Re: enriched-mode and switching major modes.

[Kai Grossjohann <kai@emptydomain.de>]

Richard Stallman <rms@gnu.org> writes:

> However, there are some details here that are nontrivial problems.
>
> 1. How to distinguish between two similar boxes with the same specs
> and a single longer box.

That's true.  Perhaps one could have a block-begin text property and a
block-end text property, both attached to the gap between two
characters?

> 2. How to represent line breaks.  Saying "break one long line at
> display time" would work ok for display, but all the commands that
> operate on lines would see just one long line there.

I think this is not too much of a problem.  Kim has done a great job
of changing the behavior of some Emacs commands to do cua-like
things.  I expect that a similar method would work to change the
behavior of beginning-of-line, next-line and so on.

> 3. How to represent indentation.  If the indentation appears only
> in redisplay, Lisp code that looks at the text will think it is not
> indented at all.

Here again, I think it is not a problem.  Why does the Lisp code need
to see the newline characters?  Why does it need to see the leading
whitespace?

Imagine that you have a feature which wraps long lines at word
boundaries at display time.  Imagine that this feature was configured
to wrap to the window width.  Now imagine that you make the window
narrower.  This introduces more wrapping points.  But which Lisp code
needs to see more newlines?

If we have source code, then we do need newline characters, but we're
talking about editing text.

Kai