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    1 GNU Emacs NEWS -- history of user-visible changes.
    2 
    3 Copyright (C) 2016-2018 Free Software Foundation, Inc.
    4 See the end of the file for license conditions.
    5 
    6 Please send Emacs bug reports to bug-gnu-emacs@gnu.org.
    7 If possible, use M-x report-emacs-bug.
    8 
    9 This file is about changes in Emacs version 26.
   10 
   11 See file HISTORY for a list of GNU Emacs versions and release dates.
   12 See files NEWS.25, NEWS.24, ..., NEWS.18, and NEWS.1-17 for changes
   13 in older Emacs versions.
   14 
   15 You can narrow news to a specific version by calling 'view-emacs-news'
   16 with a prefix argument or by typing C-u C-h C-n.
   17 
   18 
   19 * Installation Changes in Emacs 26.1
   20 
   21 ** By default libgnutls is now required when building Emacs.
   22 Use 'configure --with-gnutls=no' to build even when GnuTLS is missing.
   23 
   24 ** GnuTLS version 2.12.2 or later is now required, instead of merely
   25 version 2.6.6 or later.
   26 
   27 ** The new option 'configure --with-mailutils' causes Emacs to rely on
   28 GNU Mailutils to retrieve email.  It is recommended, and is the
   29 default if GNU Mailutils is installed.  When --with-mailutils is not
   30 in effect, the Emacs build procedure by default continues to build and
   31 install a limited 'movemail' substitute that retrieves POP3 email only
   32 via insecure channels.  To avoid this problem, use either
   33 --with-mailutils or --without-pop when configuring; --without-pop
   34 is the default on platforms other than native MS-Windows.
   35 
   36 ** The new option 'configure --enable-gcc-warnings=warn-only' causes
   37 GCC to issue warnings without stopping the build.  This behavior is
   38 now the default in developer builds.  As before, use
   39 '--disable-gcc-warnings' to suppress GCC's warnings, and
   40 '--enable-gcc-warnings' to stop the build if GCC issues warnings.
   41 
   42 ** When GCC warnings are enabled, '--enable-check-lisp-object-type' is
   43 now enabled by default when configuring.
   44 
   45 ** The Emacs server now has socket-launching support.  This allows
   46 socket based activation, where an external process like systemd can
   47 invoke the Emacs server process upon a socket connection event and
   48 hand the socket over to Emacs.  Emacs uses this socket to service
   49 emacsclient commands.  This new functionality can be disabled with the
   50 configure option '--disable-libsystemd'.
   51 
   52 ** A systemd user unit file is provided.  Use it in the standard way:
   53 'systemctl --user enable emacs'.
   54 (If your Emacs is installed in a non-standard location, you may
   55 need to copy the emacs.service file to eg ~/.config/systemd/user/)
   56 
   57 ** New configure option '--disable-build-details' attempts to build an
   58 Emacs that is more likely to be reproducible; that is, if you build
   59 and install Emacs twice, the second Emacs is a copy of the first.
   60 Deterministic builds omit the build date from the output of the
   61 'emacs-version' and 'erc-cmd-SV' functions, and the leave the
   62 following variables nil: 'emacs-build-system', 'emacs-build-time',
   63 'erc-emacs-build-time'.
   64 
   65 ** Emacs can now be built with support for Little CMS.
   66 
   67 If the lcms2 library is installed, Emacs will enable features built on
   68 top of that library.  The new configure option '--without-lcms2' can
   69 be used to build without lcms2 support even if it is installed.  Emacs
   70 linked to Little CMS exposes color management functions in Lisp: the
   71 color metrics 'lcms-cie-de2000' and 'lcms-cam02-ucs', as well as
   72 functions for conversion to and from CIE CAM02 and CAM02-UCS.
   73 
   74 ** The configure option '--with-gameuser' now defaults to 'no',
   75 as this appears to be the most common configuration in practice.
   76 When it is 'no', the shared game directory and the auxiliary program
   77 update-game-score are no longer needed and are not installed.
   78 
   79 ** Emacs no longer works on IRIX.  We expect that Emacs users are not
   80 affected by this, as SGI stopped supporting IRIX in December 2013.
   81 
   82 
   83 * Startup Changes in Emacs 26.1
   84 
   85 ** New option '--fg-daemon'.  This is the same as '--daemon', except
   86 it runs in the foreground and does not fork.  This is intended for
   87 modern init systems such as systemd, which manage many of the traditional
   88 aspects of daemon behavior themselves.  '--bg-daemon' is now an alias
   89 for '--daemon'.
   90 
   91 ** New option '--module-assertions'.
   92 When given this option, Emacs will perform expensive correctness
   93 checks when dealing with dynamic modules.  This is intended for module
   94 authors that wish to verify that their module conforms to the module
   95 requirements.  The option makes Emacs abort if a module-related
   96 assertion triggers.
   97 
   98 ** Emacs now supports 24-bit colors on capable text terminals.
   99 Terminal is automatically initialized to use 24-bit colors if the
  100 required capabilities are found in terminfo.  See the FAQ node
  101 "(efaq) Colors on a TTY" for more information.
  102 
  103 ** Emacs now obeys the X resource "scrollBar" at startup.
  104 The effect is similar to that of "toolBar" resource on the tool bar.
  105 
  106 
  107 * Changes in Emacs 26.1
  108 
  109 ** Option 'buffer-offer-save' can be set to new value, 'always'.  When
  110 set to 'always', the command 'save-some-buffers' will always offer
  111 this buffer for saving.
  112 
  113 ** Security vulnerability related to Enriched Text mode is removed.
  114 
  115 *** Enriched Text mode does not evaluate Lisp in 'display' properties.
  116 This feature allows saving 'display' properties as part of text.
  117 Emacs 'display' properties support evaluation of arbitrary Lisp forms
  118 as part of processing the property for display, so displaying Enriched
  119 Text could be vulnerable to executing arbitrary malicious Lisp code
  120 included in the text (e.g., sent as part of an email message).
  121 Therefore, execution of arbitrary Lisp forms in 'display' properties
  122 decoded by Enriched Text mode is now disabled by default.  Customize
  123 the new option 'enriched-allow-eval-in-display-props' to a non-nil
  124 value to allow Lisp evaluation in decoded 'display' properties.
  125 
  126 This vulnerability was introduced in Emacs 21.1.  To work around that
  127 in Emacs versions before 25.3, append the following to your ~/.emacs
  128 init file:
  129 
  130   (eval-after-load "enriched"
  131     '(defun enriched-decode-display-prop (start end &optional param)
  132        (list start end)))
  133 
  134 ** Functions in 'write-contents-functions' can fully short-circuit the
  135 'save-buffer' process.  Previously, saving a buffer that was not
  136 visiting a file would always prompt for a file name.  Now it only does
  137 so if 'write-contents-functions' is nil (or all its functions return
  138 nil).
  139 
  140 ** New variable 'executable-prefix-env' for inserting magic signatures.
  141 This variable affects the format of the interpreter magic number
  142 inserted by 'executable-set-magic'.  If non-nil, the magic number now
  143 takes the form "#!/usr/bin/env interpreter", otherwise the value
  144 determined by 'executable-prefix', which is by default
  145 "#!/path/to/interpreter".  By default, 'executable-prefix-env' is nil,
  146 so the default behavior is not changed.
  147 
  148 ** The variable 'emacs-version' no longer includes the build number.
  149 This is now stored separately in a new variable, 'emacs-build-number'.
  150 
  151 ** Emacs now provides a limited form of concurrency with Lisp threads.
  152 Concurrency in Emacs Lisp is "mostly cooperative", meaning that
  153 Emacs will only switch execution between threads at well-defined
  154 times: when Emacs waits for input, during blocking operations related
  155 to threads (such as mutex locking), or when the current thread
  156 explicitly yields.  Global variables are shared among all threads, but
  157 a 'let' binding is thread-local.  Each thread also has its own current
  158 buffer and its own match data.
  159 
  160 See the chapter "(elisp) Threads" in the ELisp manual for full
  161 documentation of these facilities.
  162 
  163 ** The new user variable 'electric-quote-chars' provides a list
  164 of curved quotes for 'electric-quote-mode', allowing user to choose
  165 the types of quotes to be used.
  166 
  167 ** The new user option 'electric-quote-context-sensitive' makes
  168 'electric-quote-mode' context sensitive.  If it is non-nil, you can
  169 type an ASCII apostrophe to insert an opening or closing quote,
  170 depending on context.  Emacs will replace the apostrophe by an opening
  171 quote character at the beginning of the buffer, the beginning of a
  172 line, after a whitespace character, and after an opening parenthesis;
  173 and it will replace the apostrophe by a closing quote character in all
  174 other cases.
  175 
  176 ** The new variable 'electric-quote-inhibit-functions' controls when
  177 to disable electric quoting based on context.  Major modes can add
  178 functions to this list; Emacs will temporarily disable
  179 'electric-quote-mode' whenever any of the functions returns non-nil.
  180 This can be used by major modes that derive from 'text-mode' but allow
  181 inline code segments, such as 'markdown-mode'.
  182 
  183 ** The new user variable 'dired-omit-case-fold' allows the user to
  184 customize the case-sensitivity of dired-omit-mode.  It defaults to
  185 the same sensitivity as that of the filesystem for the corresponding
  186 dired buffer.
  187 
  188 ** Emacs now uses double buffering to reduce flicker when editing and
  189 resizing graphical Emacs frames on the X Window System.  This support
  190 requires the DOUBLE-BUFFER extension, which major X servers have
  191 supported for many years.  If your system has this extension, but an
  192 Emacs built with double buffering misbehaves on some displays you use,
  193 you can disable the feature by adding
  194 
  195   '(inhibit-double-buffering . t)
  196 
  197 to default-frame-alist.  Or inject this parameter into the selected
  198 frame by evaluating this form:
  199 
  200   (modify-frame-parameters nil '((inhibit-double-buffering . t)))
  201 
  202 ** The customization group 'wp', whose label was "text", is now
  203 deprecated.  Use the new group 'text', which inherits from 'wp',
  204 instead.
  205 
  206 ** The new function 'call-shell-region' executes a command in an
  207 inferior shell with the buffer region as input.
  208 
  209 ** The new user option 'shell-command-dont-erase-buffer' controls
  210 if the output buffer is erased between shell commands; if non-nil,
  211 the output buffer is not erased; this variable also controls where
  212 to set the point in the output buffer: beginning of the output,
  213 end of the buffer or save the point.
  214 When 'shell-command-dont-erase-buffer' is nil, the default value,
  215 the behavior of 'shell-command', 'shell-command-on-region' and
  216 'async-shell-command' is as usual.
