RE: delete-selection-mode as default

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

> It also leaves the issue of persistent selections.  Yuri and Drew said
> that it would be a huge amount of work, 

I don't think I said that (but I'm not going to search all that I've said
in this thread). I pointed out various things that could be done to
implement multiple persistent selections, in particular pointing to
what is already available in `second-sel.el' and `zones.el'.

> and Yuri explained how the
> appeal of persistent selections may be limited when multiple buffers and
> windows get involved.  I'd still like having that, but it doesn't really
> provide additional functionality other than the possibility of multiple
> persistent selections per buffer which I never missed --- and apparently
> can already have with zones, as Drew suggested.

To be clear, the zones in a set (list) of zones can be in the same
buffer, which might or might not be the current buffer, or they
can be in different buffers. You can have multiple sets (lists) of
zones, and any zone in any of them can have its limit positions
in any buffer.

The limits defining a given zone can be unspecified as to their
buffer, in which case that zone can be used in any buffer. The
only requirement on the two limits of a given zone is that if they
each specify a buffer then they must specify the same buffer
(otherwise the behavior is undefined).

Any zone limit can be an Emacs marker, a "readable marker"
(which can be saved to disk), or a positive integer.