Re: Mixed L2R and R2L paragraphs and horizontal scroll

[martin rudalics <rudalics@gmx.at>]

 > In a R2L line, columns should be numbered from the
 > right margin of the window.

Technically columns are numbered by counting characters following the
last newline in the buffer text.  Just that for R2L text you have to
jump to the end of the text first and then go back in the text.  Anyway,
column numbers are in the buffer text, unrelated to display or windows.
So I suppose you're using the term window margin as metaphor here.

 > Given the fact that a window's dimensions
 > can be changed at will, and thus the horizontal position of characters
 > in R2L lines relative to L2R lines can change, there simply isn't any
 > other reasonable way of numbering columns of a R2L line.  We will need
 > that anyway for supporting features like indentation and tab stops in
 > R2L paragraphs.

There is one thing I conceptually don't understand yet: When I currently
shrink the width of a window Emacs doesn't hide text at the left side of
the window but text at the right side may get truncated when the window
becomes too small.  Will this behavior be reverted for R2L text in the
sense that text at the left side is truncated?

 > And since the columns are numbered from the right margin, hscroll,
 > too, should scroll R2L lines to the right when L2R lines are hscrolled
 > to the left.  That's the only reasonable way of generalizing the
 > current unidirectional hscroll, IMO.  It also preserves the semantics
 > of window-hscroll (modulo the fact that R2L lines are scrolled from
 > the right margin, not the left one).
 >
 > Makes sense?

Sounds simple and robust.

martin