bug#18793: 24.4; zero width rectangular selection displaces text

[Drew Adams <drew.adams@oracle.com>]

> Drew Adams <drew.adams@oracle.com> writes:
> 
> > I suggested a simple solution that provides
> > feedback not only that an empty rectangle is
> > selected but continual feedback about any
> > rectangle selection.
> 
> I like the idea of using the mode line.
> 
> Then, what can one do with a zero-width region?  If just C-x r t, then
> we could (and should) indicate the region as multiple cursors, like
> other editors do.
> 
> Either way, +1 for no jiggle.

The answer is in `modeline-region.el', here:

https://www.emacswiki.org/emacs/download/modeline-region.el

It's described here:

https://www.emacswiki.org/emacs/ModeLineRegion

As for what indication you get for an empty but
active region: that's controlled by user option
`mlr-empty-region-flag'.  By default its value
is non-nil, which means that you see this in
the mode-line:

  0 lines, 0 chars

That's highlighted there with face `mlr-region',
which by default just inherits from face `region'.

If you customize the option to nil then you see
no mode-line indication that the region is empty
and activated.

(You still get the message "Mark set", of course,
when you use `C-SPC', so at least you get some
notification of that action.)