XEmacs 21.2-b1

[chise/xemacs-chise.git.1] / PROBLEMS

                                                  -*- mode:outline -*-

This file describes various problems that have been encountered
in compiling, installing and running XEmacs.  It has been updated for
XEmacs 21.2.

This file is rather large, but we have tried to sort the entries by
their respective relevance for XEmacs, but may have not succeeded
completely in that task.  The file is divided into four parts:

 - Problems with building XEmacs
 - Problems with running XEmacs
 - Compatibility problems
 - Mule issues

Use `C-c C-f' to move to the next equal level of outline, and
`C-c C-b' to move to previous equal level.  `C-h m' will give more
info about the Outline mode.

Also, Try finding the things you need using one of the search commands
XEmacs provides (e.g. `C-s').

A general advice:
    WATCH OUT for .emacs file!  ~/.emacs is your Emacs init file.  If
    you observe strange problems, invoke XEmacs with the `-q' option
    and see if you can repeat the problem.


* Problems with building XEmacs
===============================

** Don't use -O2 with gcc 2.7.2 under Intel/XXX without also using
`-fno-strength-reduce'.

gcc will generate incorrect code otherwise.  This bug is present in at
least 2.6.x and 2.7.[0-2].  This bug has been fixed in GCC 2.7.2.1 and
later.  This bug is O/S independent, but is limited to x86 architectures.

This problem is known to be fixed in egcs (or pgcc) 1.0 or later.

** Don't use -O2 with gcc 2.7.2 under Intel architectures without also
using `-fno-caller-saves'.

gcc will generate incorrect code otherwise.  This bug is still
present in gcc 2.7.2.3.  There have been no reports to indicate the
bug is present in egcs 1.0 (or pgcc 1.0) or later.  This bug is O/S
independent, but limited to x86 architectures.

This problem is known to be fixed in egcs (or pgcc) 1.0 or later.

** Excessive optimization with pgcc can break XEmacs

It has been reported on some systems that compiling with -O6 can lead
to XEmacs failures.  The workaround is to use a lower optimization
level.  -O2 and -O4 have been tested extensively.

All of this depends heavily on the version of pgcc and the version
of libc.  Snapshots near the release of pgcc-1.0 have been tested
extensively and no sign of breakage has been seen on systems using
glibc-2.

** `compress' and `uncompress' not found and XFree86

XFree86 installs a very old version of libz.a by default ahead of where
more modern version of libz might be installed.  This will cause problems
when attempting to link against libMagick.  The fix is to remove the old
libz.a in the X11 binary directory.

** Excessive optimization on AIX 4.2 can lead to compiler failure.

Valdis.Kletnieks@vt.edu writes:
  At least at the b34 level, and the latest-and-greatest IBM xlc
  (3.1.4.4), there are problems with -O3.  I haven't investigated
  further.

** Sed problems on Solaris 2.5

There have been reports of Sun sed truncating very lines in the
Makefile during configuration.  The workaround is to use GNU sed or,
even better, think of a better way to generate Makefile, and send us a 
patch. :-)

** test-distrib says that the distribution has been clobbered
or, temacs prints "Command key out of range 0-127"
or, temacs runs and dumps xemacs, but xemacs totally fails to work.
or, temacs gets errors dumping xemacs

This can be because the .elc files have been garbled.  Do not be
fooled by the fact that most of a .elc file is text: these are binary
files and can contain all 256 byte values.

In particular `shar' cannot be used for transmitting GNU Emacs.  It
typically truncates "lines".  (this does not apply to GNU shar, which
uses uuencode to encode binary files.)

If you have a copy of Emacs that has been damaged in its nonprinting
characters, you can fix them by running:

 make all-elc

This will rebuild all the needed .elc files.

** `Error: No ExtNode to pop!' on Linux systems with Lesstif.

This error message has been observed with lesstif-0.75a.  It does not
appear to cause any harm.

** Linking with -rpath on IRIX.

Darrell Kindred <dkindred@cmu.edu> writes:
There are a couple of problems [with use of -rpath with Irix ld], though:

  1. The ld in IRIX 5.3 ignores all but the last -rpath
     spec, so the patched configure spits out a warning
     if --x-libraries or --site-runtime-libraries are
     specified under irix 5.x, and it only adds -rpath 
     entries for the --site-runtime-libraries.  This bug was
     fixed sometime between 5.3 and 6.2.

  2. IRIX gcc 2.7.2 doesn't accept -rpath directly, so
     it would have to be prefixed by -Xlinker or "-Wl,".
     This would be fine, except that configure compiles with
        ${CC-cc} $CFLAGS $LDFLAGS ...
     rather than quoting $LDFLAGS with prefix-args, like
     src/Makefile does.  So if you specify --x-libraries
     or --site-runtime-libraries, you must use --use-gcc=no,
     or configure will fail.

** On Irix 6.3, the SGI ld quits with segmentation fault when linking temacs

This occurs if you use the SGI linker version 7.1.  Installing the
patch SG0001872 fixes this problem.

** xemacs: can't resolve symbol '__malloc_hook'

This is a Linux problem where you've compiled the XEmacs binary on a libc
5.4 with version higher than 5.4.19 and attempted to run the binary against
an earlier version.  The solution is to upgrade your old library.

** Compilation errors on VMS.

Sorry, XEmacs does not work under VMS.  You might consider working on
the port if you really want to have XEmacs work under VMS.