  217 
  218 ** The new user option 'async-shell-command-display-buffer' controls
  219 whether the output buffer of an asynchronous command is shown
  220 immediately, or only when there is output.
  221 
  222 ** New user option 'mouse-select-region-move-to-beginning'.
  223 This option controls the position of point when double-clicking
  224 mouse-1 on the end of a parenthetical grouping or string-delimiter:
  225 the default value nil keeps point at the end of the region, setting it
  226 to non-nil moves point to the beginning of the region.
  227 
  228 ** New user option 'mouse-drag-and-drop-region'.
  229 This option allows you to drag the entire region of text to another
  230 place or another buffer.  Its behavior is customizable via the new
  231 options 'mouse-drag-and-drop-region-cut-when-buffers-differ',
  232 'mouse-drag-and-drop-region-show-tooltip', and
  233 'mouse-drag-and-drop-region-show-cursor'.
  234 
  235 ** The new user option 'confirm-kill-processes' allows the user to
  236 skip a confirmation prompt for killing subprocesses when exiting
  237 Emacs.  When set to t (the default), Emacs will prompt for
  238 confirmation before killing subprocesses on exit, which is the same
  239 behavior as before.
  240 
  241 ** 'find-library-name' will now fall back on looking at 'load-history'
  242 to try to locate libraries that have been loaded with an explicit path
  243 outside 'load-path'.
  244 
  245 ** Faces in 'minibuffer-prompt-properties' no longer overwrite properties
  246 in the text in functions like 'read-from-minibuffer', but instead are
  247 added to the end of the face list.  This allows users to say things
  248 like '(read-from-minibuffer (propertize "Enter something: " 'face 'bold))'.
  249 
  250 ** The new variable 'extended-command-suggest-shorter' has been added
  251 to control whether to suggest shorter 'M-x' commands or not.
  252 
  253 ** icomplete now respects 'completion-ignored-extensions'.
  254 
  255 ** Non-breaking hyphens are now displayed with the 'nobreak-hyphen'
  256 face instead of the 'escape-glyph' face.
  257 
  258 ** Approximations to quotes are now displayed with the new 'homoglyph'
  259 face instead of the 'escape-glyph' face.
  260 
  261 ** New face 'header-line-highlight'.
  262 This face is the header-line analogue of 'mode-line-highlight'; it
  263 should be the preferred mouse-face for mouse-sensitive elements in the
  264 header line.
  265 
  266 ** 'C-x h' ('mark-whole-buffer') will now avoid marking the prompt
  267 part of minibuffers.
  268 
  269 ** 'fill-paragraph' no longer marks the buffer as changed unless it
  270 actually changed something.
  271 
  272 ** The locale language name 'ca' is now mapped to the language
  273 environment 'Catalan', which has been added.
  274 
  275 ** 'align-regexp' has a separate history for its interactive argument.
  276 'align-regexp' no longer shares its history with all other
  277 history-less functions that use 'read-string'.
  278 
  279 ** The networking code has been reworked so that it's more
  280 asynchronous than it was (when specifying :nowait t in
  281 'make-network-process').  How asynchronous it is varies based on the
  282 capabilities of the system, but on a typical GNU/Linux system the DNS
  283 resolution, the connection, and (for TLS streams) the TLS negotiation
  284 are all done without blocking the main Emacs thread.  To get
  285 asynchronous TLS, the TLS boot parameters have to be passed in (see
  286 the manual for details).
  287 
  288 Certain process oriented functions (like 'process-datagram-address')
  289 will block until socket setup has been performed.  The recommended way
  290 to deal with asynchronous sockets is to avoid interacting with them
  291 until they have changed status to "run".  This is most easily done
  292 from a process sentinel.
  293 
  294 ** 'make-network-process' and 'open-network-stream' sometimes allowed
  295 :service to be an integer string (e.g., :service "993") and sometimes
  296 required an integer (e.g., :service 993).  This difference has been
  297 eliminated, and integer strings work everywhere.
  298 
  299 ** It is possible to disable attempted recovery on fatal signals.
  300 Two new variables support disabling attempts to recover from stack
  301 overflow and to avoid automatic auto-save when Emacs is delivered a
  302 fatal signal.  'attempt-stack-overflow-recovery', if set to nil,
  303 will disable attempts to recover from C stack overflows; Emacs will
  304 then crash as with any other fatal signal.
  305 'attempt-orderly-shutdown-on-fatal-signal', if set to nil, will
  306 disable attempts to auto-save the session and shut down in an orderly
  307 fashion when Emacs receives a fatal signal; instead, Emacs will
  308 terminate immediately.  Both variables are non-nil by default.
  309 These variables are for users who would like to avoid the small
  310 probability of data corruption due to techniques Emacs uses to recover
  311 in these situations.
  312 
  313 ** File local and directory local variables are now initialized each
  314 time the major mode is set, not just when the file is first visited.
  315 These local variables will thus not vanish on setting a major mode.
  316 
  317 ** A second dir-local file (.dir-locals-2.el) is now accepted.
  318 See the doc string of 'dir-locals-file' for more information.
  319 
  320 ** Connection-local variables can be used to specify local variables
  321 with a value depending on the connected remote server.  For details,
  322 see the node "(elisp) Connection Local Variables" in the ELisp manual.
  323 
  324 ** International domain names (IDNA) are now encoded via the new
  325 puny.el library, so that one can visit Web sites with non-ASCII URLs.
  326 
  327 ** The new 'list-timers' command lists all active timers in a buffer,
  328 where you can cancel them with the 'c' command.
  329 
  330 ** 'switch-to-buffer-preserve-window-point' now defaults to t.
  331 Applications that call 'switch-to-buffer' and want to show the buffer at
  332 the position of its point should use 'pop-to-buffer-same-window' in lieu
  333 of 'switch-to-buffer'.
  334 
  335 ** The new variable 'debugger-stack-frame-as-list' allows displaying
  336 all call stack frames in a Lisp backtrace buffer as lists.  Both
  337 debug.el and edebug.el have been updated to heed to this variable.
  338 
  339 ** Values in call stack frames are now displayed using 'cl-prin1'.
  340 The old behavior of using 'prin1' can be restored by customizing the
  341 new option 'debugger-print-function'.
  342 
  343 ** NUL bytes in text copied to the system clipboard are now replaced with "\0".
  344 
  345 ** The new variable 'x-ctrl-keysym' has been added to the existing
  346 roster of X keysyms.  It can be used in combination with another
  347 variable of this kind to swap modifiers in Emacs.
  348 
  349 ** New input methods: 'cyrillic-tuvan', 'polish-prefix', 'uzbek-cyrillic'.
  350 
  351 ** The 'dutch' input method no longer attempts to support Turkish too.
  352 Also, it no longer converts 'IJ' and 'ij' to the compatibility
  353 characters U+0132 LATIN CAPITAL LIGATURE IJ and U+0133 LATIN SMALL
  354 LIGATURE IJ.
  355 
  356 ** File name quoting by adding the prefix "/:" is now possible for the
  357 local part of a remote file name.  Thus, if you have a directory named
  358 "/~" on the remote host "foo", you can prevent it from being
  359 substituted by a home directory by writing it as "/foo:/:/~/file".
  360 
  361 ** The new variable 'maximum-scroll-margin' allows having effective
  362 settings of 'scroll-margin' up to half the window size, instead of
  363 always restricting the margin to a quarter of the window.
  364 
  365 ** Emacs can scroll horizontally using mouse, touchpad, and trackbar.
  366 You can enable this by customizing 'mouse-wheel-tilt-scroll'.  If you
  367 want to reverse the direction of the scroll, customize
  368 'mouse-wheel-flip-direction'.
  369 
  370 ** The default GnuTLS priority string now includes %DUMBFW.
  371 This is to avoid bad behavior in some firewalls, which causes the
  372 connection to be closed by the remote host.
  373 
  374 ** Emacsclient changes
  375 
  376 *** Emacsclient has a new option '-u' / '--suppress-output'.
  377 This option suppresses display of return values from the server
  378 process.
  379 
  380 *** Emacsclient has a new option '-T' / '--tramp'.
  381 This helps with using a local Emacs session as the server for a remote
  382 emacsclient.  With appropriate setup, one can now set the EDITOR
  383 environment variable on a remote machine to emacsclient, and
  384 use the local Emacs to edit remote files via Tramp.  See the node
  385 "(emacs) emacsclient Options" in the user manual for the details.
  386 
  387 *** Emacsclient now accepts command-line options in ALTERNATE_EDITOR
  388 and '--alternate-editor'. For example, ALTERNATE_EDITOR="emacs -Q -nw".
  389 Arguments may be quoted "like this", so that for example an absolute
  390 path containing a space may be specified; quote escaping is not
  391 supported.
  392 
  393 ** New user option 'dig-program-options' and extended functionality
  394 for DNS-querying functions 'nslookup-host', 'dns-lookup-host',
  395 and 'run-dig'.  Each function now accepts an optional name server
  396 argument interactively (with a prefix argument) and non-interactively.
  397 
  398 ** 'describe-key-briefly' now ignores mouse movement events.
  399 
  400 ** The new variable 'eval-expression-print-maximum-character' prevents
  401 large integers from being displayed as characters by 'M-:' and similar
  402 commands.
  403 
  404 ** Two new commands for finding the source code of Emacs Lisp
  405 libraries: 'find-library-other-window' and 'find-library-other-frame'.
  406 
  407 ** The new variable 'display-raw-bytes-as-hex' allows you to change
  408 the display of raw bytes from octal to hex.
  409 
  410 ** You can now provide explicit field numbers in format specifiers.
  411 For example, '(format "%2$s %1$s %2$s" "X" "Y")' produces "Y X Y".
  412 
  413 ** Emacs now supports optional display of line numbers in the buffer.
  414 This is similar to what 'linum-mode' provides, but much faster and
  415 doesn't usurp the display margin for the line numbers.  Customize the
  416 buffer-local variable 'display-line-numbers' to activate this optional
  417 display.  Alternatively, you can use the 'display-line-numbers-mode'
  418 minor mode or the global 'global-display-line-numbers-mode'.  When
  419 using these modes, customize 'display-line-numbers-type' with the same
  420 value as you would use with 'display-line-numbers'.
  421 
  422 Line numbers are not displayed at all in minibuffer windows and in
  423 tooltips, as they are not useful there.
  424 
  425 Lisp programs can disable line-number display for a particular screen
  426 line by putting the 'display-line-numbers-disable' text property or
  427 overlay property on the first character of that screen line.  This is
  428 intended for add-on packages that need a finer control of the display.
