GNU Emacs NEWS -- history of user-visible changes.

Copyright (C) 2017-2020 Free Software Foundation, Inc.
See the end of the file for license conditions.

Please send Emacs bug reports to 'bug-gnu-emacs@gnu.org'.
If possible, use 'M-x report-emacs-bug'.

This file is about changes in Emacs version 28.

See file HISTORY for a list of GNU Emacs versions and release dates.
See files NEWS.27, NEWS.26, ..., NEWS.18, and NEWS.1-17 for changes
in older Emacs versions.

You can narrow news to a specific version by calling 'view-emacs-news'
with a prefix argument or by typing 'C-u C-h C-n'.

Temporary note:
+++ indicates that all relevant manuals in doc/ have been updated.
--- means no change in the manuals is needed.
When you add a new item, use the appropriate mark if you are sure it
applies, and please also update docstrings as needed.

\f
* Installation Changes in Emacs 28.1

** Cairo graphics library is now used by default if found.
'--with-cairo' is now the default, if the appropriate development files
are found by 'configure'.  Note that building with Cairo means using
Pango instead of libXFT for font support.  Since Pango 1.44 has
removed support for bitmapped fonts, this may require you to adjust
your font settings.

Note also that 'FontBackend' settings in ".Xdefaults" or
".Xresources", or 'font-backend' frame parameter settings in your init
files, may need to be adjusted, as 'xft' is no longer a valid backend
when using Cairo.  Use 'ftcrhb' if your Emacs was built with HarfBuzz
text shaping support, and 'ftcr' otherwise.  You can determine this by
checking 'system-configuration-features'.  The 'ftcr' backend will
still be available when HarfBuzz is supported, but will not be used by
default.  We strongly recommend building with HarBuzz support.  'x' is
still a valid backend.

---
** Building without double buffering support.
'configure --with-xdbe=no' can now be used to disable double buffering
at build time.

---
** 'configure' now warns about building with libXft support.
libXft is unmaintained, and causes a number of problems with modern
fonts including but not limited to crashes; support for it may be
removed in a future version of Emacs.  Please consider using
Cairo + HarfBuzz instead.

---
** 'configure' now warns about not using HarfBuzz if using Cairo.
We want to encourage people to use the most modern font features
available, and this is the Cairo graphics library + HarfBuzz for font
shaping, so 'configure' now recommends that combination.

---
** The ftx font backend driver has been removed.
It was declared obsolete in Emacs 27.1.

---
** Support for building with '-fcheck-pointer-bounds' has been removed.
GCC has withdrawn the '-fcheck-pointer-bounds' option and support for
its implementation has been removed from the Linux kernel.

---
** Emacs no longer supports old OpenBSD systems.
OpenBSD 5.3 and older releases are no longer supported, as they lack
proper pty support that Emacs needs.

\f
* Startup Changes in Emacs 28.1

** Emacs can support 24-bit color TTY without terminfo database.
If your text-mode terminal supports 24-bit true color, but your system
lacks the terminfo database, you can instruct Emacs to support 24-bit
true color by setting 'COLORTERM=truecolor' in the environment.  This is
useful on systems such as FreeBSD which ships only with "etc/termcap".

\f
* Changes in Emacs 28.1

+++
** New variables that hold default buffer names for shell output.
The new constants 'shell-command-buffer-name' and
'shell-command-buffer-name-async' store the default buffer names
for the output of, respectively, synchronous and async shell
commands.

** Support for '(box . SIZE)' 'cursor-type'.
By default, 'box' cursor always has a filled box shape.  But if you
specify 'cursor-type' to be '(box . SIZE)', the cursor becomes a hollow
box if the point is on an image larger than 'SIZE' pixels in any
dimension.

+++
** New user option 'word-wrap-by-category'.
When word-wrap is enabled, and this option is non-nil, that allows
Emacs to break lines after more characters than just whitespace
characters.  In particular, this significantly improves word-wrapping
for CJK text mixed with Latin text.

---
** Improved language transliteration in Malayalam input methods.
Added a new Mozhi scheme.  The inapplicable ITRANS scheme is now
deprecated.  Errors in the Inscript method were corrected.

---
** Rudimentary support for the 'st' terminal emulator.
Emacs now supports 256 color display on the 'st' terminal emulator.

---
** Mouse wheel scrolling now works on more parts of frame's display.
When using 'mwheel-mode', the mouse wheel will now scroll also when
the mouse cursor is on the scroll bars, fringes, margins, header line,
and mode line.  ('mwheel-mode' is enabled by default on most graphical
displays.)

\f
* Editing Changes in Emacs 28.1

---
** 'eval-expression' now no longer signals an error on incomplete expressions.
Previously, typing 'M-: ( RET' would result in Emacs saying "End of
file during parsing" and dropping out of the minibuffer.  The user
would have to type 'M-: M-p' to edit and redo the expression.  Now
Emacs will echo the message and allow the user to continue editing.

+++
** New command 'undo-redo'.
It undoes previous undo commands, but doesn't record itself as an
undoable command.

+++
** 'read-number' now has its own history variable.
Additionally, the function now accepts a HIST argument which can be
used to specify a custom history variable.

+++
** Input history for 'goto-line' is now local to every buffer.
Each buffer will keep a separate history of line numbers used with
'goto-line'.  This should help making faster the process of finding
line numbers that were previously jumped to.

+++
** When 'suggest-key-bindings' is non-nil, the completion list of 'M-x'
shows equivalent key bindings for all commands that have them.

---
** Movement commands in 'gomoku-mode' are fixed.
'gomoku-move-sw' and 'gomoku-move-ne' now work correctly, and
horizontal movements now stop at the edge of the board.

** Autosaving via 'auto-save-visited-mode' can now be inhibited by
setting the variable 'auto-save-visited-mode' buffer-locally to nil.

** New commands to describe buttons and widgets have been added.
'widget-describe' (on a widget) will pop up a help buffer and give a
description of the properties.  Likewise 'button-describe' does the
same for a button.