** On Solaris 2 I get undefined symbols from libcurses.a.

You probably have /usr/ucblib/ on your LD_LIBRARY_PATH.  Do the link with
LD_LIBRARY_PATH unset.  Generally, avoid using any ucb* stuff when
building XEmacs.

** On Solaris 2 I cannot make alloc.o, glyphs.o or process.o.

The SparcWorks C compiler may have difficulty building those modules
with optimization level -xO4.  Try using only "-fast" optimization
for just those modules.  (Or use gcc).

** On Digital UNIX, the DEC C compiler might have a problem compiling
some files.

In particular, src/extents.c and src/faces.c might cause the DEC C
compiler to abort.  When this happens: cd src, compile the files by
hand, cd .., and redo the "make" command.  When recompiling the files by
hand, use the old C compiler for the following versions of Digital UNIX:
  - V3.n: Remove "-migrate" from the compile command.
  - V4.n: Add "-oldc" to the compile command.

A related compiler bug has been fixed by the DEC compiler team.  The
new versions of the compiler should run fine.

** On HPUX, the HP C compiler might have a problem compiling some files
with optimization.

Richard Cognot <cognot@ensg.u-nancy.fr> writes:

  Had to drop once again to level 2 optimization, at least to
  compile lstream.c. Otherwise, I get a "variable is void: \if"
  problem while dumping (this is a problem I already reported
  with vanilla hpux 10.01 and 9.07, which went away after
  applying patches for the C compiler). Trouble is I still
  haven't found the same patch for hpux 10.10, and I don't
  remember the patch numbers. I think potential XEmacs builders
  on HP should be warned about this.

** I don't have `xmkmf' and `imake' on my HP.

  You can get these standard X tools by anonymous FTP to
  hpcvaaz.cv.hp.com.  Essentially all X programs need these.

** On HP-UX, problems with make

Marcus Thiessel <marcus_thiessel@hp.com>

  Some releases of XEmacs (e.g. 20.4) require GNU make to build
  successfully. You don't need GNU make when building 21.x.

** On HP-UX 9.05 XEmacs won't compile or coredump during the build.

Marcus Thiessel <marcus_thiessel@hp.com>

  This might be a sed problem. For your own safety make sure to use
  GNU sed while dumping XEmacs.

** On HP-UX 11.0 XEmacs causes excessive X11 errors when running.

Marcus Thiessel <marcus_thiessel@hp.com>

  Unfortunately, XEmacs releases don't work with Motif2.1. It
  will compile but you will get excessive X11 errors like

  xemacs: X Error of failed request:  BadGC (invalid GC parameter)

  and finally XEmacs gets killed. A workaround is to use the
  Motif1.2_R6 libraries. You can the following line to your call to
  configure:

     --x-libraries="/usr/lib/Motif1.2_R6 -L/usr/lib/X11R6"
 
  Make sure /usr/lib/Motif1.2_R6/libXm.sl is a link to
  /usr/lib/Motif1.2_R6/libXm.3.

** Solaris 2.3 /bin/sh coredumps during configuration.

This only occurs if you have LANG != C.  This is a known bug with
/bin/sh fixed by installing Patch-ID# 101613-01.  Or, you can use
bash, as a workaround.

** On Irix 6.0, make tries (and fails) to build a program named unexelfsgi

A compiler bug inserts spaces into the string "unexelfsgi . o"
in src/Makefile.  Edit src/Makefile, after configure is run,
find that string, and take out the spaces.

Compiler fixes in Irix 6.0.1 should eliminate this problem.

** Coredumping in Irix 6.2

Pete Forman <gsez020@compo.bedford.waii.com> writes:
A problem noted by myself and others (I've lost the references) was
that XEmacs coredumped when the cut or copy toolbar buttons were
pressed.  This has been fixed by loading the SGI patchset (Feb 98)
without having to recompile XEmacs.

My versions are XEmacs 20.3 (problem first noted in 19.15) and IRIX
6.2, compiled using -n32.  I'd guess that the relevant individual
patch was "SG0002580: multiple fixes for X libraries".  SGI recommends
that the complete patch set be installed rather than parts of it.

** Native cc on SCO OpenServer 5 is now OK.  Icc may still throw you
a curve.  Here is what Robert Lipe <robertl@arnet.com> says:

Unlike XEmacs 19.13, building with the native cc on SCO OpenServer 5 
now produces a functional binary.   I will typically build this
configuration for COFF with:

        /path_to_xemacs_source/configure --with-gcc=no \
          --site-includes=/usr/local/include --site-libraries=/usr/local/lib \
          --with-xpm --with-xface --with-sound=nas

This version now supports ELF builds.  I highly recommend this to 
reduce the in-core footprint of XEmacs.  This is now how I compile 
all my test releases.  Build it like this:

        /path_to_XEmacs_source/configure --with-gcc=no \
          --site-includes=/usr/local/include --site-libraries=/usr/local/lib \
          --with-xpm --with-xface --with-sound=nas --dynamic

The compiler known as icc [ supplied with the OpenServer 5 Development 
System ] generates a working binary, but it takes forever to generate
XEmacs.  ICC also whines more about the code than /bin/cc does.  I do
believe all its whining is legitimate, however.    Note that you do
have to 'cd src ; make  LD=icc' to avoid linker errors.