  429 
  430 Lisp programs that need to know how much screen estate is used up for
  431 line-number display in a window can use the new function
  432 'line-number-display-width'.
  433 
  434 'linum-mode' and all similar packages are henceforth becoming obsolete.
  435 Users and developers are encouraged to switch to this new feature
  436 instead.
  437 
  438 ** The new user option 'arabic-shaper-ZWNJ-handling' controls how to
  439 handle ZWNJ in Arabic text rendering.
  440 
  441 
  442 * Editing Changes in Emacs 26.1
  443 
  444 ** New variable 'column-number-indicator-zero-based'.
  445 Traditionally, in Column Number mode, the displayed column number
  446 counts from zero starting at the left margin of the window.  This
  447 behavior is now controlled by 'column-number-indicator-zero-based'.
  448 If you would prefer for the displayed column number to count from one,
  449 you may set this variable to nil.  (Behind the scenes, there is now a
  450 new mode line construct, '%C', which operates exactly as '%c' does
  451 except that it counts from one.)
  452 
  453 ** New single-line horizontal scrolling mode.
  454 The 'auto-hscroll-mode' variable can now have a new special value,
  455 'current-line', which causes only the line where the cursor is
  456 displayed to be horizontally scrolled when lines are truncated on
  457 display and point moves outside the left or right window margin.
  458 
  459 ** New mode line constructs '%o' and '%q', and user option
  460 'mode-line-percent-position'.  '%o' displays the "degree of travel" of
  461 the window through the buffer.  Unlike the default '%p', this
  462 percentage approaches 100% as the window approaches the end of the
  463 buffer.  '%q' displays the percentage offsets of both the start and
  464 the end of the window, e.g. "5-17%".  The new option
  465 'mode-line-percent-position' makes it easier to switch between '%p',
  466 '%P', and these new constructs.
  467 
  468 ** Two new user options 'list-matching-lines-jump-to-current-line' and
  469 'list-matching-lines-current-line-face' to show the current line
  470 highlighted in *Occur* buffer.
  471 
  472 ** The 'occur' command can now operate on the region.
  473 
  474 ** New bindings for 'query-replace-map'.
  475 'undo', undo the last replacement; bound to 'u'.
  476 'undo-all', undo all replacements; bound to 'U'.
  477 
  478 ** 'delete-trailing-whitespace' deletes whitespace after form feed.
  479 In modes where form feed was treated as a whitespace character,
  480 'delete-trailing-whitespace' would keep lines containing it unchanged.
  481 It now deletes whitespace after the last form feed thus behaving the
  482 same as in modes where the character is not whitespace.
  483 
  484 ** Emacs no longer prompts about editing a changed file when the file's
  485 content is unchanged.  Instead of only checking the modification time,
  486 Emacs now also checks the file's actual content before prompting the user.
  487 
  488 ** Various casing improvements.
  489 
  490 *** 'upcase', 'upcase-region' et al. convert title case characters
  491 (such as Dz) into their upper case form (such as DZ).
  492 
  493 *** 'capitalize', 'upcase-initials' et al. make use of title-case forms
  494 of initial characters (correctly producing for example Džungla instead
  495 of incorrect DŽungla).
  496 
  497 *** Characters which turn into multiple ones when cased are correctly handled.
  498 For example, fi ligature is converted to FI when upper cased.
  499 
  500 *** Greek small sigma is correctly handled when at the end of the word.
  501 Strings such as ΌΣΟΣ are now correctly converted to Όσος when
  502 capitalized instead of incorrect Όσοσ (compare lowercase sigma at the
  503 end of the word).
  504 
  505 ** Emacs can now auto-save buffers to visited files in a more robust
  506 manner via the new mode 'auto-save-visited-mode'.  Unlike
  507 'auto-save-visited-file-name', this mode uses the normal saving
  508 procedure and therefore obeys saving hooks.
  509 'auto-save-visited-file-name' is now obsolete.
  510 
  511 ** New behavior of 'mark-defun'.
  512 Prefix argument selects that many (or that many more) defuns.
  513 Negative prefix arg flips the direction of selection.  Also,
  514 'mark-defun' between defuns correctly selects N following defuns (or
  515 -N previous for negative arguments).  Finally, comments preceding the
  516 defun are selected unless they are separated from the defun by a blank
  517 line.
  518 
  519 ** New command 'replace-buffer-contents'.
  520 This command replaces the contents of the accessible portion of the
  521 current buffer with the contents of the accessible portion of a
  522 different buffer while keeping point, mark, markers, and text
  523 properties as intact as possible.
  524 
  525 ** New commands 'apropos-local-variable' and 'apropos-local-value'.
  526 These are buffer-local versions of 'apropos-variable' and
  527 'apropos-value', respectively.  They show buffer-local variables whose
  528 names and values, respectively, match a given pattern.
  529 
  530 ** More user control of reordering bidirectional text for display.
  531 The two new variables, 'bidi-paragraph-start-re' and
  532 'bidi-paragraph-separate-re', allow customization of what exactly are
  533 paragraphs, for the purposes of bidirectional display.
  534 
  535 ** New variable 'x-wait-for-event-timeout'.
  536 This controls how long Emacs will wait for updates to the graphical
  537 state to take effect (making a frame visible, for example).
  538 
  539 
  540 * Changes in Specialized Modes and Packages in Emacs 26.1
  541 
  542 ** Emacs 26.1 comes with Org v9.1.6.
  543 See the file ORG-NEWS for user-visible changes in Org.
  544 
  545 ** New function 'cl-generic-p'.
  546 
  547 ** Dired
  548 
  549 *** You can answer 'all' in 'dired-do-delete' to delete recursively all
  550 remaining directories without more prompts.
  551 
  552 *** Dired supports wildcards in the directory part of the file names.
  553 
  554 *** You can now use '`?`' in 'dired-do-shell-command'.
  555 It gets replaced by the current file name, like ' ? '.
  556 
  557 *** A new option 'dired-always-read-filesystem' defaulting to nil.
  558 If non-nil, buffers visiting files are reverted before they are
  559 searched; for instance, in 'dired-mark-files-containing-regexp' a
  560 non-nil value of this option means the file is revisited in a
  561 temporary buffer; this temporary buffer is the actual buffer searched:
  562 the original buffer visiting the file is not modified.
  563 
  564 *** Users can now customize mouse clicks in Dired in a more flexible way.
  565 The new command 'dired-mouse-find-file' can be bound to a mouse click
  566 and used to visit files/directories in Dired in the selected window.
  567 The new command 'dired-mouse-find-file-other-frame' similarly visits
  568 files/directories in another frame.  You can write your own commands
  569 that invoke 'dired-mouse-find-file' with non-default optional
  570 arguments, to tailor the effects of mouse clicks on file names in
  571 Dired buffers.
  572 
  573 *** In wdired, when editing files to contain slash characters,
  574 the resulting directories are automatically created.  Whether to do
  575 this is controlled by the 'wdired-create-parent-directories' variable.
  576 
  577 *** 'W' is now bound to 'browse-url-of-dired-file', and is useful for
  578 viewing HTML files and the like.
  579 
  580 *** New variable 'dired-clean-confirm-killing-deleted-buffers'
  581 controls whether Dired asks to kill buffers visiting deleted files and
  582 directories.  The default is t, so Dired asks for confirmation, to
  583 keep previous behavior.
  584 
  585 ** html2text is now marked obsolete.
  586 
  587 ** smerge-refine-regions can refine regions in separate buffers.
  588 
  589 ** Info menu and index completion uses substring completion by default.
  590 This can be customized via the 'info-menu' category in
  591 'completion-category-overrides'.
  592 
  593 ** The ancestor buffer is shown by default in 3-way merges.
  594 A new option 'ediff-show-ancestor' and a new toggle
  595 'ediff-toggle-show-ancestor'.
  596 
  597 ** TeX: Add luatex and xetex as alternatives to pdftex
  598 
  599 ** Electric-Buffer-menu
  600 
  601 *** Key 'U' is bound to 'Buffer-menu-unmark-all' and key 'M-DEL' is
  602 bound to 'Buffer-menu-unmark-all-buffers'.
  603 
  604 ** hideshow mode got four key bindings that are analogous to outline
  605 mode bindings: 'C-c @ C-a', 'C-c @ C-t', 'C-c @ C-d', and 'C-c @ C-e'.
  606 
  607 ** bs
  608 
  609 *** Two new commands 'bs-unmark-all', bound to 'U', and
  610 'bs-unmark-previous', bound to <backspace>.
  611 
  612 ** Buffer-menu
  613 
  614 *** Two new commands 'Buffer-menu-unmark-all', bound to 'U' and
  615 'Buffer-menu-unmark-all-buffers', bound to 'M-DEL'.
  616 
  617 ** Checkdoc
  618 
  619 *** 'checkdoc-arguments-in-order-flag' now defaults to nil.
  620 
  621 ** Gnus
  622 
  623 *** The ~/.newsrc file will now only be saved if the native select
  624 method is an NNTP select method.
  625 
  626 *** A new command for sorting articles by readedness marks has been
  627 added: 'C-c C-s C-m C-m'.
  628 
  629 *** In 'message-citation-line-format' the '%Z' format is now the time
  630 zone name instead of the numeric form.  The '%z' format continues to
  631 be the numeric form.  The new behavior is compatible with
  632 'format-time-string'.
  633 
  634 ** Ibuffer
  635 
  636 *** New command 'ibuffer-jump'.
  637 
  638 *** New filter commands 'ibuffer-filter-by-basename',
  639 'ibuffer-filter-by-file-extension', 'ibuffer-filter-by-directory',
  640 'ibuffer-filter-by-starred-name', 'ibuffer-filter-by-modified'
  641 and 'ibuffer-filter-by-visiting-file'; bound respectively
  642 to '/b', '/.', '//', '/*', '/i' and '/v'.
  643 
  644 *** Two new commands 'ibuffer-filter-chosen-by-completion'
  645 and 'ibuffer-and-filter', the second bound to '/&'.
  646 
  647 *** The commands 'ibuffer-pop-filter', 'ibuffer-pop-filter-group',
  648 'ibuffer-or-filter' and 'ibuffer-filter-disable' have the alternative
  649 bindings '/<up>', '/S-<up>', '/|' and '/DEL', respectively.
  650 
  651 *** The data format specifying filters has been extended to allow
  652 explicit logical 'and', and a more flexible form for logical 'not'.
  653 See 'ibuffer-filtering-qualifiers' doc string for full details.
  654 
  655 *** A new command 'ibuffer-copy-buffername-as-kill'; bound
  656 to 'B'.
