bug#30085: 25.2: Documentation for cua-rectangle-mark-mode

[Kim Storm <storm@cua.dk>]

On 2018-01-12 10:22, Eli Zaretskii wrote:
>> Date: Fri, 12 Jan 2018 02:14:26 -0500
>> From: Boruch Baum <boruch_baum@gmx.com>
>>
>> File `cua-rect.el' list its author as Kim F. Storm <storm@cua.dk>, so
>> I've taken the liberty of cc'ing the author on the bug report. @Kim:
>> Your work seems like a great improvement over emacs' documented
>> rectangle support, but seems to have remained relatively unknown due to
>> lack of documentation. It should be front and center in any search for
>> emacs rectangle support.
> Thanks for the comments.  Yes, cua-rect facilities are notoriously
> under-documented.  I would suggest that you (or someone else who uses
> cua-rect) propose specific patches to fix that, based on your
> experimenting with the facility and code reading.  IME, this will
> allow us to fill this gap much faster than any other alternative.
>
> Of course, Kim's contributions to this effort will also be very
> welcome.
>
Just a little history here:

In the original cua-mode file, everything was stashed together in
the same file, so I had to refactor the code before it was included
in Emacs 22.1

So I ended up adding three files: cua-base.el cua-gmrk.eland cua-rect.el
knowing that documentation for some of the more advanced stuff still
needed some improvements.

However, the other emacs maintainers insisted that the cua-rect.el stuff
didn't really have anything to do with cua-mode as such, but rather should
be merged into the existing rect.el code.

I agreed in principle, but didn't know how to accomplish that, so I left
it for someone else to do - and continued to work on other stuff.

Obviously, that merge never happened, and therefore, the more advanced
rectangle support in cua-rect stays inaccessible for those who don't
use cua-mode, and even for cua-mode users, some features are probably
not widely used due to lack of documentation.

So there are really two issues here:
  - merge cua-rect and rect code
  - complete documentation for the combined package

I might be able to contribute on the second item, but I still don't
know how to accomplish the first.