The way I handle the build procedure is:

        /path_to_XEmacs_source/configure --with-gcc=no \
          --site-includes=/usr/local/include --site-libraries=/usr/local/lib \
          --with-xpm --with-xface --with-sound=nas --dynamic --compiler="icc"

NOTE I have the xpm, xface, and audio libraries and includes in 
        /usr/local/lib, /usr/local/include.  If you don't have these,
        don't include the "--with-*" arguments in any of my examples.

In previous versions of XEmacs, you had to override the defaults while 
compiling font-lock.o and extents.o when building with icc.  This seems
to no longer be true, but I'm including this old information in case it
resurfaces.  The process I used was:

        make -k    
        [ procure pizza, beer, repeat ] 
        cd src
        make CC="icc -W0,-mP1COPT_max_tree_size=3000" font-lock.o extents.o
        make LD=icc

If you want sound support, get the tls566 supplement from 
ftp.sco.com:/TLS or any of its mirrors.  It works just groovy 
with XEmacs.

The M-x manual-entry is known not to work.  If you know Lisp and would
like help in making it work, e-mail me at <robertl@dgii.com>.
(UNCHECKED for 19.15 -- it might work).

In earlier releases, gnuserv/gnuclient/gnudoit would open a frame 
just fine, but the client would lock up and the server would
terminate when you used C-x # to close the frame.   This is now 
fixed in XEmacs.

In etc/ there are two files of note. emacskeys.sco and emacsstrs.sco.
The comments at the top of emacskeys.sco describe its function, and
the emacstrs.sco is a suitable candidate for /usr/lib/keyboard/strings
to take advantage of the keyboard map in emacskeys.sco.

Note: Much of the above entry is probably not valid for XEmacs 21.2
and later.

** Under some versions of OSF XEmacs runs fine if built without
optimization but will crash randomly if built with optimization.

Using 'cc -g' is not sufficient to eliminate all optimization.  Try
'cc -g -O0' instead.

** On SunOS, you get linker errors
    ld: Undefined symbol 
       _get_wmShellWidgetClass
       _get_applicationShellWidgetClass

The fix to this is to install patch 100573 for OpenWindows 3.0
or link libXmu statically.

** On Sunos 4, you get the error ld: Undefined symbol __lib_version.

This is the result of using cc or gcc with the shared library meant
for acc (the Sunpro compiler).  Check your LD_LIBRARY_PATH and delete
/usr/lang/SC2.0.1 or some similar directory.

** On AIX 4.1.2, linker error messages such as
   ld: 0711-212 SEVERE ERROR: Symbol .__quous, found in the global symbol table
         of archive /usr/lib/libIM.a, was not defined in archive member shr.o.

This is a problem in libIM.a.  You can work around it by executing
these shell commands in the src subdirectory of the directory where
you build Emacs:

    cp /usr/lib/libIM.a .
    chmod 664 libIM.a
    ranlib libIM.a

Then change -lIM to ./libIM.a in the command to link temacs (in
Makefile).

** On Irix 5.2, unexelfsgi.c can't find cmplrs/stsupport.h.

The file cmplrs/stsupport.h was included in the wrong file set in the
Irix 5.2 distribution.  You can find it in the optional fileset
compiler_dev, or copy it from some other Irix 5.2 system.  A kludgy
workaround is to change unexelfsgi.c to include sym.h instead of
syms.h.

** Link failure when using acc on a Sun.

To use acc, you need additional options just before the libraries, such as

   /usr/lang/SC2.0.1/values-Xt.o -L/usr/lang/SC2.0.1/cg87 -L/usr/lang/SC2.0.1

and you need to add -lansi just before -lc.

The precise file names depend on the compiler version, so we
cannot easily arrange to supply them.

** Link failure on IBM AIX 1.3 ptf 0013.

There is a real duplicate definition of the function `_slibc_free' in
the library /lib/libc_s.a (just do nm on it to verify).  The
workaround/fix is:

    cd /lib
    ar xv libc_s.a NLtmtime.o
    ar dv libc_s.a NLtmtime.o

** Undefined symbols when linking on Sunos 4.1.

If you get the undefined symbols _atowc _wcslen, _iswprint, _iswspace,
_iswcntrl, _wcscpy, and _wcsncpy, then you need to add -lXwchar after
-lXaw in the command that links temacs.

This problem seems to arise only when the international language
extensions to X11R5 are installed.

** src/Makefile and lib-src/Makefile are truncated--most of the file missing.

This can happen if configure uses GNU sed version 2.03.  That version
had a bug.  GNU sed version 2.05 works properly.

** On AIX, you get this compiler error message:

    Processing include file ./XMenuInt.h
        1501-106: (S) Include file X11/Xlib.h not found.

This means your system was installed with only the X11 runtime i.d
libraries.  You have to find your sipo (bootable tape) and install
X11Dev... with smit.

** C-z just refreshes the screen instead of suspending Emacs.

You are probably using a shell that doesn't support job control, even
though the system itself is capable of it.  Try using a different
shell.

** On a Sun running SunOS 4.1.1, you get this error message from GNU ld:

    /lib/libc.a(_Q_sub.o): Undefined symbol __Q_get_rp_rd referenced from text segment 

The problem is in the Sun shared C library, not in GNU ld.

The solution is to install Patch-ID# 100267-03 from Sun.