  657 
  658 *** New command 'ibuffer-change-marks'; bound to '* c'.
  659 
  660 *** A new command 'ibuffer-mark-by-locked' to mark
  661 all locked buffers;  bound to '% L'.
  662 
  663 *** A new option 'ibuffer-locked-char' to indicate
  664 locked buffers; Ibuffer shows a new column displaying
  665 'ibuffer-locked-char' for locked buffers.
  666 
  667 *** A new command 'ibuffer-unmark-all-marks' to unmark
  668 all buffers without asking confirmation;  bound to
  669 'U'; 'ibuffer-do-replace-regexp' bound to 'r'.
  670 
  671 *** A new command 'ibuffer-mark-by-content-regexp' to mark buffers
  672 whose content matches a regexp; bound to '% g'.
  673 
  674 *** Two new options 'ibuffer-never-search-content-name' and
  675 'ibuffer-never-search-content-mode' used by
  676 'ibuffer-mark-by-content-regexp'.
  677 
  678 ** Browse-URL
  679 
  680 *** Support for opening links to man pages in Man or WoMan mode.
  681 
  682 ** Comint
  683 
  684 *** New user option 'comint-move-point-for-matching-input' to control
  685 where to place point after 'C-c M-r' and 'C-c M-s'.
  686 
  687 *** New user option 'comint-terminfo-terminal'.
  688 This option allows control of the value of the TERM environment
  689 variable Emacs puts into the environment of the Comint mode and its
  690 derivatives, such as Shell mode and Compilation Shell minor-mode.  The
  691 default is "dumb", for compatibility with previous behavior.
  692 
  693 ** Compilation mode
  694 
  695 *** Messages from CMake are now recognized.
  696 
  697 *** The number of errors, warnings, and informational messages is now
  698 displayed in the mode line.  These are updated as compilation
  699 proceeds.
  700 
  701 ** Grep
  702 
  703 *** Grep commands will now use GNU grep's '--null' option if
  704 available, which allows distinguishing the filename from contents if
  705 they contain colons.  This can be controlled by the new custom option
  706 'grep-use-null-filename-separator'.
  707 
  708 *** The grep/rgrep/lgrep functions will now ask about saving files
  709 before running.  This is controlled by the 'grep-save-buffers'
  710 variable.
  711 
  712 ** Edebug
  713 
  714 *** Edebug can be prevented from pausing 1 second after reaching a
  715 breakpoint (e.g. with "f" and "o") by customizing the new option
  716 'edebug-sit-on-break'.
  717 
  718 *** New customizable option 'edebug-max-depth'.
  719 This allows you to enlarge the maximum recursion depth when
  720 instrumenting code.
  721 
  722 *** 'edebug-prin1-to-string' now aliases 'cl-prin1-to-string'.
  723 This means edebug output is affected by variables 'cl-print-readably'
  724 and 'cl-print-compiled'.  To completely restore the previous printing
  725 behavior, use
  726 
  727     (fset 'edebug-prin1-to-string #'prin1-to-string)
  728 
  729 ** Eshell
  730 
  731 *** 'eshell-input-filter's value is now a named function
  732 'eshell-input-filter-default', and has a new custom option
  733 'eshell-input-filter-initial-space' to ignore adding commands prefixed
  734 with blank space to eshell history.
  735 
  736 ** EUDC
  737 
  738 *** Backward compatibility support for BBDB versions less than 3
  739 (i.e., BBDB 2.x) is deprecated and will likely be removed in the next
  740 major release of Emacs.  Users of BBDB 2.x should plan to upgrade to
  741 BBDB 3.x.
  742 
  743 ** eww
  744 
  745 *** New 'M-RET' command for opening a link at point in a new eww buffer.
  746 
  747 *** A new 's' command for switching to another eww buffer via the minibuffer.
  748 
  749 *** The 'o' command ('shr-save-contents') has moved to 'O' to avoid collision
  750 with the 'o' command from 'image-map'.
  751 
  752 *** A new command 'C' ('eww-toggle-colors') can be used to toggle
  753 whether to use the HTML-specified colors or not.  The user can also
  754 customize the 'shr-use-colors' variable.
  755 
  756 *** Images that are being loaded are now marked with gray
  757 "placeholder" images of the size specified by the HTML.  They are then
  758 replaced by the real images asynchronously, which will also now
  759 respect width/height HTML specs (unless they specify widths/heights
  760 bigger than the current window).
  761 
  762 *** The 'w' command on links is now 'shr-maybe-probe-and-copy-url'.
  763 'shr-copy-url' now only copies the url at point; users who wish to
  764 avoid accidentally accessing remote links may rebind 'w' and 'u' in
  765 'eww-link-keymap' to it.
  766 
  767 ** Ido
  768 
  769 *** The commands 'find-alternate-file-other-window',
  770 'dired-other-window', 'dired-other-frame', and
  771 'display-buffer-other-window' are now remapped to Ido equivalents if
  772 Ido mode is active.
  773 
  774 ** Images
  775 
  776 *** Images are automatically scaled before displaying based on the
  777 'image-scaling-factor' variable (if Emacs supports scaling the images
  778 in question).
  779 
  780 *** It's now possible to specify aspect-ratio preserving combinations
  781 of :width/:max-height and :height/:max-width keywords.  In either
  782 case, the "max" keywords win.  (Previously some combinations would,
  783 depending on the aspect ratio of the image, just be ignored and in
  784 other instances this would lead to the aspect ratio not being
  785 preserved.)
  786 
  787 *** Images inserted with 'insert-image' and related functions get a
  788 keymap put into the text properties (or overlays) that span the
  789 image.  This keymap binds keystrokes for manipulating size and
  790 rotation, as well as saving the image to a file.  These commands are
  791 also available in 'image-mode'.
  792 
  793 *** A new library for creating and manipulating SVG images has been
  794 added.  See the "(elisp) SVG Images" section in the ELisp reference
  795 manual for details.
  796 
  797 *** New setf-able function to access and set image parameters is
  798 provided: 'image-property'.
  799 
  800 *** New commands 'image-scroll-left' and 'image-scroll-right'
  801 for 'image-mode' that complement 'image-scroll-up' and
  802 'image-scroll-down': they have the same prefix arg behavior and stop
  803 at image boundaries.
  804 
  805 ** Image-Dired
  806 
  807 *** Now provides a minor mode 'image-dired-minor-mode' which replaces
  808 the function 'image-dired-setup-dired-keybindings'.
  809 
  810 *** Thumbnail generation is now asynchronous.
  811 The number of concurrent processes is limited by the variable
  812 'image-dired-queue-active-limit'.
  813 
  814 *** 'image-dired-thumbnail-storage' has a new option 'standard-large'
  815 for generating 256x256 thumbnails according to the Thumbnail Managing
  816 Standard.
  817 
  818 *** Inherits movement keys from 'image-mode' for viewing full images.
  819 This includes the usual char, line, and page movement commands.
  820 
  821 *** All the -options types have been changed to argument lists
  822 instead of shell command strings.  This change affects
  823 'image-dired-cmd-create-thumbnail-options',
  824 'image-dired-cmd-create-temp-image-options',
  825 'image-dired-cmd-rotate-thumbnail-options',
  826 'image-dired-cmd-rotate-original-options',
  827 'image-dired-cmd-write-exif-data-options',
  828 'image-dired-cmd-read-exif-data-options', and introduces
  829 'image-dired-cmd-pngnq-options', 'image-dired-cmd-pngcrush-options',
  830 'image-dired-cmd-create-standard-thumbnail-options'.
  831 
  832 *** Recognizes more tools by default, including pngnq-s9 and OptiPNG.
  833 
  834 *** 'find-file' and related commands now work on thumbnails and
  835 displayed images, providing a default argument of the original file name
  836 via an addition to 'file-name-at-point-functions'.
  837 
  838 ** The default 'Info-default-directory-list' no longer checks some obsolete
  839 directory suffixes (gnu, gnu/lib, gnu/lib/emacs, emacs, lib, lib/emacs)
  840 when searching for info directories.
  841 
  842 ** The commands that add ChangeLog entries now prefer a VCS root directory
  843 for the ChangeLog file, if none already exists.  Customize
  844 'change-log-directory-files' to nil for the old behavior.
  845 
  846 ** Support for non-string values of 'time-stamp-format' has been removed.
  847 
  848 ** Message
  849 
  850 *** 'message-use-idna' now defaults to t (because Emacs comes with
  851 built-in IDNA support now).
  852 
  853 *** When sending HTML messages with embedded images, and you have
  854 exiftool installed, and you rotate images with EXIF data (i.e.,
  855 JPEGs), the rotational information will be inserted into the outgoing
  856 image in the message.  (The original image will not have its
  857 orientation affected.)
  858 
  859 *** The 'message-valid-fqdn-regexp' variable has been removed, since
  860 there are now top-level domains added all the time.  Message will no
  861 longer warn about sending emails to top-level domains it hasn't heard
  862 about.
  863 
  864 *** 'message-beginning-of-line' (bound to 'C-a') understands folded headers.
  865 In 'visual-line-mode' it will look for the true beginning of a header
  866 while in non-'visual-line-mode' it will move the point to the indented
  867 header's value.
  868 
  869 ** Package
  870 
  871 *** The new variable 'package-gnupghome-dir' has been added to control
  872 where the GnuPG home directory (used for signature verification) is
  873 located and whether GnuPG's option '--homedir' is used or not.
  874 
  875 *** Deleting a package no longer respects 'delete-by-moving-to-trash'.
  876 
  877 ** Python
  878 
  879 *** The new variable 'python-indent-def-block-scale' has been added.
  880 It controls the depth of indentation of arguments inside multi-line
  881 function signatures.
  882 
  883 ** Tramp
  884 
  885 *** The method part of remote file names is mandatory now.
  886 A valid remote file name starts with "/method:host:" or
  887 "/method:user@host:".
  888 
  889 *** The new pseudo method "-" is a marker for the default method.
  890 "/-::" is the shortest remote file name then.
  891 
  892 *** The command 'tramp-change-syntax' allows you to choose an
  893 alternative remote file name syntax.
  894 
  895 *** New connection method "sg", which supports editing files under a
  896 different group ID.
  897 
  898 *** New connection method "doas" for OpenBSD hosts.
  899 
  900 *** New connection method "gdrive", which allows access to Google
  901 Drive onsite repositories.
  902 
  903 *** Gateway methods in Tramp have been removed.
  904 Instead, the Tramp manual documents how to configure ssh and PuTTY
  905 accordingly.
  906 
  907 *** Setting the "ENV" environment variable in
  908 'tramp-remote-process-environment' enables reading of shell
  909 initialization files.
