explain more if anyone is interested in
helping to improve this functionality.  Attached is what I have now.

Thanks,
MHB