\f
* Changes in Specialized Modes and Packages in Emacs 28.1

---
** Specific warnings can now be disabled from the warning buffer.
When a warning is displayed to the user, the resulting buffer now has
buttons which allow making permanent changes to the treatment of that
warning.  Automatic showing of the warning can be disabled (although
it is still logged to the *Messages* buffer), or the warning can be
disabled entirely.

** mspool.el

---
*** Autoload the main entry point 'mspool-show'.

** Windows

*** The key prefix 'C-x 4 1' displays next command buffer in the same window.
It's bound to the command 'same-window-prefix' that requests the buffer
of the next command to be displayed in the same window.

*** The key prefix 'C-x 4 4' displays next command buffer in a new window.
It's bound to the command 'other-window-prefix' that requests the buffer
of the next command to be displayed in a new window.

** Frames

*** The key prefix 'C-x 5 5' displays next command buffer in a new frame.
It's bound to the command 'other-frame-prefix' that requests the buffer
of the next command to be displayed in a new frame.

** Tab Bars

*** The key prefix 'C-x t t' displays next command buffer in a new tab.
It's bound to the command 'other-tab-prefix' that requests the buffer
of the next command to be displayed in a new tab.

*** The tab bar is frame-local when 'tab-bar-show' is a number.
Show/hide the tab bar independently for each frame, according to the
value of 'tab-bar-show'.

** New bindings in occur-mode, 'next-error-no-select' bound to 'n' and
'previous-error-no-select' bound to 'p'.

** EIEIO

+++
*** The macro 'oref-default' can now be used with 'setf'.
It is now defined as a generalized variable that can be used with
'setf' to modify the value stored in a given class slot.

** New minor mode 'cl-font-lock-built-in-mode' for 'lisp-mode'.
The mode provides refined highlighting of built-in functions, types,
and variables.

** Archive mode

*** Can now modify members of 'ar' archives.

*** Display of summaries unified between backends.

*** New user option 'archive-hidden-columns' and command
'archive-hideshow-column'.  These let you control which columns are
displayed and which are kept hidden.

---
*** New command bound to 'C': 'archive-copy-file'.
This command extracts the file under point and writes the data to a
file.

** Emacs Lisp mode

*** The mode-line now indicates whether we're using lexical or dynamic scoping.

*** A space between an open paren and a symbol changes the indentation rule.
The presence of a space between an open paren and a symbol now is
taken as a statement by the programmer that this should be indented
as a data list rather than as a piece of code.

** Calendar

+++
*** New user option 'calendar-time-zone-style'.
If 'numeric', calendar functions (eg 'calendar-sunrise-sunset') that display
time zones will use a form like "+0100" instead of "CET".

** Dired

---
*** Broken and circular links are shown with the 'dired-broken-symlink' face.

*** '=' ('dired-diff') will now put all backup files into the 'M-n' history.
When using '=' on a file with backup files, the default file to use
for diffing is the newest backup file.  You can now use 'M-n' to quickly
select a different backup file instead.

+++
*** New user option 'dired-maybe-use-globstar'.
If set, enables globstar (recursive globbing) in shells that support
this feature, but turn it off by default.  This allows producing
directory listings with files matching a wildcard in all the
subdirectories of a given directory.  The new variable
'dired-enable-globstar-in-shell' lists which shells can have globstar
enabled, and how to enable it.

+++
*** New user option 'dired-copy-dereference'.
If set to non-nil, Dired will dereference symbolic links when copying.
This can be switched off on a per-usage basis by providing
'dired-do-copy' with a 'C-u' prefix.

*** New user option 'dired-mark-region' affects all Dired commands
that mark files.  When non-nil and the region is active in Transient
Mark mode, then Dired commands operate only on files in the active
region.  The values 'file' and 'line' of this user option define the
details of marking the file at the end of the region.

*** State changing VC operations are supported in Dired on files and
directories with the help of new command 'dired-vc-next-action'.

** Change Logs and VC

*** More VC commands can be used from non-file buffers.
The relevant commands are those that don't change the VC state.
The non-file buffers which can use VC commands are those that have
their 'default-directory' under VC.

*** New command 'vc-dir-root' uses the root directory without asking.

*** New commands 'vc-dir-mark-registered-files' (bound to '* r') and
'vc-dir-mark-unregistered-files'.

*** Support for bookmark.el.
Bookmark locations can refer to VC directory buffers.

---
*** New user option 'vc-hg-create-bookmark'.
It controls whether a bookmark or branch will be created when you
invoke 'C-u C-x v s' ('vc-create-tag').

---
*** 'vc-hg' now uses 'hg summary' to populate extra 'vc-dir' headers.

---
*** New user option 'vc-git-revision-complete-only-branches'.
If non-nil, only branches and remotes are considered when doing
completion over Git branch names.  The default is nil, which causes
tags to be considered as well.

** Gnus

+++
*** New user option 'gnus-dbus-close-on-sleep'.
On systems with D-Bus support, it is now possible to register a signal
to close all Gnus servers before the system sleeps.

+++
*** The key binding of 'gnus-summary-search-article-forward' has changed.
This command was previously on 'M-s' and shadowed the global 'M-s'
search prefix.  The command has now been moved to 'M-s M-s'.  (For
consistency, the 'M-s M-r' key binding has been added for the
'gnus-summary-search-article-backward' command.)

---
*** The value of "all" in the 'large-newsgroup-initial' group parameter changes.
It was previously nil, which didn't work, because nil is
indistinguishable from not being present.  The new value for "all" is
the symbol 'all'.

+++
*** The name of dependent Gnus sessions has changed from "slave" to "child".
The names of the commands 'gnus-slave', 'gnus-slave-no-server' and
'gnus-slave-unplugged' have changed to 'gnus-child',
'gnus-child-no-server' and 'gnus-child-unplugged' respectively.

+++
*** The 'W Q' summary mode command now takes a numerical prefix to
allow adjusting the fill width.

+++
*** New variable 'mm-inline-font-lock'.
This variable is supposed to be bound by callers to determine whether
inline MIME parts (that support it) are supposed to be font-locked or
not.