  910 
  911 *** Tramp is able now to send SIGINT to remote asynchronous processes.
  912 
  913 *** Variable 'tramp-completion-mode' is obsoleted.
  914 
  915 ** 'auto-revert-use-notify' is set back to t in 'global-auto-revert-mode'.
  916 
  917 ** JS mode
  918 
  919 *** JS mode now sets 'comment-multi-line' to t.
  920 
  921 *** New variable 'js-indent-align-list-continuation', when set to nil,
  922 will not align continuations of bracketed lists, but will indent them
  923 by the fixed width 'js-indent-level'.
  924 
  925 ** CSS mode
  926 
  927 *** Support for completing attribute values, at-rules, bang-rules,
  928 HTML tags, classes and IDs using the 'completion-at-point' command.
  929 Completion candidates for HTML classes and IDs are retrieved from open
  930 HTML mode buffers.
  931 
  932 *** CSS mode now binds 'C-h S' to a function that will show
  933 information about a CSS construct (an at-rule, property, pseudo-class,
  934 pseudo-element, with the default being guessed from context).  By
  935 default the information is looked up on the Mozilla Developer Network,
  936 but this can be customized using 'css-lookup-url-format'.
  937 
  938 *** CSS colors are fontified using the color they represent as the
  939 background.  For instance, #ff0000 would be fontified with a red
  940 background.
  941 
  942 ** Emacs now supports character name escape sequences in character and
  943 string literals.  The syntax variants '\N{character name}' and
  944 '\N{U+code}' are supported.
  945 
  946 ** Prog mode has some support for multi-mode indentation.
  947 This allows better indentation support in modes that support multiple
  948 programming languages in the same buffer, like literate programming
  949 environments or ANTLR programs with embedded Python code.
  950 
  951 A major mode can provide indentation context for a sub-mode.  To
  952 support this, modes should use 'prog-first-column' instead of a
  953 literal zero and avoid calling 'widen' in their indentation functions.
  954 See the node "(elisp) Mode-Specific Indent" in the ELisp manual for
  955 more details.
  956 
  957 ** ERC
  958 
  959 *** New variable 'erc-default-port-tls' used to connect to TLS IRC
  960 servers.
  961 
  962 ** URL
  963 
  964 *** The new function 'url-cookie-delete-cookie' can be used to
  965 programmatically delete all cookies, or cookies from a specific
  966 domain.
  967 
  968 *** 'url-retrieve-synchronously' now takes an optional timeout parameter.
  969 
  970 *** The URL package now supports HTTPS over proxies supporting CONNECT.
  971 
  972 *** 'url-user-agent' now defaults to 'default', and the User-Agent
  973 string is computed dynamically based on 'url-privacy-level'.
  974 
  975 ** VC and related modes
  976 
  977 *** 'vc-dir-mode' now binds 'vc-log-outgoing' to 'O'; and has various
  978 branch-related commands on a keymap bound to 'B'.
  979 
  980 *** 'vc-region-history' is now bound to 'C-x v h', replacing the older
  981 'vc-insert-headers' binding.
  982 
  983 *** New user option 'vc-git-print-log-follow' to follow renames in Git logs
  984 for a single file.
  985 
  986 ** CC mode
  987 
  988 *** Opening a .h file will turn C or C++ mode depending on language used.
  989 This is done with the help of the 'c-or-c++-mode' function, which
  990 analyzes buffer contents to infer whether it's a C or C++ source file.
  991 
  992 ** New option 'cpp-message-min-time-interval' to allow user control
  993 of progress messages in cpp.el.
  994 
  995 ** New DNS mode command 'dns-mode-ipv6-to-nibbles' to convert IPv6 addresses
  996 to a format suitable for reverse lookup zone files.
  997 
  998 ** Ispell
  999 
 1000 *** Enchant is now supported as a spell-checker.
 1001 
 1002 Enchant is a meta-spell-checker that uses providers such as Hunspell
 1003 to do the actual checking.  With it, users can use spell-checkers not
 1004 directly supported by Emacs, such as Voikko, Hspell and AppleSpell,
 1005 more easily share personal word-lists with other programs, and
 1006 configure different spelling-checkers for different languages.
 1007 (Version 2.1.0 or later of Enchant is required.)
 1008 
 1009 ** Flymake
 1010 
 1011 *** Flymake has been completely redesigned
 1012 
 1013 Flymake now annotates arbitrary buffer regions, not just lines.  It
 1014 supports arbitrary diagnostic types, not just errors and warnings (see
 1015 variable 'flymake-diagnostic-types-alist').
 1016 
 1017 It also supports multiple simultaneous backends, meaning that you can
 1018 check your buffer from different perspectives (see variable
 1019 'flymake-diagnostic-functions').  Backends for Emacs Lisp mode are
 1020 provided.
 1021 
 1022 The old Flymake behavior is preserved in the so-called "legacy
 1023 backend", which has been updated to benefit from the new UI features.
 1024 
 1025 ** Term
 1026 
 1027 *** 'term-char-mode' now makes its buffer read-only.
 1028 
 1029 The buffer is made read-only to prevent changes from being made by
 1030 anything other than the process filter; and movements of point away
 1031 from the process mark are counter-acted so that the cursor is in the
 1032 correct position after each command.  This is needed to avoid states
 1033 which are inconsistent with the state of the terminal understood by
 1034 the inferior process.
 1035 
 1036 New user options 'term-char-mode-buffer-read-only' and
 1037 'term-char-mode-point-at-process-mark' control these behaviors, and
 1038 are non-nil by default.  Customize these options to nil if you want
 1039 the previous behavior.
 1040 
 1041 ** Xref
 1042 
 1043 *** When an *xref* buffer is needed, 'TAB' quits and jumps to an xref.
 1044 
 1045 A new command 'xref-quit-and-goto-xref', bound to 'TAB' in *xref*
 1046 buffers, quits the window before jumping to the destination.  In many
 1047 situations, the intended window configuration is restored, just as if
 1048 the *xref* buffer hadn't been necessary in the first place.
 1049 
 1050 
 1051 * New Modes and Packages in Emacs 26.1
 1052 
 1053 ** New Elisp data-structure library 'radix-tree'.
 1054 
 1055 ** New library 'xdg' with utilities for some XDG standards and specs.
 1056 
 1057 ** HTML
 1058 
 1059 *** A new submode of 'html-mode', 'mhtml-mode', is now the default
 1060 mode for *.html files.  This mode handles indentation,
 1061 fontification, and commenting for embedded JavaScript and CSS.
 1062 
 1063 ** New mode 'conf-toml-mode' is a sub-mode of 'conf-mode', specialized
 1064 for editing TOML files.
 1065 
 1066 ** New mode 'conf-desktop-mode' is a sub-mode of 'conf-unix-mode',
 1067 specialized for editing freedesktop.org desktop entries.
 1068 
 1069 ** New minor mode 'pixel-scroll-mode' provides smooth pixel-level scrolling.
 1070 
 1071 ** New major mode 'less-css-mode' (a minor variant of 'css-mode') for
 1072 editing Less files.
 1073 
 1074 ** New package 'auth-source-pass' integrates 'auth-source' with the
 1075 password manager password-store (http://passwordstore.org).
 1076 
 1077 
 1078 * Incompatible Lisp Changes in Emacs 26.1
 1079 
 1080 ** 'password-data' is now a hash-table so that 'password-read' can use
 1081 any object for the 'key' argument.
 1082 
 1083 ** Command 'dired-mark-extension' now automatically prepends a '.' to the
 1084 extension when not present.  The new command 'dired-mark-suffix' behaves
 1085 similarly but it doesn't prepend a '.'.
 1086 
 1087 ** Certain cond/pcase/cl-case forms are now compiled using a faster jump
 1088 table implementation.  This uses a new bytecode op 'switch', which
 1089 isn't compatible with previous Emacs versions.  This functionality can
 1090 be disabled by setting 'byte-compile-cond-use-jump-table' to nil.
 1091 
 1092 ** If 'comment-auto-fill-only-comments' is non-nil, 'auto-fill-function'
 1093 is now called only if either no comment syntax is defined for the
 1094 current buffer or the self-insertion takes place within a comment.
 1095 
 1096 ** The alist 'ucs-names' is now a hash table.
 1097 
 1098 ** 'if-let' and 'when-let' now support binding lists as defined by the
 1099 SRFI-2 (Scheme Request for Implementation 2).
 1100 
 1101 ** 'C-up', 'C-down', 'C-left' and 'C-right' are now defined in term
 1102 mode to send the same escape sequences that xterm does.  This makes
 1103 things like 'forward-word' in readline work.
 1104 
 1105 ** Customizable variable 'query-replace-from-to-separator'
 1106 now doesn't propertize the string value of the separator.
 1107 Instead, text properties are added by 'query-replace-read-from'.
 1108 Additionally, the new nil value restores pre-24.5 behavior
 1109 of not providing replacement pairs via the history.
 1110 
 1111 ** Some obsolete functions, variables, and faces have been removed:
 1112 
 1113 *** 'make-variable-frame-local'.  Variables cannot be frame-local any more.
 1114 
 1115 *** From subr.el: 'window-dot', 'set-window-dot', 'read-input',
 1116 'show-buffer', 'eval-current-buffer', 'string-to-int'.
 1117 
 1118 *** 'icomplete-prospects-length'.
 1119 
 1120 *** All the default-FOO variables that hold the default value of the
 1121 FOO variable.  Use 'default-value' and 'setq-default' to access and
 1122 change FOO, respectively.  The exhaustive list of removed variables is:
 1123 'default-mode-line-format', 'default-header-line-format',
 1124 'default-line-spacing', 'default-abbrev-mode', 'default-ctl-arrow',
 1125 'default-truncate-lines', 'default-left-margin', 'default-tab-width',
 1126 'default-case-fold-search', 'default-left-margin-width',
 1127 'default-right-margin-width', 'default-left-fringe-width',
 1128 'default-right-fringe-width', 'default-fringes-outside-margins',
 1129 'default-scroll-bar-width', 'default-vertical-scroll-bar',
 1130 'default-indicate-empty-lines', 'default-indicate-buffer-boundaries',
 1131 'default-fringe-indicator-alist', 'default-fringe-cursor-alist',
 1132 'default-scroll-up-aggressively', 'default-scroll-down-aggressively',
 1133 'default-fill-column', 'default-cursor-type',
 1134 'default-cursor-in-non-selected-windows',
 1135 'default-buffer-file-coding-system', 'default-major-mode', and
 1136 'default-enable-multibyte-characters'.
 1137 
 1138 *** Many variables obsoleted in 22.1 referring to face symbols.
