Re: Mixed L2R and R2L paragraphs and horizontal scroll

 >> I meant a function which does (1) set such a variable
 >
 > You mean, besides "M-x set-variable RET"?

Yes, because it would have affected the appearance of text in one window
only.

 >> and (2) apply it to one or all windows showing a buffer.
 >
 > Currently, the variable is per-buffer, so it affects all the windows
 > showing that buffer.  Why would one need to do that only in some
 > windows showing a buffer?

I thought about giving users the possibility to work with a L2R
dominated view in one window and a R2L dominated one in another.  But if
I now understand your lock-step proposal correctly, these windows would
show the text in a similar fashion anyway.  So there seems no need to do
what I said.

martin