[XeTeX] xetex crash: interaction between interchar and linebreaklocale mechanisms

[Javier Bezos]

> According to documentation it seems to me that ucharclasses work only
> with XeLaTeX. 

But with babel and lualatex you can switch the font depending
on the script, even with RTL ones, which, if things haven’t
changed, isn’t possible with ucharclasses. See the examples
in p. 44 of the babel manual.

Javier