 1139 
 1140 ** The variable 'text-quoting-style' is now a customizable option.  It
 1141 controls whether to and how to translate ASCII quotes in messages and
 1142 help output.  Its possible values and their semantics remain unchanged
 1143 from Emacs 25.  In particular, when this variable's value is 'grave',
 1144 all quotes in formats are output as-is.
 1145 
 1146 ** Functions like 'check-declare-file' and 'check-declare-directory'
 1147 now generate less chatter and more-compact diagnostics.  The auxiliary
 1148 function 'check-declare-errmsg' has been removed.
 1149 
 1150 ** The regular expression character class '[:blank:]' now matches
 1151 Unicode horizontal whitespace as defined in the Unicode Technical
 1152 Standard #18.  If you only want to match space and tab, use '[ \t]'
 1153 instead.
 1154 
 1155 ** 'min' and 'max' no longer round their results.
 1156 Formerly, they returned a floating-point value if any argument was
 1157 floating-point, which was sometimes numerically incorrect.  For
 1158 example, on a 64-bit host (max 1e16 10000000000000001) now returns its
 1159 second argument instead of its first.
 1160 
 1161 ** The variable 'old-style-backquotes' has been made internal and
 1162 renamed to 'lread--old-style-backquotes'.  No user code should use
 1163 this variable.
 1164 
 1165 ** 'default-file-name-coding-system' now defaults to a coding system
 1166 that does not process CRLF.  For example, it defaults to 'utf-8-unix'
 1167 instead of to 'utf-8'.  Before this change, Emacs would sometimes
 1168 mishandle file names containing these control characters.
 1169 
 1170 ** 'file-attributes', 'file-symlink-p' and 'make-symbolic-link' no
 1171 longer quietly mutate the target of a local symbolic link, so that
 1172 Emacs can access and copy them reliably regardless of their contents.
 1173 The following changes are involved.
 1174 
 1175 *** 'file-attributes' and 'file-symlink-p' no longer prepend "/:" to
 1176 symbolic links whose targets begin with "/" and contain ":".  For
 1177 example, if a symbolic link "x" has a target "/y:z:", '(file-symlink-p
 1178 "x")' now returns "/y:z:" rather than "/:/y:z:".
 1179 
 1180 *** 'make-symbolic-link' no longer looks for file name handlers of
 1181 target when creating a symbolic link.  For example,
 1182 '(make-symbolic-link "/y:z:" "x")' now creates a symbolic link to
 1183 "/y:z:" instead of failing.
 1184 
 1185 *** 'make-symbolic-link' removes the remote part of a link target if
 1186 target and newname have the same remote part.  For example,
 1187 '(make-symbolic-link "/x:y:a" "/x:y:b")' creates a link with the
 1188 literal string "a"; and '(make-symbolic-link "/x:y:a" "/x:z:b")'
 1189 creates a link with the literal string "/x:y:a" instead of failing.
 1190 
 1191 *** 'make-symbolic-link' now expands a link target with leading "~"
 1192 only when the optional third arg is an integer, as when invoked
 1193 interactively.  For example, '(make-symbolic-link "~y" "x")' now
 1194 creates a link with target the literal string "~y"; to get the old
 1195 behavior, use '(make-symbolic-link (expand-file-name "~y") "x")'.  To
 1196 avoid this expansion in interactive use, you can now prefix the link
 1197 target with "/:".  For example, '(make-symbolic-link "/:~y" "x" 1)'
 1198 now creates a link to literal "~y".
 1199 
 1200 ** 'file-truename' returns a quoted file name if the target of a
 1201 symbolic link has remote file name syntax.
 1202 
 1203 ** Module functions are now implemented slightly differently; in
 1204 particular, the function 'internal--module-call' has been removed.
 1205 Code that depends on undocumented internals of the module system might
 1206 break.
 1207 
 1208 ** The argument LOCKNAME of 'write-region' is propagated to file name
 1209 handlers now.
 1210 
 1211 ** When built against recent versions of GTK+, Emacs always uses
 1212 gtk_window_move for moving frames and ignores the value of the
 1213 variable 'x-gtk-use-window-move'.  The variable is now obsolete.
 1214 
 1215 ** Several functions that create or rename files now treat their
 1216 destination argument specially only when it is a directory name, i.e.,
 1217 when it ends in '/' on GNU and other POSIX-like systems.  When the
 1218 destination argument D of one of these functions is an existing
 1219 directory and the intent is to act on an entry in that directory, D
 1220 should now be a directory name.  For example, (rename-file "e" "f/")
 1221 renames to 'f/e'.  Although this formerly happened sometimes even when
 1222 D was not a directory name, as in (rename-file "e" "f") where 'f'
 1223 happened to be a directory, the old behavior often contradicted the
 1224 documentation and had inherent races that led to security holes.  A
 1225 call like (rename-file C D) that used the old, undocumented behavior
 1226 can be written as (rename-file C (file-name-as-directory D)), a
 1227 formulation portable to both older and newer versions of Emacs.
 1228 Affected functions include 'add-name-to-file', 'copy-directory',
 1229 'copy-file', 'format-write-file', 'gnus-copy-file',
 1230 'make-symbolic-link', 'rename-file', 'thumbs-rename-images', and
 1231 'write-file'.
 1232 
 1233 ** The list returned by 'overlays-at' is now in decreasing priority order.
 1234 The documentation of this function always said the order should be
 1235 that of decreasing priority, if the 2nd argument of the function is
 1236 non-nil, but the code returned the list in the increasing order of
 1237 priority instead.  Now the code does what the documentation says it
 1238 should do.
 1239 
 1240 ** 'format' now avoids allocating a new string in more cases.
 1241 'format' was previously documented to return a newly-allocated string,
 1242 but this documentation was not correct, as (eq x (format x)) returned
 1243 t when x was the empty string.  'format' is no longer documented to
 1244 return a newly-allocated string, and the implementation now takes
 1245 advantage of the doc change to avoid making copies of strings in
 1246 common cases like (format "foo") and (format "%s" "foo").
 1247 
 1248 ** The function 'eldoc-message' now accepts a single argument.
 1249 Programs that called it with multiple arguments before should pass
 1250 them through 'format' first.  Even that is discouraged: for ElDoc
 1251 support, you should set 'eldoc-documentation-function' instead of
 1252 calling 'eldoc-message' directly.
 1253 
 1254 ** Using '&rest' or '&optional' incorrectly is now an error.
 1255 For example giving '&optional' without a following variable, or
 1256 passing '&optional' multiple times:
 1257 
 1258     (defun foo (&optional &rest x))
 1259     (defun bar (&optional &optional x))
 1260 
 1261 Previously, Emacs would just ignore the extra keyword, or give
 1262 incorrect results in certain cases.
 1263 
 1264 ** The pinentry.el library has been removed.
 1265 That package (and the corresponding change in GnuPG and pinentry)
 1266 was intended to provide a way to input passphrase through Emacs with
 1267 GnuPG 2.0.  However, the change to support that was only implemented
 1268 in GnuPG >= 2.1 and didn't get backported to GnuPG 2.0.  And with
 1269 GnuPG 2.1 and later, pinentry.el is not needed at all.  So the
 1270 library was useless, and we removed it.  GnuPG 2.0 is no longer
 1271 supported by the upstream project.
 1272 
 1273 To adapt to the change, you may need to set 'epa-pinentry-mode' to the
 1274 symbol 'loopback'.  Alternatively, leave 'epa-pinentry-mode' at its
 1275 default value of nil, and remove the 'allow-emacs-pinentry' setting
 1276 from your 'gpg-agent.conf' configuration file, usually found in the
 1277 '~/.gnupg' directory.
 1278 
 1279 Note that previously, it was said that passphrase input through
 1280 minibuffer would be much less secure than other graphical pinentry
 1281 programs.  However, these days the difference is insignificant: the
 1282 'read-password' function sufficiently protects input from leakage to
 1283 message logs.  Emacs still doesn't use secure memory to protect
 1284 passphrases, but it was also removed from other pinentry programs as
 1285 the attack is unrealistic on modern computer systems which don't
 1286 utilize swap memory usually.
 1287 
 1288 ** The function 'display-buffer-in-major-side-window' no longer exists.
 1289 It has been renamed as internal function 'window--make-major-side-window',
 1290 however applications should instead call 'display-buffer-in-side-window'
 1291 (passing the SIDE and SLOT parameters as elements of ALIST).  This approach
 1292 is backwards-compatible with versions of Emacs in which the old function
 1293 exists.  See the node "Displaying Buffers in Side Windows" in the ELisp
 1294 manual for more details.
 1295 
 1296 * Lisp Changes in Emacs 26.1
 1297 
 1298 ** The function 'assoc' now takes an optional third argument TESTFN.
 1299 This argument, when non-nil, is used for comparison instead of
 1300 'equal'.
 1301 
 1302 ** New optional argument TESTFN in 'alist-get', 'map-elt' and 'map-put'.
 1303 If non-nil, the argument specifies a function to use for comparison,
 1304 instead of, respectively, 'assq' and 'eql'.
 1305 
 1306 ** New function 'seq-set-equal-p' to check if SEQUENCE1 and SEQUENCE2
 1307 contain the same elements, regardless of the order.
 1308 
 1309 ** The new function 'mapbacktrace' applies a function to all frames of
 1310 the current stack trace.
 1311 
 1312 ** The new function 'file-name-case-insensitive-p' tests whether a
 1313 given file is on a case-insensitive filesystem.
 1314 
 1315 ** Several accessors for the value returned by 'file-attributes'
 1316 have been added.  They are: 'file-attribute-type',
 1317 'file-attribute-link-number', 'file-attribute-user-id',
 1318 'file-attribute-group-id', 'file-attribute-access-time',
 1319 'file-attribute-modification-time',
 1320 'file-attribute-status-change-time', 'file-attribute-size',
 1321 'file-attribute-modes', 'file-attribute-inode-number',
 1322 'file-attribute-device-number' and 'file-attribute-collect'.
 1323 
 1324 ** The new function 'buffer-hash' computes a fast, non-consing hash of
 1325 a buffer's contents.
 1326 
 1327 ** 'interrupt-process' now consults the list 'interrupt-process-functions',
 1328 to determine which function has to be called in order to deliver the
 1329 SIGINT signal.  This allows Tramp to send the SIGINT signal to remote
 1330 asynchronous processes.  The hitherto existing implementation has been
 1331 moved to 'internal-default-interrupt-process'.
 1332 
 1333 ** The new function 'read-multiple-choice' prompts for multiple-choice
 1334 questions, with a handy way to display help texts.