** Message

+++
*** Message now supports the OpenPGP header.
To generate these headers, add the new function
'message-add-openpgp-header' to 'message-send-hook'.  The header will
be generated according to the new 'message-openpgp-header' variable.

---
*** A change to how "Mail-Copies-To: never" is handled.
If a user has specified "Mail-Copies-To: never", and Message was asked
to do a "wide reply", some other arbitrary recipient would end up in
the resulting "To" header, while the remaining recipients would be put
in the "Cc" header.  This is somewhat misleading, as it looks like
you're responding to a specific person in particular.  This has been
changed so that all the recipients are put in the "To" header in these
instances.

+++
*** New function to start Emacs in Message mode to send an email.
Emacs can be defined as a handler for the "x-scheme-handler/mailto"
MIME type with the following command: "emacs -f message-mailto %u".
An "emacs-mail.desktop" file has been included, suitable for
installing in desktop directories like "/usr/share/applications".
Clicking on a 'mailto:' link in other applications will then open
Emacs with headers filled out according to the link, e.g.
"mailto:larsi@gnus.org?subject=This+is+a+test".

---
*** Change to default value of 'message-draft-headers' user option.
The 'Date' symbol has been removed from the default value, meaning that
draft or delayed messages will get a date reflecting when the message
was sent.  To restore the original behavior of dating a message
from when it is first saved or delayed, add the symbol 'Date' back to
this user option.

+++
*** New command to take screenshots.
In Message mode buffers, the 'C-c C-p' ('message-insert-screenshot')
command has been added.  It depends on using an external program to
take the actual screenshot, and defaults to "ImageMagick import".

** Smtpmail

+++
*** Allow direct selection of smtp authentication mechanism.
A server entry retrieved by auth-source can request a desired smtp
authentication mechanism by setting a value for the key 'smtp-auth'.

** Help

+++
*** New command 'describe-keymap' describes keybindings in a keymap.

---
*** The command 'view-lossage' can now be invoked from the menu bar.
The menu-bar Help menu now has a "Show Recent Inputs" item under the
"Describe" sub-menu.

** Ispell

+++
*** 'ispell-comments-and-strings' now accepts START and END arguments,
defaulting to active region when used interactively.

+++
*** New command 'ispell-comment-or-string-at-point' is provided.

---
** The old non-SMIE indentation of 'sh-mode' has been removed.

---
** The sb-image.el library is now marked obsolete.
This file was a compatibility kludge which is no longer needed.

---
** Lisp mode now uses 'common-lisp-indent-function'.
To revert to the previous behavior,
'(setq lisp-indent-function 'lisp-indent-function)' from 'lisp-mode-hook'.

** Edebug

+++
*** Edebug specification lists can use the new keyword '&error', which
unconditionally aborts the current edebug instrumentation with the
supplied error message.

*** Edebug specification lists can use the new keyword ':unique',
which appends a unique suffix to the Edebug name of the current
definition.

+++
** ElDoc

*** New hook 'eldoc-documentation-functions'.
This hook is intended to be used for registering doc string functions.
These functions don't need to produce the doc string right away, they
may arrange for it to be produced asynchronously.  The results of all
doc string functions are accessible to the user through the user
option 'eldoc-documentation-strategy'.

*** New user option 'eldoc-documentation-strategy'.
The built-in choices available for this user option let users compose
the results of 'eldoc-documentation-functions' in various ways, even
if some of those functions are sychronous and some asynchchronous.
The user option replaces 'eldoc-documentation-function', which is now
obsolete.

*** 'eldoc-echo-area-use-multiline-p' is now handled by ElDoc.
The user option 'eldoc-echo-area-use-multiline-p' is now handled
by the ElDoc library itself.  Functions in
'eldoc-documentation-functions' don't need to worry about consulting
it when producing a doc string.

** Eshell

---
*** Environment variable 'INSIDE_EMACS' is now copied to subprocesses.
Its value equals the result of evaluating '(format "%s,eshell" emacs-version)'.

---
*** Eshell no longer re-initializes its keymap every call.
This allows users to use (define-key eshell-mode-map ...) as usual.
Some modules have their own minor mode now to account for these
changes.

** EUDC

+++
*** New macOS Contacts backend.
This backend works on newer versions of macOS and is generally
preferred over the eudcb-mab.el backend.

** Tramp

+++
*** New connection method "media", which allows accessing media devices
like cell phones, tablets or cameras.

+++
*** New command 'tramp-crypt-add-directory'.
This command marks a remote directory to contain only encrypted files.
See the "(tramp) Keeping files encrypted" node of the Tramp manual for
details.  This feature is experimental.

+++
*** Support of direct asynchronous process invocation.
When Tramp connection property "direct-async-process" is set to
non-nil for a given connection, 'make-process' and 'start-file-process'
calls are performed directly as in "ssh ... <command>".  This avoids
initialization performance penalties.  See the "(tramp) Improving
performance of asynchronous remote processes" node of the Tramp manual
for details, and also for a discussion or restrictions.  This feature
is experimental.

** Tempo

---
*** 'tempo-define-template' can now re-assign templates to tags.
Previously, assigning a new template to an already defined tag had no
effect.

** map.el

*** Pcase 'map' pattern added keyword symbols abbreviation.
A pattern like '(map :sym)' binds the map's value for ':sym' to 'sym',
equivalent to '(map (:sym sym))'.

** Package

+++
*** New functions to filter the package list.
The filter command key bindings are as follows:

key             binding
---             -------
/ a             package-menu-filter-by-archive
/ k             package-menu-filter-by-keyword
/ n             package-menu-filter-by-name
/ s             package-menu-filter-by-status
/ v             package-menu-filter-by-version
/ m             package-menu-filter-marked
/ /             package-menu-filter-clear

---
*** Column widths in 'list-packages' display can now be customized.
See the new user options 'package-name-column-width',
'package-version-column-width', 'package-status-column-width', and
'package-archive-column-width'.

