@c This is part of the Emacs manual.
@c Copyright (C) 1997, 1999, 2000 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.

@node Antinews, Mac OS, Command Arguments, Top
@appendix Emacs 20 Antinews

  For those users who live backwards in time, here is information about
downgrading to Emacs version 20.  We hope you will enjoy the greater
simplicity that results from the absence of many Emacs 21 features.

@itemize @bullet
@item
The display engine has been greatly simplified by eliminating support
for variable-size characters and other non-text display features.  This
avoids the complexity of display layout in Emacs 21.  To wit:

@itemize @minus
@item
Variable-size characters are not supported in Emacs 20.  You cannot use
fonts which contain oversized characters, and using italics fonts can
results in illegible display.  However, text which uses variable-size
fonts is unreadable anyway.  With all characters in a frame layed out on
a regular grid, each character having the same height and width, text is
much easier to read.

@item
Emacs does not display images, or play sounds.  It just displays text,
as you would expect from a @strong{text} editor.

@item
Specification of the font for a face now uses an XLFD font name, for
compatibility with other X applications.  This means that font
attributes cannot be merged when combining faces; however, experience
shows that mergers are bad economics.  Face inheritance has also been
removed, so no one can accumulate ``too much face.''

@item
Several face appearance attributes such as 3D appearence,
strike-through, and overline, have been eliminated.

@item
Emacs now provides its own ``lean and mean'' scroll bars instead using
those from the X toolkit.  Toggle buttons and radio buttons in menus now
look just like any other menu item, which simplifies them, and prevents
them from standing out and distracting your attention from the other
menu items.

@item
There are no toolbars and no tooltips; in particular, @acronym{GUD}
mode cannot display variable values in a tooltip when you click on
that variable's name.  Instead, Emacs 20 provides a direct interface to
the debugger, so that you can type appropriate debugger commands, such
as @kbd{display foo} and @kbd{print bar}.  As these commands use
explicit words, their meaning is more self-evident.

@item
Colors are not available on character terminals.  If you @emph{must}
have colors, but cannot afford running X, you can now use the MS-DOG
version of Emacs inside a DOS emulator.

@item
The mode line is not mouse-sensitive, since it is meant only to
display information.  Use keyboard commands to switch between buffers,
toggle read-only and modified status, switch minor modes on and off,
etc.

@item
The support for ``wheeled'' mice under X has been removed, because
of their slow scroll rate, and because you will find less and less of
these mice as you go back in time.  Instead Emacs 20 provides the
@kbd{C-v} and @kbd{M-v} keys for scrolling.  (You can also use the
scroll bar, but be advised that it, too, may be absent in yet earlier
Emacs versions.)

@item
Busy-cursor display is gone, as it was found to be too hard to draw on
displays whose resolution is getting lower and lower.  This means that
you get the standard kind of cursor blinking that your terminal
provides.

@item
Some aspects of Emacs appearance, such as the colors of the scroll bar
and the menus, can only be controlled via X resources.  Since colors
aren't supported except on X, it doesn't make any sense doing this in
any way but the X way.  For those users who aren't privy to X arcana,
we've provided good default colors that should make everybody happy.

@item
The variable @code{show-trailing-whitespace} has no special meaning, so
trailing whitespace on a line is now always displayed correctly: as
empty space.  To see if a line ends with spaces or TABs, type @kbd{C-e}
on that line.  Likewise, empty lines at the end of the buffer are not
marked in any way; use @kbd{M->} to see where the end of the buffer is.

@item
The spacing between text lines on the display now always follows the
font design and the rules of your window manager.  This provides for
predictable appearance of the displayed text.
@end itemize

@item
Emacs 20 has simpler support for multi-lingual editing.  While not as
radical a simplification as Emacs 19 was, it goes a long way toward
eliminating some of the annoying features:

@itemize @minus
@item
Translations of the Emacs reference cards to other languages are no
longer part of the distribution, because in the past we expect
computer users to speak English.

@item
To avoid extra confusion, many language environments have been
eliminated.  For example, @samp{Polish} and @samp{Celtic} (Latin-8)
environments are not supported.  The Latin-9 environment is gone,
too, because you won't need the Euro sign in the past.

@item
Emacs 20 always asks you which coding system to use when saving 
a buffer, unless it can use the same one that it used to read the buffer.
It does not try to see if the preferred coding system is suitable.

@item
Commands which provide detailed information about character sets and
coding systems, such as @code{list-charset-chars},
@code{describe-character-set}, and the @kbd{C-u C-x =} key-sequence,
no longer exist.  The less said about non-@sc{ascii} characters, the
better.

@item
The terminal coding system cannot be set to something CCL-based, so
keyboards which produce @code{KOI8} and DOS/Windows codepage codes
cannot be supported directly.  Instead, you should use one of the input
methods provided in the Leim package.
@end itemize

@item
As you move back through time, some systems will become unimportant or
enter the vaporware phase, so Emacs 20 does not support them:

@itemize @minus
@item
Emacs 20 cannot be built on GNU/Linux systems running on IA64 machines,
and you cannot build a 64-bit Emacs on Solaris or Irix even though there
are still 64-bit versions of those OSes.