** SunOS 4.1.2: undefined symbol _get_wmShellWidgetClass

  Apparently the version of libXmu.so.a that Sun ships is hosed: it's missing
  some stuff that is in libXmu.a (the static version).  Sun has a patch for 
  this, but a workaround is to use the static version of libXmu, by changing
  the link command from "-lXmu" to "-Bstatic -lXmu -Bdynamic".  If you have
  OpenWindows 3.0, ask Sun for these patches:
    100512-02       4.1.x OpenWindows 3.0 libXt Jumbo patch
    100573-03       4.1.x OpenWindows 3.0 undefined symbols with shared libXmu

** Random other SunOS 4.1.[12] link errors.

  The X headers and libraries that Sun ships in /usr/{include,lib}/X11 are
  broken.  Use the ones in /usr/openwin/{include,lib} instead.

** When using gcc, you get the error message "undefined symbol __fixunsdfsi".
When using gcc, you get the error message "undefined symbol __main".

This means that you need to link with the gcc library.  It may be called
"gcc-gnulib" or "libgcc.a"; figure out where it is, and define LIB_GCC in
config.h to point to it.

It may also work to use the GCC version of `ld' instead of the standard one.

** When compiling with X11, you get "undefined symbol _XtStrings".

This means that you are trying to link emacs against the X11r4 version of
libXt.a, but you have compiled either Emacs or the code in the lwlib
subdirectory with the X11r5 header files.  That doesn't work.

Remember, you can't compile lwlib for r4 and emacs for r5, or vice versa.
They must be in sync.

** Problems finding X11 libraries on Solaris with Openwindows

Some users have reported problems in this area.  The reported solution
is to define the environment variable OPENWINHOME, even if you must set
it to `/usr/openwin'.

** Under Linux, you get "too many arguments to function `getpgrp'".

You have probably installed LessTiff under `/usr/local' and `libXm.so'
could not be found when linking `getpgrp()' test program, making XEmacs
think that `getpgrp()' takes an argument. Try adding `/usr/local/lib'
in `/etc/ld.so.conf' and run `ldconfig'. Then run XEmacs's `configure'
again.  As with all problems of this type, reading the config.log file
generated from configure and seeing the log of how the test failed can
prove enlightening.


* Problems with running XEmacs
==============================
** On Solaris 2.6, XEmacs dumps core when exiting.

This happens if you're XEmacs is running on the same machine as the X
server, and the optimized memory transport has been turned on by
setting the environment variable XSUNTRANSPORT.  The crash occurs
during the call to XCloseDisplay.

If this describes your situation, you need to undefine the
XSUNTRANSPORT environment variable.

** `C-z', or `M-x suspend-emacs' hangs instead of suspending.

If you build with `gpm' support on Linux, you cannot suspend XEmacs
because gpm installs a buggy SIGTSTP handler.  Either compile with
`--with-gpm=no', or don't suspend XEmacs on the Linux console until
this bug is fixed.

** You type Control-H (Backspace) expecting to delete characters.

Emacs has traditionally used Control-H for help; unfortunately this
interferes with its use as Backspace on TTY's.  One way to solve this
problem is to put this in your .emacs:

  (when (eq tty-erase-char ?\C-h)
    (keyboard-translate ?\C-h ?\C-?)
    (global-set-key "\M-?" 'help-command))

This checks whether the TTY erase char is C-h, and if it is, makes
Control-H (Backspace) work sensibly, and moves help to Meta-? (ESC ?).

Note that you can probably also access help using F1.

** Mail agents (VM, Gnus, rmail) cannot get new mail

rmail and VM get new mail from /usr/spool/mail/$USER using a program
called `movemail'.  This program interlocks with /bin/mail using the
protocol defined by /bin/mail.

There are two different protocols in general use.  One of them uses
the `flock' system call.  The other involves creating a lock file;
`movemail' must be able to write in /usr/spool/mail in order to do
this.  You control which one is used by defining, or not defining, the
macro MAIL_USE_FLOCK in config.h or the m- or s- file it includes.  IF
YOU DON'T USE THE FORM OF INTERLOCKING THAT IS NORMAL ON YOUR SYSTEM,
YOU CAN LOSE MAIL!

If your system uses the lock file protocol, and fascist restrictions
prevent ordinary users from writing the lock files in /usr/spool/mail,
you may need to make `movemail' setgid to a suitable group such as
`mail'.  To do this, use the following commands (as root) after doing
the make install.

        chgrp mail movemail
        chmod 2755 movemail

Installation normally copies movemail from the build directory to an
installation directory which is usually under /usr/local/lib.  The
installed copy of movemail is usually in the directory
/usr/local/lib/emacs/VERSION/TARGET.  You must change the group and
mode of the installed copy; changing the group and mode of the build
directory copy is ineffective.

** XEmacs crashes on Digital Unix within font-lock, or when dealing
with large compilation buffers.

The default stack size under Digital Unix is rather small (2M as
opposed to Solaris 8M), hosing the regexp code, which uses alloca()
extensively, overflowing the stack when complex regexps are used.
Workarounds:

1) Increase your stack size, using `ulimit -s 8192' or a (t)csh
   equivalent;

2) Recompile regex.c with REGEX_MALLOC defined.

** On Solaris, C-x doesn't get through to Emacs when you use the console.

This is a Solaris feature (at least on Intel x86 cpus).  Type C-r
C-r C-t, to toggle whether C-x gets through to Emacs.

** VM appears to hang in large folders.

This is normal (trust us) when upgrading to VM-6.22 from earlier
versions.  Let VM finish what it is doing and all will be well.