** gdb-mi

+++
*** gdb-mi can now store and restore window configurations.
Use 'gdb-save-window-configuration' to save window configuration to a
file and 'gdb-load-window-configuration' to load from a file.  These
commands can also be accessed through the menu bar under 'Gud --
GDB-Windows'.  'gdb-default-window-configuration-file', when non-nil,
is loaded when GDB starts up.

+++
*** gdb-mi can now restore window configuration after quit.
Set 'gdb-restore-window-configuration-after-quit' to non-nil and Emacs
will remember the window configuration before GDB started and restore
it after GDB quits.  A toggle button is also provided under 'Gud --
GDB-Windows'.

+++
*** gdb-mi now has a better logic for displaying source buffers.
Now GDB only uses one source window to display source file by default.
Customize 'gdb-max-source-window-count' to use more than one window.
Control source file display by 'gdb-display-source-buffer-action'.

** Gravatar

---
*** New user option 'gravatar-service' for host to query for gravatars.
Defaults to 'libravatar', with 'unicornify' and 'gravatar' as options.

** Compilation mode

*** Regexp matching of messages is now case-sensitive by default.
The variable 'compilation-error-case-fold-search' can be set for
case-insensitive matching of messages when the old behavior is
required, but the recommended solution is to use a correctly matching
regexp instead.

---
*** Messages from Visual Studio that mention column numbers are now recognized.

** Hi Lock mode

---
*** Matching in 'hi-lock-mode' is case-sensitive when regexp contains
upper case characters and 'search-upper-case' is non-nil.
'highlight-phrase' also uses 'search-whitespace-regexp'
to substitute spaces in regexp search.

---
*** The default value of 'hi-lock-highlight-range' was enlarged.
The new default value is 2000000 (2 megabytes).

** Whitespace mode

+++
*** New style 'missing-newline-at-eof'.
If present in 'whitespace-style' (as it is by default), the final
character in the buffer will be highlighted if the buffer doesn't end
with a newline.

** Texinfo

---
*** New user option 'texinfo-texi2dvi-options'.
This is used when invoking 'texi2dvi' from 'texinfo-tex-buffer'.

---
*** New commands for moving in and between environments.
An "environment" is something that ends with '@end'.  The commands are
'C-c C-c C-f' (next end), 'C-c C-c C-b' (previous end),
'C-c C-c C-n' (next start) and 'C-c C-c C-p' (previous start), as well
as 'C-c .', which will alternate between the start and the end of the
current environment.

** Rmail

---
*** New user option 'rmail-re-abbrevs'.
Its default value matches localized abbreviations of the "reply"
prefix on the Subject line in various languages.

** Apropos

*** New commands 'apropos-next-symbol' and 'apropos-previous-symbol'.
These new navigation commands are bound to 'n' and 'p' in
'apropos-mode'.

*** New command 'apropos-function'.
This works like 'C-u M-x apropos-command' but is more discoverable.

** CC Mode

*** Added support for Doxygen documentation style.
'doxygen' is now a valid 'c-doc-comment-style' which recognises all
comment styles supported by Doxygen (namely '///', '//!', '/** … */'
and '/*! … */'.  'gtkdoc' remains the default for C and C++ modes; to
use 'doxygen' by default one might evaluate:

    (setq-default c-doc-comment-style
                  '((java-mode . javadoc)
                    (pike-mode . autodoc)
                    (c-mode    . doxygen)
                    (c++-mode  . doxygen)))

or use it in a custom 'c-style'.

*** Added support to line up '?' and ':' of a ternary operator.
The new 'c-lineup-ternary-bodies' function can be used as a lineup
function to align question mark and colon which are part of a ternary
operator ('?:').  For example:

    return arg % 2 == 0 ? arg / 2
                        : (3 * arg + 1);

To enable, add it to appropriate entries in 'c-offsets-alist', e.g.:

    (c-set-offset 'arglist-cont '(c-lineup-ternary-bodies
                                  c-lineup-gcc-asm-reg))
    (c-set-offset 'arglist-cont-nonempty '(c-lineup-ternary-bodies
                                           c-lineup-gcc-asm-reg
                                           c-lineup-arglist))
    (c-set-offset 'statement-cont '(c-lineup-ternary-bodies +))

** browse-url

*** Added support for custom URL handlers.
There is a new variable 'browse-url-default-handlers' and a user
option 'browse-url-handlers' being alists with '(REGEXP-OR-PREDICATE
. FUNCTION)' entries allowing to define different browsing FUNCTIONs
depending on the URL to be browsed.  The variable is for default
handlers provided by Emacs itself or external packages, the user
option is for the user (and allows for overriding the default
handlers).

Formerly, one could do the same by setting
'browse-url-browser-function' to such an alist.  This usage is still
supported but deprecated.

*** Categorization of browsing functions in internal vs. external.
All standard browsing functions such as 'browse-url-firefox',
'browse-url-mail', or 'eww' have been categorized into internal (URL
is browsed in Emacs) or external (an external application is spawned
with the URL).  This is done by adding a 'browse-url-browser-kind'
symbol property to the browsing functions.  With a new command
'browse-url-with-browser-kind', an URL can explicitly be browsed with
either an internal or external browser.

*** Support for the conkeror browser is now obsolete.

*** Support for the Mosaic browser has been removed.
This support has been obsolete since 25.1.

** SHR

---
*** The command 'shr-browse-url' now supports custom mailto handlers.
Clicking on or otherwise following a 'mailto:' link in a HTML buffer
rendered by SHR previously invoked the command 'browse-url-mailto'.
This is still the case by default, but if you customize
'browse-url-mailto-function' or 'browse-url-handlers' to call some
other function, it will now be called instead of the default.

+++
*** New user option 'shr-max-width'.
If this user option is non-nil, and 'shr-width' is nil, then SHR will
use the value of 'shr-max-width' to limit the width of the rendered
HTML.  The default is 120 characters, so even if you have very wide
frames, HTML text will be rendered more narrowly, which usually leads
to a more readable text.  Set this user option to nil to get the
previous behavior of rendering as wide as the 'window-width' allows.
If 'shr-width' is non-nil, it overrides this variable.