 1335 
 1336 ** 'comment-indent-function' values may now return a cons to specify a
 1337 range of indentation.
 1338 
 1339 ** New optional argument TEXT in 'make-temp-file'.
 1340 
 1341 ** New function 'define-symbol-prop'.
 1342 
 1343 ** New function 'secure-hash-algorithms' to list the algorithms that
 1344 'secure-hash' supports.
 1345 See the node "(elisp) Checksum/Hash" in the ELisp manual for details.
 1346 
 1347 ** Emacs now exposes the GnuTLS cryptographic API with the functions
 1348 'gnutls-macs' and 'gnutls-hash-mac'; 'gnutls-digests' and
 1349 'gnutls-hash-digest'; 'gnutls-ciphers' and 'gnutls-symmetric-encrypt'
 1350 and 'gnutls-symmetric-decrypt'.
 1351 See the node "(elisp) GnuTLS Cryptography" in the ELisp manual for details.
 1352 
 1353 ** The function 'gnutls-available-p' now returns a list of capabilities
 1354 supported by the GnuTLS library used by Emacs.
 1355 
 1356 ** Emacs now supports records for user-defined types, via the new
 1357 functions 'make-record', 'record', and 'recordp'.  Records are now
 1358 used internally to represent cl-defstruct and defclass instances, for
 1359 example.
 1360 
 1361 If your program defines new record types, you should use
 1362 package-naming conventions for naming those types.  This is so any
 1363 potential conflicts with other types are avoided.
 1364 
 1365 ** 'save-some-buffers' now uses 'save-some-buffers-default-predicate'
 1366 to decide which buffers to ask about, if the PRED argument is nil.
 1367 The default value of 'save-some-buffers-default-predicate' is nil,
 1368 which means ask about all file-visiting buffers.
 1369 
 1370 ** string-(to|as|make)-(uni|multi)byte are now declared obsolete.
 1371 
 1372 ** New variable 'while-no-input-ignore-events' which allow
 1373 setting which special events 'while-no-input' should ignore.
 1374 It is a list of symbols.
 1375 
 1376 ** New function 'undo-amalgamate-change-group' to get rid of
 1377 undo-boundaries between two states.
 1378 
 1379 ** New var 'definition-prefixes' is a hash table mapping prefixes to
 1380 the files where corresponding definitions can be found.  This can be
 1381 used to fetch definitions that are not yet loaded, for example for
 1382 'C-h f'.
 1383 
 1384 ** New var 'syntax-ppss-table' to control the syntax-table used in
 1385 'syntax-ppss'.
 1386 
 1387 ** 'define-derived-mode' can now specify an :after-hook form, which
 1388 gets evaluated after the new mode's hook has run.  This can be used to
 1389 incorporate configuration changes made in the mode hook into the
 1390 mode's setup.
 1391 
 1392 ** Autoload files are now generated without timestamps.
 1393 Set 'autoload-timestamps' to a non-nil value to get timestamps in
 1394 autoload files.
 1395 
 1396 ** 'gnutls-boot' now takes a parameter ':complete-negotiation' that
 1397 says that negotiation should complete even on non-blocking sockets.
 1398 
 1399 ** There is now a new variable 'flyspell-sort-corrections-function'
 1400 that allows changing the way corrections are sorted.
 1401 
 1402 ** The new command 'fortune-message' has been added, which displays
 1403 fortunes in the echo area.
 1404 
 1405 ** New function 'func-arity' returns information about the argument list
 1406 of an arbitrary function.  This generalizes 'subr-arity' for functions
 1407 that are not built-in primitives.  We recommend using this new
 1408 function instead of 'subr-arity'.
 1409 
 1410 ** New function 'region-bounds' can be used in the interactive spec
 1411 to provide region boundaries (for rectangular regions more than one)
 1412 to an interactively callable function as a single argument instead of
 1413 two separate arguments 'region-beginning' and 'region-end'.
 1414 
 1415 ** 'parse-partial-sexp' state has a new element.  Element 10 is
 1416 non-nil when the last character scanned might be the first character
 1417 of a two character construct, i.e., a comment delimiter or escaped
 1418 character.  Its value is the syntax of that last character.
 1419 
 1420 ** 'parse-partial-sexp's state, element 9, has now been confirmed as
 1421 permanent and documented, and may be used by Lisp programs.  Its value
 1422 is a list of currently open parenthesis positions, starting with the
 1423 outermost parenthesis.
 1424 
 1425 ** 'read-color' will now display the color names using the color itself
 1426 as the background color.
 1427 
 1428 ** The function 'redirect-debugging-output' now works on platforms
 1429 other than GNU/Linux.
 1430 
 1431 ** The new function 'string-version-lessp' compares strings by
 1432 interpreting consecutive runs of numerical characters as numbers, and
 1433 compares their numerical values.  According to this predicate,
 1434 "foo2.png" is smaller than "foo12.png".
 1435 
 1436 ** Numeric comparisons and 'logb' no longer return incorrect answers
 1437 due to internal rounding errors.  For example, '(< most-positive-fixnum
 1438 (+ 1.0 most-positive-fixnum))' now correctly returns t on 64-bit hosts.
 1439 
 1440 ** The functions 'ffloor', 'fceiling', 'ftruncate' and 'fround' now
 1441 accept only floating-point arguments, as per their documentation.
 1442 Formerly, they quietly accepted integer arguments and sometimes
 1443 returned nonsensical answers, e.g., '(< N (ffloor N))' could return t.
 1444 
 1445 ** On hosts like GNU/Linux x86-64 where a 'long double' fraction
 1446 contains at least EMACS_INT_WIDTH - 3 bits, 'format' no longer returns
 1447 incorrect answers due to internal rounding errors when formatting
 1448 Emacs integers with '%e', '%f', or '%g' conversions.  For example, on
 1449 these hosts '(eql N (string-to-number (format "%.0f" N)))' now returns
 1450 t for all Emacs integers N.
 1451 
 1452 ** Calls that accept floating-point integers (for use on hosts with
 1453 limited integer range) now signal an error if arguments are not
 1454 integral.  For example '(decode-char 'ascii 0.5)' now signals an
 1455 error.
 1456 
 1457 ** Functions 'string-trim-left', 'string-trim-right' and 'string-trim'
 1458 now accept optional arguments which specify the regexp of a substring
 1459 to trim.
 1460 
 1461 ** The new function 'char-from-name' converts a Unicode name string
 1462 to the corresponding character code.
 1463 
 1464 ** New functions 'sxhash-eq' and 'sxhash-eql' return hash codes of a
 1465 Lisp object suitable for use with 'eq' and 'eql' correspondingly.  If
 1466 two objects are 'eq' ('eql'), then the result of 'sxhash-eq'
 1467 ('sxhash-eql') on them will be the same.
 1468 
 1469 ** Function 'sxhash' has been renamed to 'sxhash-equal' for
 1470 consistency with the new functions.  For compatibility, 'sxhash'
 1471 remains as an alias to 'sxhash-equal'.
 1472 
 1473 ** 'make-hash-table' now defaults to a rehash threshold of 0.8125
 1474 instead of 0.8, to avoid rounding glitches.
 1475 
 1476 ** New function 'add-variable-watcher' can be used to call a function
 1477 when a symbol's value is changed.  This is used to implement the new
 1478 debugger command 'debug-on-variable-change'.
 1479 
 1480 ** New variable 'print-escape-control-characters' causes 'prin1' and
 1481 'print' to output control characters as backslash sequences.
 1482 
 1483 ** Time conversion functions that accept a time zone rule argument now
 1484 allow it to be OFFSET or a list (OFFSET ABBR), where the integer
 1485 OFFSET is a count of seconds east of Universal Time, and the string
 1486 ABBR is a time zone abbreviation.  The affected functions are
 1487 'current-time-string', 'current-time-zone', 'decode-time',
 1488 'format-time-string', and 'set-time-zone-rule'.
 1489 
 1490 ** 'format-time-string' now formats '%q' to the calendar quarter.
 1491 
 1492 ** New built-in function 'mapcan'.
 1493 It avoids unnecessary consing (and garbage collection).
 1494 
 1495 ** 'car' and 'cdr' compositions 'cXXXr' and 'cXXXXr' are now part of Elisp.
 1496 
 1497 ** 'gensym' is now part of Elisp.
 1498 
 1499 ** Low-level list functions like 'length' and 'member' now do a better
 1500 job of signaling list cycles instead of looping indefinitely.
 1501 
 1502 ** The new functions 'make-nearby-temp-file' and 'temporary-file-directory'
 1503 can be used for creation of temporary files on remote or mounted directories.
 1504 
 1505 ** On GNU platforms when operating on a local file, 'file-attributes'
 1506 no longer suffers from a race when called while another process is
 1507 altering the filesystem.  On non-GNU platforms 'file-attributes'
 1508 attempts to detect the race, and returns nil if it does so.
 1509 
 1510 ** The new function 'file-local-name' can be used to specify arguments
 1511 of remote processes.
 1512 
 1513 ** The new functions 'file-name-quote', 'file-name-unquote' and
 1514 'file-name-quoted-p' can be used to quote / unquote file names with
 1515 the prefix "/:".
 1516 
 1517 ** The new error 'file-missing', a subcategory of 'file-error', is now
 1518 signaled instead of 'file-error' if a file operation acts on a file
 1519 that does not exist.
 1520 
 1521 ** The function 'delete-directory' no longer signals an error when
 1522 operating recursively and when some other process deletes the directory
 1523 or its files before 'delete-directory' gets to them.
 1524 
 1525 ** New error type 'user-search-failed' like 'search-failed' but
 1526 avoids debugger like 'user-error'.
 1527 
 1528 ** The function 'line-number-at-pos' now takes a second optional
 1529 argument 'absolute'.  If this parameter is nil, the default, this
 1530 function keeps on returning the line number taking potential narrowing
 1531 into account.  If this parameter is non-nil, the function ignores
 1532 narrowing and returns the absolute line number.
 1533 
 1534 ** The function 'color-distance' now takes a second optional argument
 1535 'metric'.  When non-nil, it should be a function of two arguments that
 1536 accepts two colors and returns a number.
 1537 
 1538 ** Changes in Frame and Window Handling
 1539 
 1540 *** Resizing a frame no longer runs 'window-configuration-change-hook'.
 1541 'window-size-change-functions' should be used instead.
 1542 
 1543 *** The new function 'frame-size-changed-p' can tell whether a frame has
 1544 been resized since the last time 'window-size-change-functions' has been
 1545 run.
 1546 
 1547 *** The function 'frame-geometry' now also returns the width of a
 1548 frame's outer border.