** Changes made to .el files do not take effect.

You may have forgotten to recompile them into .elc files.  Then the
old .elc files will be loaded, and your changes will not be seen.  To
fix this, do `M-x byte-recompile-directory' and specify the directory
that contains the Lisp files.

Note that you will get a warning when loading a .elc file that is
older than the corresponding .el file.

** Things which should be bold or italic (such as the initial
copyright notice) are not.

The fonts of the "bold" and "italic" faces are generated from the font
of the "default" face; in this way, your bold and italic fonts will
have the appropriate size and family.  However, emacs can only be
clever in this way if you have specified the default font using the
XLFD (X Logical Font Description) format, which looks like

        *-courier-medium-r-*-*-*-120-*-*-*-*-*-*

if you use any of the other, less strict font name formats, some of
which look like:

                lucidasanstypewriter-12
and             fixed
and             9x13

then emacs won't be able to guess the names of the "bold" and "italic"
versions.  All X fonts can be referred to via XLFD-style names, so you
should use those forms.  See the man pages for X(1), xlsfonts(1), and
xfontsel(1).

** The dumped Emacs crashes when run, trying to write pure data.

Two causes have been seen for such problems.

1) On a system where getpagesize is not a system call, it is defined
as a macro.  If the definition (in both unexec.c and malloc.c) is wrong,
it can cause problems like this.  You might be able to find the correct
value in the man page for a.out (5).

2) Some systems allocate variables declared static among the
initialized variables.  Emacs makes all initialized variables in most
of its files pure after dumping, but the variables declared static and
not initialized are not supposed to be pure.  On these systems you
may need to add "#define static" to the m- or the s- file.

** Reading and writing files is very very slow.

Try evaluating the form (setq lock-directory nil) and see if that helps.
There is a problem with file-locking on some systems (possibly related
to NFS) that I don't understand.  Please send mail to the address 
xemacs@xemacs.org if you figure this one out.

** The Emacs window disappears when you type M-q.

Some versions of the Open Look window manager interpret M-q as a quit
command for whatever window you are typing at.  If you want to use
Emacs with that window manager, you should try to configure the window
manager to use some other command.   You can disable the
shortcut keys entirely by adding this line to ~/.OWdefaults:

    OpenWindows.WindowMenuAccelerators: False

** The `Alt' key doesn't behave as `Meta' when running DECwindows.

The default DEC keyboard mapping has the Alt keys set up to generate the
keysym `Multi_key', which has a meaning to xemacs which is distinct from that
of the `Meta_L' and `Meta-R' keysyms.  A second problem is that certain keys
have the Mod2 modifier attached to them for no adequately explored reason.
The correct fix is to pass this file to xmodmap upon starting X:

        clear mod2
        keysym Multi_key = Alt_L
        add mod1 = Alt_L
        add mod1 = Alt_R

** The Compose key on a DEC keyboard does not work as Meta key.

This shell command should fix it:

  xmodmap -e 'keycode 0xb1 = Meta_L'

** When emacs starts up, I get lots of warnings about unknown keysyms.

If you are running the prebuilt binaries, the Motif library expects to find
certain thing in the XKeysymDB file.  This file is normally in /usr/lib/X11/
or in /usr/openwin/lib/.  If you keep yours in a different place, set the
environment variable $XKEYSYMDB to point to it before starting emacs.  If 
you still have the problem after doing that, perhaps your version of X is 
too old.  There is a copy of the MIT X11R5 XKeysymDB file in the emacs `etc'
directory.  Try using that one.

** My X resources used to work, and now some of them are being ignored.

Check the resources in .../etc/Emacs.ad (which is the same as the file
sample.Xdefaults).  Perhaps some of the default resources built in to 
emacs are now overriding your existing resources.  Copy and edit the
resources in Emacs.ad as necessary.

** I get complaints about the mapping of my HP keyboard at startup,
but I haven't changed anything.

The default HP keymap is set up to have Mod1 assigned to two different keys:
Meta_L and Mode_switch (even though there is not actually a Mode_switch key on
the keyboard -- it uses an "imaginary" keycode.)  There actually is a reason
for this, but it's not a good one.  The correct fix is to execute this command
upon starting X:

        xmodmap -e 'remove mod1 = Mode_switch'

** I have focus problems when I use `M-o' to switch to another screen
without using the mouse.

The focus issues with a program like XEmacs, which has multiple
homogeneous top-level windows, are very complicated, and as a result,
most window managers don't implement them correctly.

The R4/R5 version of twm (and all of its descendants) had buggy focus
handling.  Sufficiently recent versions of tvtwm have been fixed.  In
addition, if you're using twm, make sure you have not specified
"NoTitleFocus" in your .tvtwmrc file.  The very nature of this option
makes twm do some illegal focus tricks, even with the patch.

It is known that olwm and olvwm are buggy, and in different ways.  If
you're using click-to-type mode, try using point-to-type, or vice
versa.

In older versions of NCDwm, one could not even type at XEmacs windows.
This has been fixed in newer versions (2.4.3, and possibly earlier).

(Many people suggest that XEmacs should warp the mouse when focusing
on another screen in point-to-type mode.  This is not ICCCM-compliant
behavior.  Implementing such policy is the responsibility of the
window manager itself, it is not legal for a client to do this.)

** Emacs spontaneously displays "I-search: " at the bottom of the screen.

This means that Control-S/Control-Q (XON/XOFF) "flow control" is being
used.  C-s/C-q flow control is bad for Emacs editors because it takes
away C-s and C-q as user commands.  Since editors do not output long
streams of text without user commands, there is no need for a
user-issuable "stop output" command in an editor; therefore, a
properly designed flow control mechanism would transmit all possible
input characters without interference.  Designing such a mechanism is
easy, for a person with at least half a brain.

There are three possible reasons why flow control could be taking place:

  1) Terminal has not been told to disable flow control
  2) Insufficient padding for the terminal in use
  3) Some sort of terminal concentrator or line switch is responsible

First of all, many terminals have a set-up mode which controls whether
they generate XON/XOFF flow control characters.  This must be set to
"no XON/XOFF" in order for Emacs to work.  Sometimes there is an
escape sequence that the computer can send to turn flow control off
and on.  If so, perhaps the termcap `ti' string should turn flow
control off, and the `te' string should turn it on.

Once the terminal has been told "no flow control", you may find it
needs more padding.  The amount of padding Emacs sends is controlled
by the termcap entry for the terminal in use, and by the output baud
rate as known by the kernel.  The shell command `stty' will print
your output baud rate; `stty' with suitable arguments will set it if
it is wrong.  Setting to a higher speed causes increased padding.  If
the results are wrong for the correct speed, there is probably a
problem in the termcap entry.  You must speak to a local Unix wizard
to fix this.  Perhaps you are just using the wrong terminal type.

For terminals that lack a "no flow control" mode, sometimes just
giving lots of padding will prevent actual generation of flow control
codes.  You might as well try it.

If you are really unlucky, your terminal is connected to the computer
through a concentrator which sends XON/XOFF flow control to the
computer, or it insists on sending flow control itself no matter how
much padding you give it.  Unless you can figure out how to turn flow
control off on this concentrator (again, refer to your local wizard),
you are screwed!  You should have the terminal or concentrator
replaced with a properly designed one.  In the mean time, some drastic
measures can make Emacs semi-work.

You can make Emacs ignore C-s and C-q and let the operating system
handle them.  To do this on a per-session basis, just type M-x
enable-flow-control RET.  You will see a message that C-\ and C-^ are
now translated to C-s and C-q.  (Use the same command M-x
enable-flow-control to turn *off* this special mode.  It toggles flow
control handling.)

If C-\ and C-^ are inconvenient for you (for example, if one of them
is the escape character of your terminal concentrator), you can choose
other characters by setting the variables flow-control-c-s-replacement
and flow-control-c-q-replacement.  But choose carefully, since all
other control characters are already used by emacs.

IMPORTANT: if you type C-s by accident while flow control is enabled,
Emacs output will freeze, and you will have to remember to type C-q in
order to continue.

If you work in an environment where a majority of terminals of a
certain type are flow control hobbled, you can use the function
`enable-flow-control-on' to turn on this flow control avoidance scheme
automatically.  Here is an example:

(enable-flow-control-on "vt200" "vt300" "vt101" "vt131")

If this isn't quite correct (e.g. you have a mixture of flow-control hobbled
and good vt200 terminals), you can still run enable-flow-control
manually.

I have no intention of ever redesigning the Emacs command set for the
assumption that terminals use C-s/C-q flow control.  XON/XOFF flow
control technique is a bad design, and terminals that need it are bad
merchandise and should not be purchased.  Now that X is becoming
widespread, XON/XOFF seems to be on the way out.  If you can get some
use out of GNU Emacs on inferior terminals, more power to you, but I
will not make Emacs worse for properly designed systems for the sake
of inferior systems.

** Control-S and Control-Q commands are ignored completely.

For some reason, your system is using brain-damaged C-s/C-q flow
control despite Emacs's attempts to turn it off.  Perhaps your
terminal is connected to the computer through a concentrator
that wants to use flow control.

You should first try to tell the concentrator not to use flow control.
If you succeed in this, try making the terminal work without
flow control, as described in the preceding section.

If that line of approach is not successful, map some other characters
into C-s and C-q using keyboard-translate-table.  The example above
shows how to do this with C-^ and C-\.

** Control-S and Control-Q commands are ignored completely on a net
connection.

Some versions of rlogin (and possibly telnet) do not pass flow
control characters to the remote system to which they connect.
On such systems, emacs on the remote system cannot disable flow
control on the local system.

One way to cure this is to disable flow control on the local host
(the one running rlogin, not the one running rlogind) using the
stty command, before starting the rlogin process.  On many systems,
`stty start u stop u' will do this.

Some versions of tcsh will prevent even this from working.  One way
around this is to start another shell before starting rlogin, and
issue the stty command to disable flow control from that shell.

If none of these methods work, the best solution is to type
`M-x enable-flow-control' at the beginning of your emacs session, or
if you expect the problem to continue, add a line such as the
following to your .emacs (on the host running rlogind):

(enable-flow-control-on "vt200" "vt300" "vt101" "vt131")

See the entry about spontaneous display of I-search (above) for more
info.

** TTY redisplay is slow.

XEmacs has fairly new TTY redisplay support (beginning from 19.12),
which doesn't include some basic TTY optimizations -- like using
scrolling regions to move around blocks of text.  This is why
redisplay on the traditional terminals, or over slow lines can be very 
slow.

If you are interested in fixing this, please let us know at
<xemacs@xemacs.org>.