** Images

---
*** Animated images stop automatically under high CPU pressure sooner.
Previously, an animated image would stop animating if any single image
took more than two seconds to display.  The new algorithm maintains a
decaying average of delays, and if this number gets too high, the
animation is stopped.

+++
*** The 'n' and 'p' commands (next/previous image) now respects dired order.
These commands would previously display the next/previous image in
alphabetical order, but will now find the "parent" dired buffer and
select the next/previous image file according to how the files are
sorted there.  The commands have also been extended to work when the
"parent" buffer is an archive mode (i.e., zip file or the like) or tar
mode buffer.

---
*** 'image-converter' is now restricted to formats in 'auto-mode-alist'.
When using external image converters, the external program is queried
for what formats it supports.  This list may contain formats that are
problematic in some contexts (like PDFs), so this list is now filtered
based on 'auto-mode-alist'.  Only file names that map to 'image-mode'
are now supported.

---
*** The background and foreground of images now default to face colors.
When an image doesn't specify a foreground or background color, Emacs
now uses colors from the face used to draw the surrounding text
instead of the frame's default colors.

To load images with the default frame colors use the ':foreground' and
':background' image attributes, for example:

    (create-image "filename" nil nil
                  :foreground (face-attribute 'default :foreground)
                  :background (face-attribute 'default :background))

This change only affects image types that support foreground and
background colors or transparency, such as xbm, pbm, svg, png and gif.

** EWW

+++
*** New Emacs command line convenience function.
The 'eww-browse' command has been added, which allows you to register
Emacs as a MIME handler for "text/x-uri", and will call 'eww' on the
supplied URL.  Usage example: "emacs -f eww-browse https://gnu.org".

+++
*** 'eww-download-directory' will now use the XDG location, if defined.
However, if "~/Downloads/" already exists, that will continue to be
used.

---
*** The command 'eww-follow-link' now supports custom mailto handlers.
The function that is invoked when clicking on or otherwise following a
'mailto:' link in an EWW buffer can now be customized.  For more
information, see the related entry about 'shr-browse-url' above.

** Project

*** New user option 'project-vc-merge-submodules'.

*** Project commands now have their own history.
Previously used project directories are now suggested by all commands
that prompt for a project directory.

+++
*** New prefix keymap 'project-prefix-map'.
Key sequences that invoke project-related commands start with the
prefix 'C-x p'.  Type "C-x p C-h" to show the full list.

+++
*** New commands 'project-dired', 'project-vc-dir', 'project-shell',
'project-eshell'.  These commands run Dired/VC-Dir and Shell/Eshell in
a project's root directory, respectively.

+++
*** New command 'project-compile'.
This command runs compilation in the current project's root
directory.

+++
*** New command 'project-switch-project'.
This command lets you "switch" to another project and run a project
command chosen from a dispatch menu.

+++
*** New commands 'project-shell-command' and 'project-async-shell-command'.
These commands run 'shell-command' and 'async-shell-command' in a
project's root directory, respectively.

+++
*** New user option 'project-list-file'.

** json.el

---
*** JSON number parsing is now stricter.
Numbers with a leading plus sign, leading zeros, or a missing integer
component are now rejected by 'json-read' and friends.  This makes
them more compliant with the JSON specification and consistent with
the native JSON parsing functions.

** xml.el

*** XML serialization functions now reject invalid characters.
Previously 'xml-print' would produce invalid XML when given a string
with characters that are not valid in XML (see
https://www.w3.org/TR/xml/#charsets).  Now it rejects such strings.

** erc

---
*** The '/ignore' command will now ask for a timeout to stop ignoring the user.
Allowed inputs are seconds or ISO8601-like periods like "1h" or "4h30m".

---
*** ERC now recognizes 'C-]' for italic text.
Italic text is displayed in the new 'erc-italic-face'.

---
*** The erc-compat.el library is now marked obsolete.
This file contained ERC compatibility code for Emacs 21 and XEmacs
which is no longer needed.

---
*** erc-match.el now supports 'message' highlight type (not including the nick).
The 'erc-current-nick-highlight-type', 'erc-pal-highlight-type',
'erc-fool-highlight-type', 'erc-keyword-highlight-type', and
'erc-dangerous-host-highlight-type' variables now support a 'message'
type for highlighting the entire message but not the sender's nick.

** Battery

---
*** UPower is now the default battery status backend when available.
UPower support via the function 'battery-upower' was added in Emacs
26.1, but was disabled by default.  It is now the default value of
'battery-status-function' when the system provides a UPower D-Bus
service.  The user options 'battery-upower-device' and
'battery-upower-subscribe' control which power sources to query and
whether to respond to status change notifications in addition to
polling, respectively.

---
*** A richer syntax can be used to format battery status information.
The user options 'battery-mode-line-format' and
'battery-echo-area-format' now support the full formatting syntax of
the function 'format-spec' documented under node "(elisp) Custom Format
Strings".  The new syntax includes specifiers for padding and
truncation, amongst other things.

** bug-reference.el

---
*** Bug reference mode auto-setup.  If 'bug-reference-mode' or
'bug-reference-prog-mode' have been activated, their respective hook
has been run and still 'bug-reference-bug-regexp' and
'bug-reference-url-format' aren't both set, it tries to guess
appropriate values for those two variables.  There are three guessing
mechanisms so far: based on version control information of the current
buffer's file, based on newsgroup/mail-folder name and several news
and mail message headers in Gnus buffers, and based on IRC channel and
network in rcirc and ERC buffers.  All mechanisms are extensible with
custom rules, see the variables 'bug-reference-setup-from-vc-alist',
'bug-reference-setup-from-mail-alist', and
'bug-reference-setup-from-irc-alist'.

** HTML Mode

---
*** A new skeleton for adding relative URLs has been added.
It's bound to the 'C-c C-c f' keystroke, and prompts for a local file
name.

---
** Recentf
The recentf files are no longer backed up.

