[luatex] Bad skips with display math

[Javier Bezos]

> 👍 It didn’t occur to me to think of the old good bidi features
> of etex and I was just playing with \...dir’s. After some simple
> tests it seems to do the trick.

After some additional tests, setting \predisplaydirection=0
doesn’t seem the solution 🙁.

Any additional suggestions on how to make luatex usable for
serious math typesetting with RTL languages will be welcome.
This includes the possibility of manipulations at the lua
level (for example, I’m wondering if something similar to the
macro \lastlinelength in sec. 7.7.2 can be used to catch and
fix the spacing).

I'm just looking for a solution. After tree weeks of fighting
I’m somewhat desperate.

Javier