** Screen is updated wrong, but only on one kind of terminal.

This could mean that the termcap entry you are using for that terminal
is wrong, or it could mean that Emacs has a bug handing the
combination of features specified for that terminal.

The first step in tracking this down is to record what characters
Emacs is sending to the terminal.  Execute the Lisp expression
(open-termscript "./emacs-script") to make Emacs write all terminal
output into the file ~/emacs-script as well; then do what makes the
screen update wrong, and look at the file and decode the characters
using the manual for the terminal.  There are several possibilities:

1) The characters sent are correct, according to the terminal manual.

In this case, there is no obvious bug in Emacs, and most likely you
need more padding, or possibly the terminal manual is wrong.

2) The characters sent are incorrect, due to an obscure aspect of the
   terminal behavior not described in an obvious way by termcap.

This case is hard.  It will be necessary to think of a way for Emacs
to distinguish between terminals with this kind of behavior and other
terminals that behave subtly differently but are classified the same
by termcap; or else find an algorithm for Emacs to use that avoids the
difference.  Such changes must be tested on many kinds of terminals.

3) The termcap entry is wrong.

See the file etc/TERMS for information on changes that are known to be
needed in commonly used termcap entries for certain terminals.

4) The characters sent are incorrect, and clearly cannot be right for
   any terminal with the termcap entry you were using.

This is unambiguously an Emacs bug, and can probably be fixed in
termcap.c, terminfo.c, tparam.c, cm.c, redisplay-tty.c,
redisplay-output.c, or redisplay.c.

** Your Delete key sends a Backspace to the terminal, using an AIXterm.

The solution is to include in your .Xdefaults the lines:

   *aixterm.Translations: #override <Key>BackSpace: string(0x7f)
   aixterm*ttyModes: erase ^?

This makes your Backspace key send DEL (ASCII 127).

** With certain fonts, when the cursor appears on a character, the
character doesn't appear--you get a solid box instead.

One user on a Linux system reported that this problem went away with
installation of a new X server.  The failing server was XFree86 3.1.1.
XFree86 3.1.2 works.

** On SunOS 4.1.3, Emacs unpredictably crashes in _yp_dobind_soft.

This happens if you configure Emacs specifying just `sparc-sun-sunos4'
on a system that is version 4.1.3.  You must specify the precise
version number (or let configure figure out the configuration, which
it can do perfectly well for SunOS).

** On Irix, I don't see the toolbar icons and I'm getting lots of
entries in the warnings buffer.

SGI ships a really old Xpm library in /usr/lib which does not work at
all well with XEmacs.  The solution is to install your own copy of the
latest version of Xpm somewhere and then use the --site-includes and
--site-libraries flags to tell configure where to find it.

** On HPUX, you get "poll: Interrupted system call" message in the
window where XEmacs was launched.

Richard Cognot <cognot@ensg.u-nancy.fr> writes:

  I get a very strange problem when linking libc.a dynamically: every
  event (mouse, keyboard, expose...) results in a "poll: Interrupted
  system call" message in the window where XEmacs was
  launched. Forcing a static link of libc.a alone by adding
  /usr/lib/libc.a at the end of the link line solves this. Note that
  my 9.07 build of 19.14b17 and my (old) build of 19.13 both exhibit
  the same behaviour. I've tried various hpux patches to no avail. If
  this problem cannot be solved before the release date, binary kits
  for HP *must* be linked statically against libc, otherwise this
  problem will show up. (This is directed at whoever will volunteer
  for this kit, as I won't be available to do it, unless 19.14 gets
  delayed until mid-june ;-). I think this problem will be an FAQ soon
  after the release otherwise.

Note: The above entry is probably not valid for XEmacs 21.2 and
later.

** When Emacs tries to ring the bell, you get an error like

        audio: sst_open: SETQSIZE" Invalid argument
        audio: sst_close: SETREG MMR2, Invalid argument

you have probably compiled using an ANSI C compiler, but with non-ANSI
include files.  In particular, on Suns, the file
/usr/include/sun/audioio.h uses the _IOW macro to define the constant
AUDIOSETQSIZE.  _IOW in turn uses a K&R preprocessor feature that is
now explicitly forbidden in ANSI preprocessors, namely substitution
inside character constants.  All ANSI C compilers must provide a
workaround for this problem.  Lucid's C compiler is shipped with a new
set of system include files.  If you are using GCC, there is a script
called fixincludes that creates new versions of some system include
files that use this obsolete feature.

** My buffers are full of \000 characters or otherwise corrupt.

Some compilers have trouble with gmalloc.c and ralloc.c; try recompiling
without optimization.  If that doesn't work, try recompiling with
SYSTEM_MALLOC defined, and/or with REL_ALLOC undefined.

** On AIX 4, some programs fail when run in a Shell buffer
with an error message like No terminfo entry for "unknown".

On AIX, many terminal type definitions are not installed by default.
`unknown' is one of them.  Install the "Special Generic Terminal
Definitions" to make them defined.

** Emacs exits with "X protocol error" when run with an X server for
Windows.

A certain X server for Windows had a bug which caused this.
Supposedly the newer 32-bit version of this server doesn't have the
problem.