 1549 
 1550 *** New frame parameters and changed semantics for older ones:
 1551 
 1552 **** 'z-group' positions a frame above or below all others.
 1553 
 1554 **** 'min-width' and 'min-height' specify the absolute minimum size of a
 1555 frame.
 1556 
 1557 **** 'parent-frame' makes a frame the child frame of another Emacs
 1558 frame.  The section "(elisp) Child Frames" in the ELisp manual
 1559 describes the intrinsics of that relationship.
 1560 
 1561 **** 'delete-before' triggers deletion of one frame before that of
 1562 another.
 1563 
 1564 **** 'mouse-wheel-frame' specifies another frame whose windows shall be
 1565 scrolled instead.
 1566 
 1567 **** 'no-other-frame' has 'next-frame' and 'previous-frame' skip this
 1568 frame.
 1569 
 1570 **** 'skip-taskbar' removes a frame's icon from the taskbar and has
 1571 'Alt-<TAB>' skip this frame.
 1572 
 1573 **** 'no-focus-on-map' avoids that a frame gets input focus when mapped.
 1574 
 1575 **** 'no-accept-focus' means that a frame does not want to get input
 1576 focus via the mouse.
 1577 
 1578 **** 'undecorated' removes the window manager decorations from a frame.
 1579 
 1580 **** 'override-redirect' tells the window manager to disregard this
 1581 frame.
 1582 
 1583 **** 'width' and 'height' now allow the specification of pixel values
 1584 and ratios.
 1585 
 1586 **** 'left' and 'top' now allow the specification of ratios.
 1587 
 1588 **** 'keep-ratio' preserves size and position of child frames when their
 1589 parent frame is resized.
 1590 
 1591 **** 'no-special-glyphs' suppresses display of truncation and
 1592 continuation glyphs in a frame.
 1593 
 1594 **** 'auto-hide-function' and 'minibuffer-exit' handle auto hiding of
 1595 frames and exiting from minibuffer individually.
 1596 
 1597 **** 'fit-frame-to-buffer-margins' and 'fit-frame-to-buffer-sizes'
 1598 handle fitting a frame to its buffer individually.
 1599 
 1600 **** 'drag-internal-border', 'drag-with-header-line',
 1601 'drag-with-mode-line', 'snap-width', 'top-visible' and 'bottom-visible'
 1602 allow dragging and resizing frames with the mouse.
 1603 
 1604 **** 'minibuffer' is now set to the default minibuffer window when
 1605 initially specified as nil and is not reset to nil when initially
 1606 specifying a minibuffer window.
 1607 
 1608 *** The new function 'frame-list-z-order' returns a list of all frames
 1609 in Z (stacking) order.
 1610 
 1611 *** The function 'x-focus-frame' optionally tries to not activate its
 1612 frame.
 1613 
 1614 *** The variable 'focus-follows-mouse' has a third meaningful value
 1615 'auto-raise' to indicate that the window manager automatically raises a
 1616 frame when the mouse pointer enters it.
 1617 
 1618 *** The new function 'frame-restack' puts a frame above or below
 1619 another on the display.
 1620 
 1621 *** The new face 'internal-border' specifies the background of a frame's
 1622 internal border.
 1623 
 1624 *** The NORECORD argument of 'select-window' now has a meaningful value
 1625 'mark-for-redisplay' which is like any other non-nil value but marks
 1626 WINDOW for redisplay.
 1627 
 1628 *** Support for side windows is now official.  The display action
 1629 function 'display-buffer-in-side-window' will display its buffer in a
 1630 side window.  Functions for toggling all side windows on a frame,
 1631 changing and reversing the layout of side windows and returning the
 1632 main (major non-side) window of a frame are provided.  For details
 1633 consult the section "(elisp) Side Windows" in the ELisp manual.
 1634 
 1635 *** Support for atomic windows - rectangular compositions of windows
 1636 treated by 'split-window', 'delete-window' and 'delete-other-windows'
 1637 like a single live window - is now official.  For details consult the
 1638 section "(elisp) Atomic Windows" in the ELisp manual.
 1639 
 1640 *** New 'display-buffer' alist entry 'window-parameters' allows the
 1641 assignment of window parameters to the window used for displaying the
 1642 buffer.
 1643 
 1644 *** New function 'display-buffer-reuse-mode-window' is an action function
 1645 suitable for use in 'display-buffer-alist'.  For example, to avoid
 1646 creating a new window when opening man pages when there's already one,
 1647 use
 1648 
 1649 (add-to-list 'display-buffer-alist
 1650      '("\\`\\*Man .*\\*\\'" .
 1651        (display-buffer-reuse-mode-window
 1652         (inhibit-same-window . nil)
 1653         (mode . Man-mode))))
 1654 
 1655 *** New window parameter 'no-delete-other-windows' prevents that
 1656 its window gets deleted by 'delete-other-windows'.
 1657 
 1658 *** New window parameters 'mode-line-format' and 'header-line-format'
 1659 allow the buffer-local formats for this window to be overridden.
 1660 
 1661 *** New command 'window-swap-states' swaps the states of two live
 1662 windows.
 1663 
 1664 *** New functions 'window-pixel-width-before-size-change' and
 1665 'window-pixel-height-before-size-change' support detecting which
 1666 window changed size when 'window-size-change-functions' are run.
 1667 
 1668 *** The new function 'window-lines-pixel-dimensions' returns the pixel
 1669 dimensions of a window's text lines.
 1670 
 1671 *** The new function 'window-largest-empty-rectangle' returns the
 1672 dimensions of the largest rectangular area not occupying any text in a
 1673 window's body.
 1674 
 1675 *** The semantics of 'mouse-autoselect-window' has changed slightly.
 1676 For details see the section "(elisp) Mouse Window Auto-selection" in
 1677 the ELisp manual.
 1678 
 1679 *** 'select-frame-by-name' now may return a frame on another display
 1680 if it does not find a suitable one on the current display.
 1681 
 1682 ** 'tcl-auto-fill-mode' is now declared obsolete.  Its functionality
 1683 can be replicated simply by setting 'comment-auto-fill-only-comments'.
 1684 
 1685 ** New pcase pattern 'rx' to match against an rx-style regular expression.
 1686 For details, see the doc string of 'rx--pcase-macroexpander'.
 1687 
 1688 ** New functions to set region from secondary selection and vice versa.
 1689 The new functions 'secondary-selection-to-region' and
 1690 'secondary-selection-from-region' let you set the beginning and the
 1691 end of the region from those of the secondary selection and vice
 1692 versa.
 1693 
 1694 ** New function 'lgstring-remove-glyph' can be used to modify a
 1695 gstring returned by the underlying layout engine (e.g. m17n-flt,
 1696 uniscribe).
 1697 
 1698 
 1699 * Changes in Emacs 26.1 on Non-Free Operating Systems
 1700 
 1701 ** Intercepting hotkeys on Windows 7 and later now works better.
 1702 The new keyboard hooking code properly grabs system hotkeys such as
 1703 'Win-*' and 'Alt-TAB', in a way that Emacs can get at them before the
 1704 system.  This makes the 'w32-register-hot-key' functionality work
 1705 again on all versions of MS-Windows starting with Windows 7.  On
 1706 Windows NT and later you can now register any hotkey combination.  (On
 1707 Windows 9X, the previous limitations, spelled out in the Emacs manual,
 1708 still apply.)
 1709 
 1710 ** 'convert-standard-filename' no longer mirrors slashes on MS-Windows.
 1711 Previously, on MS-Windows this function converted slash characters in
 1712 file names into backslashes.  It no longer does that.  If your Lisp
 1713 program used 'convert-standard-filename' to prepare file names to be
 1714 passed to subprocesses (which is not the recommended usage of that
 1715 function), you will now have to mirror slashes in your application
 1716 code.  One possible way is this:
 1717 
 1718          (let ((start 0))
 1719            (while (string-match "/" file-name start)
 1720              (aset file-name (match-beginning 0) ?\\)
 1721              (setq start (match-end 0))))
 1722 
 1723 ** GUI sessions on MS-Windows now treat SIGINT like Posix platforms do.
 1724 The effect of delivering a Ctrl-C (SIGINT) signal to a GUI Emacs on
 1725 MS-Windows is now the same as on Posix platforms -- Emacs saves the
 1726 session and exits.  In particular, this will happen if you start
 1727 emacs.exe from the Windows shell, then type Ctrl-C into that shell's
 1728 window.
 1729 
 1730 ** 'signal-process' supports SIGTRAP on Windows XP and later.
 1731 The 'kill' emulation on Windows now maps SIGTRAP to a call to the
 1732 'DebugBreakProcess' API.  This causes the receiving process to break
 1733 execution and return control to the debugger.  If no debugger is
 1734 attached to the receiving process, the call is typically ignored.
 1735 This is in contrast to the default action on POSIX Systems, where it
 1736 causes the receiving process to terminate with a core dump if no
 1737 debugger has been attached to it.
 1738 
 1739 ** 'set-mouse-position' and 'set-mouse-absolute-pixel-position' work
 1740 on macOS.
 1741 
 1742 ** Emacs can now be run as a GUI application from the command line on
 1743 macOS.
 1744 
 1745 ** 'ns-appearance' and 'ns-transparent-titlebar' change the appearance
 1746 of frame decorations on macOS 10.9+.
 1747 
 1748 ** 'ns-use-thin-smoothing' enables thin font smoothing on macOS 10.8+.
 1749 
 1750 ** 'process-attributes' on Darwin systems now returns more information.
 1751 
 1752 ** Mousewheel and trackpad scrolling on macOS 10.7+ now behaves more
 1753 like the macOS default.  The new variables 'ns-mwheel-line-height',
 1754 'ns-use-mwheel-acceleration' and 'ns-use-mwheel-momentum' can be used
 1755 to customize the behavior.
 1756 
 1757 
 1758 ----------------------------------------------------------------------
 1759 This file is part of GNU Emacs.
 1760 
 1761 GNU Emacs is free software: you can redistribute it and/or modify
 1762 it under the terms of the GNU General Public License as published by
 1763 the Free Software Foundation, either version 3 of the License, or
 1764 (at your option) any later version.
 1765 
 1766 GNU Emacs is distributed in the hope that it will be useful,
 1767 but WITHOUT ANY WARRANTY; without even the implied warranty of
 1768 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 1769 GNU General Public License for more details.
 1770 
 1771 You should have received a copy of the GNU General Public License
 1772 along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
 1773 
 1774 
 1775 Local variables:
 1776 coding: utf-8
 1777 mode: outline
 1778 paragraph-separate: "[ 	]*$"
 1779 end: