Re: [emacs-bidi] Mixed L2R and R2L paragraphs and horizontal scroll

[Richard Stallman]

    ??? What are the alternatives?  The only one that was raised is the
    ``rigid scrolling'', but even there we need to do something sensible
    for the nil value of ``line length''.

Rigid scrolling is the right thing to do.  As far as I can see, it is
simple and well defined in all cases, including the case where the
window width controls the normal alignment of R2L lines.

That case (which is the one you have implemented so far, right?)  is a
matter of how to display the text when there is no hscroll.  However,
what hscroll should do in that case is totally straightforward: just
scroll all the text (including the parts that are hidden off the left
and right edges) rigidly left or right.