@item
LynxOS is also not supported, and neither is the Macintosh, though they
still exist.
@end itemize

@item
The arrangement of menu bar items differs from most other @acronym{GUI}
programs.  We think that uniformity of look-and-feel is boring, and that
Emacs' unique features require its unique menu-bar configuration.

@item
You cannot save the options that you set from the @samp{Options}
menu-bar menu; instead, you need to set all the options again each time
you start a new session.  However, if you follow the recommended
practice and keep a single Emacs session running until you log out,
you won't have to set the options very often.

@item
Emacs 20 does not pop up a buffer with error messages when an error is
signaled during loading of the user's init file.  Instead, it simply
announces the fact that an error happened.  To know where in the init
file was that, insert @code{(message "foo")} lines judiciously into the
file and look for those messages in the @samp{*Messages*} buffer.

@item
Some commands no longer treat Transient Mark mode specially.  For
example, @code{ispell} doesn't spell-check the region when Transient
Mark mode is in effect and the mark is active; instead, it checks the
current buffer.  (Transient Mark mode is alien to the spirit of Emacs,
so we are planning to remove it altogether in an earlier version.)

@item
@kbd{C-Down-Mouse-3} does not show what would be in the menu bar
when the menu bar is not displayed.

@item
For uniformity, @key{delete} function key in Emacs 20 works exactly like
the @key{DEL} key, on both text-only terminals and window systems---it
always deletes backward.  This eliminates the inconsistency of Emacs 21,
where the key labeled @key{delete} deletes forward when you are using a
window system, and backward on a text-only terminals.

@item
The ability to place backup files in special subdirectories (controlled
by @code{backup-directory-alist}) has been eliminated.  This makes
finding your backup files much easier: they are always in the same
directory as the original files.

@item
Emacs no longer refuses to load Lisp files compiled by incompatible
versions of Emacs, which may contain invalid byte-code.  Instead,
Emacs now dumps core when it encounters such byte-code.  However, this
is a rare occurrence, and it won't happen at all when all Emacs
versions merge together, in the distant past.

@item
The @kbd{C-x 5 1} command has been eliminated.  If you want to delete
all the frames but the current one, delete them one by one instead.

@item
CC Mode now enforces identical values for some customizable options,
such as indentation style, for better consistency.  In particular, if
you select an indentation style for Java, the same style is used
for C and C@t{++} buffer as well.

@item
Isearch does not highlight other possible matches; it shows only the
current match, to avoid distracting your attention.  @kbd{Mouse-2} in
the echo area during incremental search now signals an error, instead of
inserting the current selection into the search string.  But you can
accomplish more or less the same job by typing @kbd{M-y}.

@item
The ability to specify a port number when editing remote files with
@code{ange-ftp} was removed.  Instead, Emacs 20 provides undocumented
features in the function @code{ange-ftp-normal-login} (@cite{Use the
source, Luke!}) to specify the port.

@item
Emacs 20 does not check for changing time stamps of remote files, since
the old FTP programs you will encounter in the past could not provide
the time stamp anyway.  Windows-style FTP clients which output the
@samp{^M} character at the end of each line get special handling from
@code{ange-ftp} in Emacs 20, with unexpected results that should make
your life more interesting.

@item
Many complicated display features, including highlighting of
mouse-sensitive text regions and popping up help strings for menu items,
don't work in the MS-DOS version.  Spelling doesn't work on MS-DOS,
and Eshell doesn't exist, so there's no workable shell-mode, either.
This fits the spirit of MS-DOS, which resembles a dumb character
terminal.

@item
The @code{woman} package has been removed, so Emacs users on non-Posix
systems will need @emph{a real man} to read manual pages.  (Users who
are not macho can read the Info documentation instead.)

@item
@code{recentf} has been removed, because we figure that you can remember
the names of the files you edit frequently.  With decreasing disk size,
you should have fewer files anyway, so you won't notice the absence of
this feature.

@item
The @code{field} property does not exist in Emasc 20, so various
packages that run subsidiary programs in Emacs buffers cannot in general
distinguish which text was user input and which was output from the
subprocess.  If you need to try to do this nonetheless, Emacs 20
provides a variable @code{comint-prompt-regexp}, which lets you try to
distinguish input by recognizing prompt strings.

@item
We have eliminated the special major modes for Delphi sources,
PostScript files, context diffs, and @file{TODO} files.  Use Fundamental
Mode instead.

@item
Many additional packages that unnecessarily complicate your life in
Emacs 21 are absent in Emacs 20.  You cannot browse C@t{++} classes with
Ebrowse, access @acronym{SQL} data bases, access @acronym{LDAP} and
other directory servers, or mix shell commands and Lisp functions using
Eshell.

@item
To keep up with decreasing computer memory capacity and disk space, many
other functions and files have been eliminated in Emacs 20.
@end itemize
