[XeTeX] New version of xetex

[David Carlisle]

> \hbox \bgroup $\beginR

but couldn't you just do

\hbox \bgroup \beginR$

to get the same, but working with older engines?

> I will look at longtable and see if the same kind of thing can be done there.

I don't have it here but can you put \beginR at the start of $$ and
still have a display \halign? if so you could easily make longtable do
the right thing....

$$\beginR\halign{&#\hfil\cr a&b&c\cr}\endR$$

?