** Calc

---
*** The behavior when doing forward-delete has been changed.
Previously, using the 'C-d' command would delete the final number in
the input field, no matter where point was.  This has been changed to
work more traditionally, with 'C-d' deleting the next character.
Likewise, point isn't moved to the end of the string before inserting
digits.

** term-mode

---
*** New user option 'term-scroll-snap-to-bottom'.
By default, 'term' and 'ansi-term' will now recenter the buffer so
that the prompt is on the final line in the window.  Setting this new
user option to nil inhibits this behavior.

---
*** New user option 'term-set-terminal-size'
If non-nil, the 'LINES' and 'COLUMNS' environment variables will be set
based on the current window size.  In previous versions of Emacs, this
was always done (and that could lead to odd displays when resizing the
window after starting).  This variable defaults to nil.

** Miscellaneous

+++
*** The user can now customize how "default" values are prompted for.
The new utility function 'format-prompt' has been added which uses the
new 'minibuffer-default-prompt-format' user option to format "default"
prompts.  This means that prompts that look like "Enter a number
(default 10)" can be customized to look like, for instance, "Enter a
number [10]", or not have the default displayed at all, like "Enter a
number".  (This requires that all callers are altered to use
'format-prompt', though.)

---
*** New 'diff-mode' font locking face 'diff-error'.
This face is used for error messages from diff.

+++
*** New global mode 'global-goto-address-mode'.
This will enable 'goto-address-mode' in all buffers.

---
*** 'C-s' in 'M-x' now searches over completions again.
In Emacs 23, typing 'M-x' ('read-extended-command') and then 'C-s' (to
do an interactive search) would search over possible completions.
This was lost in Emacs 24, but is now back again.

---
*** 'M-x report-emacs-bug' will no longer include "Recent messages" section.
These were taken from the "*Messages*" buffer, and may inadvertently
leak information from the reporting user.

---
*** 'count-windows' now takes an optional parameter ALL-FRAMES.
The semantics are as with 'walk-windows'.

---
*** Killing virtual ido buffers interactively will make them go away.
Previously, killing a virtual ido buffer with 'ido-kill-buffer' didn't
do anything.  This has now been changed, and killing virtual buffers
with that command will remove the buffer from recentf.

---
*** New variable 'ffap-file-name-with-spaces'.
If non-nil, 'find-file-at-point' and friends will try to guess more
expansively to identify a file name with spaces.

---
*** Two new commands for centering in 'doc-view-mode'.
The new commands 'doc-view-center-page-horizontally' (bound to 'c h')
and 'doc-view-center-page-vertically' (bound to 'c v') center the page
horizontally and vertically, respectively.

---
*** Change in meaning of 'icomplete-show-matches-on-no-input'.
Previously, choosing a different completion with commands like 'C-.'
and then hitting 'RET' would choose the default completion.  Doing this
will now choose the completion under point instead.

---
*** The width of the buffer-name column in 'list-buffers' is now dynamic.
The width now depends of the width of the window, but will never be
wider than the length of the longest buffer name, except that it will
never be narrower than 19 characters.

*** Bookmarks can now be targets for new tabs.
When the bookmark.el library is loaded, a customize choice is added
to 'tab-bar-new-tab-choice' for new tabs to show the bookmark list.

** xwidget-webkit mode

*** New xwidget functions.
'xwidget-webkit-uri' (return the current URL), 'xwidget-webkit-title'
(return the current title), and 'xwidget-webkit-goto-history' (goto a
point in history).

*** Pixel-based scrolling.
The 'xwidget-webkit-scroll-up', 'xwidget-webkit-scroll-down' commands
now supports scrolling arbitrary pixel values.  It now treats the
optional 2nd argument as the pixel values to scroll.

*** New commands for scrolling.
The new commands 'xwidget-webkit-scroll-up-line',
'xwidget-webkit-scroll-down-line', 'xwidget-webkit-scroll-forward',
'xwidget-webkit-scroll-backward' can be used to scroll webkit by the
height of lines or width of chars.

*** New user option 'xwidget-webkit-bookmark-jump-new-session'.
When non-nil, use a new xwidget webkit session after bookmark jump.
Otherwise, it will use 'xwidget-webkit-last-session'.

** Flyspell mode

+++
*** Corrections and actions menu can be optionally bound to 'mouse-3'.
When Flyspell mode highlights a word as misspelled, you can click on
it to display a menu of possible corrections and actions.  You can now
easily bind this menu to 'down-mouse-3' (usually the right mouse button)
instead of 'mouse-2' (the default) by customizing the new user option
'flyspell-use-mouse-3-for-menu'.

** Time

---
*** 'display-time-world' has been renamed to 'world-clock'.
'world-clock' creates a buffer with an updating time display using
several time zones.  It is hoped that the new names are more
discoverable.

The following functions have been renamed:

  'display-time-world'         to 'world-clock'
  'display-time-world-mode'    to 'world-clock-mode'
  'display-time-world-display' to 'world-clock-display'
  'display-time-world-timer'   to 'world-clock-update'

The following user options have been renamed:

  'display-time-world-list'         to 'world-clock-list'
  'display-time-world-time-format'  to 'world-clock-time-format'
  'display-time-world-buffer-name'  to 'world-clock-buffer-name'
  'display-time-world-timer-enable' to 'world-clock-timer-enable'
  'display-time-world-timer-second' to 'world-clock-timer-second'

The old names are now obsolete.

** D-Bus

+++
*** Registered properties can have the new access type ':write'.

+++
*** In case of problems, handlers can emit proper D-Bus error messages now.

\f
* New Modes and Packages in Emacs 28.1

** Lisp Data mode

The new command 'lisp-data-mode' enables a major mode for buffers
composed of Lisp symbolic expressions that do not form a computer
program.  The ".dir-locals.el" file is automatically set to use this
mode, as are other data files produced by Emacs.

** hierarchy.el

It's a library to create, query, navigate and display hierarchy structures.

** New themes 'modus-vivendi' and 'modus-operandi'.
These themes are designed for colour-contrast accessibility.  You can
load the new themes using 'M-x customize-themes' or 'load-theme' from
your init file.

\f
* Incompatible Editing Changes in Emacs 28.1

** In 'nroff-mode', 'center-line' is now bound to 'M-o M-s'.
The original key binding was 'M-s', which interfered with I-search,
since the latter uses 'M-s' as a prefix key of the search prefix map.

** 'vc-print-branch-log' shows the change log for BRANCH from its root
directory instead of the default directory.

\f
* Incompatible Lisp Changes in Emacs 28.1

** 'equal' no longer examines some contents of window configurations.
Instead, it considers window configurations to be equal only if they
are 'eq'.  To compare contents, use 'compare-window-configurations'
instead.  This change helps fix a bug in 'sxhash-equal', which returned
incorrect hashes for window configurations and some other objects.

** When its first argument is a string, 'make-text-button' no longer
modifies the string's text properties; instead, it uses and returns
a copy of the string.  This helps avoid trouble when strings are
shared or constants.

---
** The obsolete function 'thread-alive-p' has been removed.

** 'dns-query' now consistently uses Lisp integers to represent integers.
Formerly it made an exception for integer components of SOA records,
because SOA serial numbers can exceed fixnum ranges on 32-bit platforms.
Emacs now supports bignums so this old glitch is no longer needed.

---
** The new function 'dns-query-asynchronous' has been added.
It takes the same parameters as 'dns-query', but adds a callback
parameter.

** The Lisp variables 'previous-system-messages-locale' and
'previous-system-time-locale' have been removed, as they were created
by mistake and were not useful to Lisp code.

** The 'load-dangerous-libraries' variable is now obsolete.
It was used to allow loading Lisp libraries compiled by XEmacs, a
modified version of Emacs which is no longer actively maintained.
This is no longer supported, and setting this variable has no effect.

+++
** The macro 'with-displayed-buffer-window' is now obsolete.
Use macro 'with-current-buffer-window' with action alist entry 'body-function'.

** The metamail.el library is now marked obsolete.

---
** Some obsolete variable and function aliases in dbus.el have been removed.
In Emacs 24.3, the variable 'dbus-event-error-hooks' was renamed to
'dbus-event-error-functions' and the function
'dbus-call-method-non-blocking' was renamed to 'dbus-call-method'.
The old names, which were kept as obsolete aliases of the new names,
have now been removed.

---
** Some libraries obsolete since Emacs 23 have been removed:
ledit.el, lmenu.el, lucid.el and old-whitespace.el.

---
** Some functions and variables obsolete since Emacs 23 have been removed:
'GOLD-map', 'advertised-xscheme-send-previous-expression',
'allout-init', 'bookmark-jump-noselect',
'bookmark-read-annotation-text-func', 'buffer-menu-mode-hook',
'c-forward-into-nomenclature', 'char-coding-system-table',
'char-valid-p', 'charset-bytes', 'charset-id', 'charset-list',
'choose-completion-delete-max-match', 'complete-in-turn',
'completion-base-size', 'completion-common-substring',
'crm-minibuffer-complete', 'crm-minibuffer-complete-and-exit',
'crm-minibuffer-completion-help', 'custom-mode', 'custom-mode-hook',
'define-mode-overload-implementation', 'detect-coding-with-priority',
'dirtrack-debug', 'dirtrack-debug-toggle', 'dynamic-completion-table',
'easy-menu-precalculate-equivalent-keybindings',
'epa-display-verify-result', 'epg-passphrase-callback-function',
'eshell-report-bug', 'eval-next-after-load', 'exchange-dot-and-mark',
'ffap-bug', 'ffap-submit-bug', 'ffap-version',
'file-cache-choose-completion', 'forward-point', 'generic-char-p',
'global-highlight-changes', 'hi-lock-face-history',
'hi-lock-regexp-history', 'highlight-changes-active-string',
'highlight-changes-initial-state', 'highlight-changes-passive-string',
'image-mode-maybe', 'imenu-example--name-and-position',
'ispell-aspell-supports-utf8', 'lisp-mode-auto-fill',
'locate-file-completion', 'make-coding-system',
'minibuffer-local-must-match-filename-map', 'mouse-choose-completion',
'mouse-major-mode-menu', 'mouse-popup-menubar',
'mouse-popup-menubar-stuff', 'newsticker-groups-filename',
'non-iso-charset-alist', 'nonascii-insert-offset',
'nonascii-translation-table', 'password-read-and-add',
'pre-abbrev-expand-hook', 'princ-list', 'print-help-return-message',
'process-filter-multibyte-p', 'read-file-name-predicate',
'remember-buffer', 'rmail-highlight-face', 'rmail-message-filter',
'semantic-after-idle-scheduler-reparse-hooks',
'semantic-after-toplevel-bovinate-hook',
'semantic-before-idle-scheduler-reparse-hooks',
'semantic-before-toplevel-bovination-hook',
'semantic-bovinate-from-nonterminal-full',
'semantic-bovinate-region-until-error', 'semantic-bovinate-toplevel',
'semantic-bovination-working-type',
'semantic-decorate-pending-decoration-hooks',
'semantic-edits-incremental-reparse-failed-hooks',
'semantic-eldoc-current-symbol-info', 'semantic-expand-nonterminal',
'semantic-file-token-stream', 'semantic-find-dependency',
'semantic-find-nonterminal', 'semantic-flex', 'semantic-flex-buffer',
'semantic-flex-keyword-get', 'semantic-flex-keyword-p',
'semantic-flex-keyword-put', 'semantic-flex-keywords',
'semantic-flex-list', 'semantic-flex-make-keyword-table',
'semantic-flex-map-keywords', 'semantic-flex-token-end',
'semantic-flex-token-start', 'semantic-flex-token-text',
'semantic-imenu-bucketize-type-parts',
'semantic-imenu-expand-type-parts', 'semantic-imenu-expandable-token',
'semantic-init-db-hooks)', 'semantic-init-hooks',
'semantic-init-mode-hooks', 'semantic-java-prototype-nonterminal',
'semantic-nonterminal-abstract', 'semantic-nonterminal-full-name',
'semantic-nonterminal-leaf', 'semantic-nonterminal-protection',
'semantic-something-to-stream', 'semantic-tag-make-assoc-list',
'semantic-token-type-parent', 'semantic-toplevel-bovine-cache',
'semantic-toplevel-bovine-table', 'semanticdb-mode-hooks',
'set-coding-priority', 'set-process-filter-multibyte',
'shadows-compare-text-p', 'shell-dirtrack-toggle', 't-mouse-mode',
'term-dynamic-simple-complete', 'tooltip-hook', 'tpu-have-ispell',
'url-generate-unique-filename', 'url-temporary-directory',
'vc-arch-command', 'vc-default-working-revision' (variable),
'vc-mtn-command', 'vc-revert-buffer', 'vc-workfile-version',
'vcursor-toggle-vcursor-map', 'w32-focus-frame', 'w32-select-font',
'wisent-lex-make-token-table'.

