RE: Replacing huge hidden selection when pasting text

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

> > > Apologies for not following this thread.  But offhand I'd say that
> > > there's your problem right there: you enable `delete-selection-mode'
> > > but you disable `transient-mark-mode'.  That should be a no-no.
> >
> > Oh my dear, I managed to hit a no-no! But if it's a no-no why is it
> > possible in the first place? Why ain't there a single warning? Where
> > are emacs's no-nos listed? Where is the checkbox and message saying "I
> > agree not to do any emacs no-no, even if I don't know what they are"?
> > Are you serious?
> 
> I think there was much confusion in the thread, no doubt did the
> nihilistic tone of Alexandre inhibit a fruitful discussion.
> 
> Drew only wanted to help.  But I think he was wrong with what he said.
> I think it's ok to use the two modes at the same time.  In the sentence
> Drew cited:
> 
>  When Delete Selection mode is enabled, Transient Mark mode is also
>                                       ^^
>  enabled, typed text replaces the selection if the selection is active,
>  and DEL deletes the selection.
> 
> I think there is an "and" missing, and the sentence means something
> different from what we thought.

In fact, until Emacs 24.4, `delete-selection-mode' explicitly turned
on `transient-mark-mode', and the doc string was as I quoted it (and
it was correct).  No "and" was missing; t-m-mode was really enabled
by d-s-mode.  Emacs 24.3:

(if (not delete-selection-mode)
    (remove-hook 'pre-command-hook 'delete-selection-pre-hook)
  (add-hook 'pre-command-hook 'delete-selection-pre-hook)
  (transient-mark-mode t)) ; <=========

Starting with Emacs 24.4, d-s-mode no longer turns on t-m-mode.

> The current docstring (in my Emacs 25) says:
>   When Delete Selection mode is enabled, typed text replaces the
>   selection if the selection is active.  Otherwise, typed text is just
>   inserted at point regardless of any selection.
> 
> With `transient-mark-mode' off, you can mark a region (i.e., turn on
> transient mark mode temporarily) by hitting C-SPC twice.  Only then does
> delete-selection-mode replace the region.  In any other case (when the
> region is not visible, i.e. not active) transient-mark-mode is just off,
> and delete-selection-mode should not delete the region, never.

I think you are right.  This is not the original design of d-s-mode,
but was done when "temporary t-m-mode" was added (presumably precisely
to avoid the kind of gotcha that bit Alexandre).

> So I think the behavior he sometimes gets could indeed be a bug.  Would
> be good to have a bug report, and it would be good if Alexandre would
> try to find a recipe so that we can find out what's going on (this could
> also be caused by some add on package) and fix the issue when necessary.

Agreed.  (And maybe the doc string of `transient-mark-mode' should,
like the Emacs manual (node `Disabled Transient Mark'), mention
temporary activation of t-m-mode (via C-SPC C-SPC or C-u C-x C-x).