RE: delete-selection-mode as default

[Drew Adams]

> > The secondary selection doesn't have all these problems, 
> > so it's a good example.
> 
> The secondary selection can only be defined by mouse gestures. 

In vanilla Emacs, yes. But not if you use `second-sel.el'.

You can define (set) it in several ways using the keyboard (suggested keys 
shown):

* Start secondary with `C-x C-M-SPC' (`set-secondary-start').
* End secondary with `C-x C-M-<return>' (`secondary-save-then-kill').
* Set secondary to the region by using a prefix arg with `C-M-y' 
(`secondary-yank|select|move|swap')

The last of these does multiple things, depending on the prefix arg:

* None: Yank secondary selection
* Zero: Select secondary as region. I.e., put region where secondary is.
* > 0:  Move secondary to region.
* < 0:  Swap region and secondary.

The last two of these are ways to set the secondary from the region.

So just as you can set the region in multiple ways, so can you set the 
secondary. Each way of setting the region gives you a way to set the secondary.