\f
* Lisp Changes in Emacs 28.1

+++
*** New function 'file-backup-file-names'.
This function returns the list of file names of all the backup files
of its file argument.

+++
** The 'count-lines' function now takes an optional parameter to
ignore invisible lines.

---
** 'count-words' now crosses field boundaries.
Originally, 'count-words' would stop counting at the first field
boundary it encountered; now it keeps counting all the way to the
region's (or buffer's) end.

---
** New function 'custom-add-choice'.
This function can be used by modes to add elements to the
'choice' customization type of a variable.

+++
** New function 'file-modes-number-to-symbolic' to convert a numeric
file mode specification into symbolic form.

** New macro 'dlet' to dynamically bind variables.

** The variable 'force-new-style-backquotes' has been removed.
This removes the final remaining trace of old-style backquotes.

** The module header 'emacs-module.h' now contains type aliases
'emacs_function' and 'emacs_finalizer' for module functions and
finalizers, respectively.

** Module functions can now install an optional finalizer that is
called when the function object is garbage-collected.  Use
'set_function_finalizer' to set the finalizer and
'get_function_finalizer' to retrieve it.

** Modules can now open a channel to an existing pipe process using
the new module function 'open_channel'.  Modules can use this
functionality to asynchronously send data back to Emacs.

** 'file-modes', 'set-file-modes', and 'set-file-times' now have an
optional argument specifying whether to follow symbolic links.

** 'parse-time-string' can now parse ISO 8601 format strings,
such as "2020-01-15T16:12:21-08:00".

---
** The new function 'decoded-time-period' has been added.
It interprets a decoded time structure as a period and returns the
equivalent period in seconds.

+++
** The new function 'dom-remove-attribute' has been added.

+++
** The new function 'dom-print' has been added.

---
** 'make-network-process', 'make-serial-process' ':coding' behavior change.
Previously, passing ':coding nil' to either of these functions would
override any non-nil binding for 'coding-system-for-read' and
'coding-system-for-write'.  For consistency with 'make-process' and
'make-pipe-process', passing ':coding nil' is now ignored.  No code in
Emacs depended on the previous behavior; if you really want the
process' coding-system to be nil, use 'set-process-coding-system'
after the process has been created, or pass in ':coding '(nil nil)'.

+++
** 'open-network-stream' now accepts a ':coding' argument.
This allows specifying the coding systems used by a network process
for encoding and decoding without having to bind
'coding-system-for-{read,write}' or call 'set-process-coding-system'.

+++
** 'open-network-stream' can now take a ':capability-command' that's a function.
The function is called with the greeting from the server as its only
parameter, and allows sending different TLS capability commands to the
server based on that greeting.

+++
** 'open-gnutls-stream' now also accepts a ':coding' argument.

+++
** New user option 'process-file-return-signal-string'.
It controls, whether 'process-file' returns a string when a remote
process is interrupted by a signal.

+++
** The behavior of 'format-spec' is now closer to that of 'format'.
In order for the two functions to behave more consistently,
'format-spec' now pads and truncates based on string width rather than
length, and also supports format specifications that include a
truncating precision field, such as "%.2a".

---
** New function 'color-values-from-color-spec'.
This can be used to parse RGB color specs in several formats and
convert them to a list '(R G B)' of primary color values.

\f
* Changes in Emacs 28.1 on Non-Free Operating Systems

---
** On macOS, Xwidget is now supported.
If Emacs was built with xwidget support, you can access the embedded
webkit browser with 'M-x xwidget-webkit-browse-url'.  Viewing two
instances of xwidget webkit is not supported.

*** Downloading files from xwidget-webkit is now supported.
The new variable 'xwidget-webkit-download-dir' says where to download to.

*** New functions for xwidget-webkit mode
'xwidget-webkit-clone-and-split-below',
'xwidget-webkit-clone-and-split-right'.

*** New variable 'xwidget-webkit-enable-plugins'.

+++
** On macOS, Emacs can now load dynamic modules with a ".dylib" suffix.
'module-file-suffix' now has the value ".dylib" on macOS, but the
".so" suffix is supported as well.

+++
** On MS-Windows, Emacs can now toggle the IME.
A new function 'w32-set-ime-open-status' can now be used to disable
and enable the MS-Windows native Input Method Editor (IME) at run
time.  A companion function 'w32-get-ime-open-status' returns the
current IME activation status.

+++
** On MS-Windows, Emacs can now use the native image API to display images.
Emacs can now use the MS-Windows GDI+ library to load and display
images in JPEG, PNG, GIF and TIFF formats.  This support is enabled
unless Emacs was configured '--without-native-image-api'.

This feature is experimental, and needs to be turned on to be used.
To turn this on, set the variable 'w32-use-native-image-API' to a
non-nil value.  Please report any bugs you find while using the native
image API via 'M-x report-emacs-bug'.

\f
----------------------------------------------------------------------
This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

\f
Local variables:
coding: utf-8
mode: outline
paragraph-separate: "[ 	\f]*$"
end: