bug#29430: 26.0.90; C-M-backspace is undefined

bug#29430: 26.0.90; C-M-backspace is undefined

[Devon Sean McCullough]

C-M-DEL and ESC C-DEL should both run the same command.

<C-M-backspace> is undefined

ESC <C-backspace> (translated from <escape> <C-backspace>) runs the
command backward-kill-sexp (found in global-map), which is an
interactive compiled Lisp function in ‘lisp.el’.
It is bound to ESC <C-backspace>, ESC <C-delete>.

		Peace
			--Devon

P.S. Perhaps a missing translation?

M-DEL (translated from <M-backspace>) runs the command
backward-kill-word (found in global-map), which is an interactive
compiled Lisp function in ‘simple.el’.
It is bound to <C-backspace>, M-DEL.

In GNU Emacs 26.0.90 (build 1, x86_64-apple-darwin13.4.0, NS appkit-1265.21 Version 10.9.5 (Build 13F1911))
 of 2017-10-11 built on builder10-9.local
Windowing system distributor 'Apple', version 10.3.1404
Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Making completion list... [2 times]
backward-kill-sexp is on ESC <C-backspace>, ESC <C-delete>
Mark set
<C-M-backspace> is undefined
kill-region: Buffer is read-only: #<buffer *GNU Emacs*> [3 times]
Configured using:
 'configure --with-ns '--enable-locallisppath=/Library/Application
 Support/Emacs/${version}/site-lisp:/Library/Application
 Support/Emacs/site-lisp' --with-modules'

Configured features:
NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS MODULES

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
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Memory information:
((conses 16 204735 11575)
 (symbols 48 20073 1)
 (miscs 40 74 193)
 (strings 32 28896 1236)
 (string-bytes 1 754349)
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 (vector-slots 8 707316 10269)
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bug#29430: 26.0.90; C-M-backspace is undefined

[Noam Postavsky]

On Fri, Nov 24, 2017 at 2:12 PM, Devon Sean McCullough
<Emacs-Hacker2017@jovi.net> wrote:
> C-M-DEL and ESC C-DEL should both run the same command.
>
> <C-M-backspace> is undefined
>
> ESC <C-backspace> (translated from <escape> <C-backspace>) runs the
> command backward-kill-sexp (found in global-map), which is an
> interactive compiled Lisp function in ‘lisp.el’.
> It is bound to ESC <C-backspace>, ESC <C-delete>.
>
>                 Peace
>                         --Devon
>
> P.S. Perhaps a missing translation?

Seems to be on purpose, bindings.el:1236:

;;; These are dangerous in various situations,
;;; so let's not encourage anyone to use them.
;;;(define-key global-map [C-M-delete] 'backward-kill-sexp)
;;;(define-key global-map [C-M-backspace] 'backward-kill-sexp)

bug#29430: 26.0.90; C-M-backspace is undefined

[Devon Sean McCullough]

> On Nov 24, 2017, at 2:28 PM, Noam Postavsky <npostavs@users.sourceforge.net> wrote:
> Seems to be on purpose, bindings.el:1236:
> ;;; These are dangerous in various situations,
> ;;; so let's not encourage anyone to use them.
> ;;;(define-key global-map [C-M-delete] 'backward-kill-sexp)
> ;;;(define-key global-map [C-M-backspace] 'backward-kill-seep)

I doubt those historical reasons still hold
but let's be ultra-cautious — here's a minimal fix:

(unless (eq 'ns (window-system))
  ;; These were once dangerous in various situations,
  ;; so let's not encourage just anyone to use them.
  (define-key global-map [C-M-delete] 'backward-kill-sexp)
  (define-key global-map [C-M-backspace] 'backward-kill-sexp))

		Peace
			--Devon

P.S. Microsoft apparently considered Ctrl+Alt+Del a security feature,
laughably assuming it would be difficult for malware to intercept it
and steal passwords with a fake login screen.

P.P.S. X11 had a misfeature where Ctrl+Alt+Del nuked all your work
which has been disabled by default for years now in most situations,
e.g.,
    https://access.RedHat.com/documentation/en-us/red_hat_enterprise_linux/7/html/desktop_migration_and_administration_guide/enable-ctrl-alt-backspace
    https://AskUbuntu.com/questions/367983/how-do-i-enable-ctrl-alt-backspace-to-kill-the-x-server

P.P.P.S. As much as I condemn the imperious cyber-satan at One Infinite Loop,
they set mostly legal and licensing booby traps, seldom technical ones.

bug#29430: 26.0.90; C-M-backspace is undefined

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > (unless (eq 'ns (window-system))
  >   ;; These were once dangerous in various situations,
  >   ;; so let's not encourage just anyone to use them.
  >   (define-key global-map [C-M-delete] 'backward-kill-sexp)
  >   (define-key global-map [C-M-backspace] 'backward-kill-sexp))

It is not just on NextStep.
I think I saw one of these kill X windows on GNU/Linux.

-- 
Dr Richard Stallman
President, Free Software Foundation (https://gnu.org, https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)
Skype: No way! See https://stallman.org/skype.html.

bug#29430: 26.0.90; C-M-backspace is undefined

[Devon Sean McCullough]

> On Nov 25, 2017, at 6:14 PM, Richard Stallman <rms@gnu.org> wrote:
> It is not just on NextStep.
> I think I saw one of these kill X windows on GNU/Linux.

*BLUSH* I flipped a bit, here's the correct code:

(when (eq 'ns (window-system))
 ;; These were once dangerous in various situations,
 ;; so let's not encourage just anyone to use them.
 (define-key global-map [C-M-delete] 'backward-kill-sexp)
 (define-key global-map [C-M-backspace] 'backward-kill-seep))

We’ve all seen MS-Whatever's and X11’s peculiar responses to C-M-Del
— but not in recent years — however NeXTStep has always been immune.

		Peace
			—Devon

P.S. Perhaps the Emacs manual should have a stolen key chord appendix
with recipes for regaining and remapping keys under MS, NS, X11, etc., e.g.,

    MacOSX Apple Menu > System Preferences... > Keyboard > Keyboard > Modifier Keys...

has user preferences to put the <Control> keys next to the <Space> bar,
disable <CapsLock> and so on.  I even put <Rubout> left of <A>
by disabling <CapsLock> and configuring a third party app.

Gnu screen steals C-a so the -e switch deserves mention, e.g.,

    screen -e '^^^^'

sets the screen intercept character to Control-Caret
which Emacs conveniently reserves for that purpose,
Many "cloud"///////network sys admins use this a lot.

bug#37447: 26.3; Commands on <delete> and <backspace>

[Lars Ingebrigtsen]

Noam Postavsky <npostavs@users.sourceforge.net> writes:

> Seems to be on purpose, bindings.el:1236:
>
> ;;; These are dangerous in various situations,
> ;;; so let's not encourage anyone to use them.
> ;;;(define-key global-map [C-M-delete] 'backward-kill-sexp)
> ;;;(define-key global-map [C-M-backspace] 'backward-kill-sexp)

I've now reinstated the bindings, since X stopped killing itself if you
hit those keys decades ago (in all mainstream configurations).

The merged bug report discussed moving some of other related keys
around, and the conclusions was that we don't want to do that, so I'm
closing this bug report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#37447: 26.3; Commands on <delete> and <backspace>

[Drew Adams]

> > ;;; These are dangerous in various situations,
> > ;;; so let's not encourage anyone to use them.
> > ;;;(define-key global-map [C-M-delete] 'backward-kill-sexp)
> > ;;;(define-key global-map [C-M-backspace] 'backward-kill-sexp)
> 
> I've now reinstated the bindings, since X stopped killing itself if you
> hit those keys decades ago (in all mainstream configurations).

[C-M-delete] is problematic for MS Windows, no?

bug#37447: bug#29430: bug#37447: 26.3; Commands on <delete> and <backspace>

[Eli Zaretskii]

> Resent-From: Drew Adams <drew.adams@oracle.com>
> Original-Sender: "Debbugs-submit" <debbugs-submit-bounces@debbugs.gnu.org>
> Resent-CC: bug-gnu-emacs@gnu.org
> Resent-Sender: help-debbugs@gnu.org
> From: Drew Adams <drew.adams@oracle.com>
> Date: Wed, 23 Mar 2022 14:35:21 +0000
> Accept-Language: en-US
> Cc: Devon Sean McCullough <Emacs-Hacker2017@jovi.net>,
>  "37447@debbugs.gnu.org" <37447@debbugs.gnu.org>,
>  "29430@debbugs.gnu.org" <29430@debbugs.gnu.org>
> 
> > > ;;; These are dangerous in various situations,
> > > ;;; so let's not encourage anyone to use them.
> > > ;;;(define-key global-map [C-M-delete] 'backward-kill-sexp)
> > > ;;;(define-key global-map [C-M-backspace] 'backward-kill-sexp)
> > 
> > I've now reinstated the bindings, since X stopped killing itself if you
> > hit those keys decades ago (in all mainstream configurations).
> 
> [C-M-delete] is problematic for MS Windows, no?

Problematic in what sense?

bug#29430: Re: bug#29430: bug#37447: 26.3; Commands on <delete> and <backspace>

[Drew Adams]

> > [C-M-delete] is problematic for MS Windows, no?
> 
> Problematic in what sense?

By default, at least, it's grabbed by Windows.

I suppose you can use `w32-register-hot-key'
to wrestle it away from Windows.  But that's
a pretty important key for Windows, IME.

Not an expert.  Background (which I'm sure you,
at least, are familiar with):

https://en.wikipedia.org/wiki/Control-Alt-Delete

(I use `C-M-backspace' for `backward-kill-sexp'.
I use `Ctrl+Alt+Delete' for Windows.)

bug#29430: bug#37447: 26.3; Commands on <delete> and <backspace>

[Eli Zaretskii]

> From: Drew Adams <drew.adams@oracle.com>
> CC: "larsi@gnus.org" <larsi@gnus.org>,
>         "npostavs@users.sourceforge.net"
> 	<npostavs@users.sourceforge.net>,
>         "Emacs-Hacker2017@jovi.net"
> 	<Emacs-Hacker2017@jovi.net>,
>         "37447@debbugs.gnu.org" <37447@debbugs.gnu.org>,
>         "29430@debbugs.gnu.org" <29430@debbugs.gnu.org>
> Date: Wed, 23 Mar 2022 20:49:16 +0000
> 
> > > [C-M-delete] is problematic for MS Windows, no?
> > 
> > Problematic in what sense?
> 
> By default, at least, it's grabbed by Windows.

But that hasn't changed just because Emacs now has a binding to that
key, has it?  IOW, whatever problems Windows users had or didn't have
before the change, they still either have or don't have.

bug#37447: bug#29430: bug#37447: 26.3; Commands on <delete> and <backspace>

[Drew Adams]

> > > > [C-M-delete] is problematic for MS Windows, no?
> > >
> > > Problematic in what sense?
> >
> > By default, at least, it's grabbed by Windows.
> 
> But that hasn't changed just because Emacs now has a binding to that
> key, has it?  IOW, whatever problems Windows users had or didn't have
> before the change, they still either have or don't have.

Yes, of course.  But without binding it by default
users are less likely to suffer the gotcha.

Just mentioning that that binding can be a problem
for some Windows users.  If you feel it's important
to bind it by default, so be it.

bug#37447: bug#29430: bug#37447: 26.3; Commands on <delete> and <backspace>

[Eli Zaretskii]

> From: Drew Adams <drew.adams@oracle.com>
> CC: "larsi@gnus.org" <larsi@gnus.org>,
>         "npostavs@users.sourceforge.net"
> 	<npostavs@users.sourceforge.net>,
>         "Emacs-Hacker2017@jovi.net"
> 	<Emacs-Hacker2017@jovi.net>,
>         "37447@debbugs.gnu.org" <37447@debbugs.gnu.org>,
>         "29430@debbugs.gnu.org" <29430@debbugs.gnu.org>
> Date: Thu, 24 Mar 2022 15:16:32 +0000
> Accept-Language: en-US
> 
> > > > > [C-M-delete] is problematic for MS Windows, no?
> > > >
> > > > Problematic in what sense?
> > >
> > > By default, at least, it's grabbed by Windows.
> > 
> > But that hasn't changed just because Emacs now has a binding to that
> > key, has it?  IOW, whatever problems Windows users had or didn't have
> > before the change, they still either have or don't have.
> 
> Yes, of course.  But without binding it by default
> users are less likely to suffer the gotcha.

How so?  The probability of users using the key is independent of
whether Emacs does or doesn't define a key binding for it.  Besides,
who are those Windows users that don't know about Ctrl-Alt-Del
sequence, and are likely to use it without understanding what they
will get?

bug#37447: bug#29430: bug#37447: 26.3; Commands on <delete> and <backspace>

[Drew Adams]

> > > > > > [C-M-delete] is problematic for MS Windows, no?
> > > > >
> > > > > Problematic in what sense?
> > > >
> > > > By default, at least, it's grabbed by Windows.
> > >
> > > But that hasn't changed just because Emacs now has a binding to
> > > that key, has it?  IOW, whatever problems Windows users had or didn't
> > > have before the change, they still either have or don't have.
> >
> > Yes, of course.  But without binding it by default
> > users are less likely to suffer the gotcha.
> 
> How so?  The probability of users using the key is independent of
> whether Emacs does or doesn't define a key binding for it.  Besides,
> who are those Windows users that don't know about Ctrl-Alt-Del
> sequence, and are likely to use it without understanding what they
> will get?

Can we agree to disagree, or must we also disagree
about such agreement?

Emacs advertising this as a default binding might
just incite some Emacs users to try to use it, in
Emacs.  That's all.  Not a big deal.  Certainly
they'll find out soon enough...