[XeTeX] bidi vs luabidi and polyglossia with Hebrew

[Karljurgen Feuerherm]

On July 5, I posted a query due to a problem I was having in creating
media9 buttons in RTL mode. The error I was getting when placing a media
button command in an RTL environment was "xdvipdfmx:fatal: A pending form
XObject at the end of page.²

A. Grahn offered a solution
(http://tex.stackexchange.com/questions/188434/media-button-in-rtl; see
the MWE there) which, however, depended upon using the luaTeX engine in
place of XeTeX and fooling polyglossia into loading luabidi in place of
bidi.

I have found that I can compile my real document now, and it seems ok. But
I am obviously concerned at a) using luaTeX for a production document,
given that lua documentation warns against it, b) pulling tricks on
polyglossia to get it to work, and c) the fact that I get "Package
polyglossia Warning: Hebrew is not supported with LuaTeX.   I will proceed
with the compilation, but the output is not guaranteed to be correct and
may look very wrong.²

I have searched but cannot find info on what the issue is with Hebrew and
luaTeX (my output so far seems fine). I wonder a number of things:

* Dare I proceed? (I rather need the RTL media buttonsŠ.)
* Why does this work with luabidi but not bidi? (or even, what¹s a likely
reasonŠ)
* What¹s the issue with Hebrew and luaTex?
* Is perhaps all of this likely to go away with the new XeTeX currently
under discussion?

Any insight at all on this would be appreciated. I follow the XeTeX
discussion with interest though I confess that the details are beyond me :)

Karljürgen G. Feuerherm, PhD | 2-139 Department of History | Wilfrid
Laurier University | 75 University Avenue West | Waterloo, Ontario N2L
3C5