** A position you specified in .Xdefaults is ignored, using twm.

twm normally ignores "program-specified" positions.
You can tell it to obey them with this command in your `.twmrc' file:

  UsePPosition  "on"            #allow clents to request a position

** The right Alt key works wrong on German HP keyboards (and perhaps
   other non-English HP keyboards too).

This is because HPUX defines the modifiers wrong in X.  Here is a
shell script to fix the problem; be sure that it is run after VUE
configures the X server.

    xmodmap 2> /dev/null - << EOF
    keysym Alt_L = Meta_L
    keysym Alt_R = Meta_R
    EOF

    xmodmap - << EOF
    clear mod1
    keysym Mode_switch = NoSymbol
    add mod1 = Meta_L
    keysym Meta_R = Mode_switch
    add mod2 = Mode_switch
    EOF

** Trouble using ptys on IRIX, or running out of ptys.

The program mkpts (which may be in `/usr/adm' or `/usr/sbin') needs to
be set-UID to root, or non-root programs like Emacs will not be able
to allocate ptys reliably.

** Motif dialog boxes lose on Irix.

Larry Auton <lda@control.att.com> writes:
Beware of not specifying

        --with-dialogs=athena

if it builds with the motif dialogs [boom!] you're a dead man.

** Beware of the default image & graphics library on Irix

Richard Cognot <cognot@ensg.u-nancy.fr> writes:
You *have* to compile your own jpeg lib. The one delivered with SGI
systems is a C++ lib, which apparently XEmacs cannot cope with.

** Slow startup on Linux.

People using systems based on the Linux kernel sometimes report that
startup takes 10 to 15 seconds longer than `usual'.

This is because Emacs looks up the host name when it starts.
Normally, this takes negligible time; the extra delay is due to
improper system configuration.  This problem can occur for both
networked and non-networked machines.

Here is how to fix the configuration.  It requires being root.

*** Networked Case

First, make sure the files `/etc/hosts' and `/etc/host.conf' both
exist.  The first line in the `/etc/hosts' file should look like this
(replace HOSTNAME with your host name):

    127.0.0.1      localhost HOSTNAME

Also make sure that the `/etc/host.conf' files contains the following
lines:

    order hosts, bind 
    multi on

Any changes, permanent and temporary, to the host name should be
indicated in the `/etc/hosts' file, since it acts a limited local
database of addresses and names (e.g., some SLIP connections
dynamically allocate ip addresses).

*** Non-Networked Case

The solution described in the networked case applies here as well.
However, if you never intend to network your machine, you can use a
simpler solution: create an empty `/etc/host.conf' file.  The command
`touch /etc/host.conf' suffices to create the file.  The `/etc/hosts'
file is not necessary with this approach.

** On Solaris 2.4, Dired hangs and C-g does not work.  Or Emacs hangs
forever waiting for termination of a subprocess that is a zombie.

casper@fwi.uva.nl says the problem is in X11R6.  Rebuild libX11.so
after changing the file xc/config/cf/sunLib.tmpl.  Change the lines

    #if ThreadedX
    #define SharedX11Reqs -lthread
    #endif

to:

    #if OSMinorVersion < 4
    #if ThreadedX
    #define SharedX11Reqs -lthread
    #endif
    #endif

Be sure also to edit x/config/cf/sun.cf so that OSMinorVersion is 4
(as it should be for Solaris 2.4).  The file has three definitions for
OSMinorVersion: the first is for x86, the second for SPARC under
Solaris, and the third for SunOS 4.  Make sure to update the
definition for your type of machine and system.

Then do `make Everything' in the top directory of X11R6, to rebuild
the makefiles and rebuild X.  The X built this way work only on
Solaris 2.4, not on 2.3.

For multithreaded X to work it necessary to install patch
101925-02 to fix problems in header files [2.4].  You need
to reinstall gcc or re-run just-fixinc after installing that
patch.

However, Frank Rust <frust@iti.cs.tu-bs.de> used a simpler solution:
he changed
    #define ThreadedX          YES
to
    #define ThreadedX          NO
in sun.cf and did `make World' to rebuild X11R6.  Removing all
`-DXTHREAD*' flags and `-lthread' entries from lib/X11/Makefile and
typing 'make install' in that directory also seemed to work.

** With M-x enable-flow-control, you need to type C-\ twice to do
incremental search--a single C-\ gets no response.

This has been traced to communicating with your machine via kermit,
with C-\ as the kermit escape character.  One solution is to use
another escape character in kermit.  One user did

   set escape-character 17

in his .kermrc file, to make C-q the kermit escape character.

** The Motif version of Emacs paints the screen a solid color.

This has been observed to result from the following X resource:

   Emacs*default.attributeFont: -*-courier-medium-r-*-*-*-140-*-*-*-*-iso8859-*

That the resource has this effect indicates a bug in something, but we
do not yet know what.  If it is an Emacs bug, we hope someone can
explain what the bug is so we can fix it.  In the mean time, removing
the resource prevents the problem.

** Regular expressions matching bugs on SCO systems.

On SCO, there are problems in regexp matching when Emacs is compiled
with the system compiler.  The compiler version is "Microsoft C
version 6", SCO 4.2.0h Dev Sys Maintenance Supplement 01/06/93; Quick
C Compiler Version 1.00.46 (Beta).  The solution is to compile with
GCC.

** In Shell mode, you get a ^M at the end of every line.

This happens to people who use tcsh, because it is trying to be too
smart.  It sees that the Shell uses terminal type `unknown' and turns
on the flag to output ^M at the end of each line.  You can fix the
problem by adding this to your .cshrc file:

    if ($?EMACS) then
        if ($EMACS == "t") then
            unset edit 
            stty  -icrnl -onlcr -echo susp ^Z
        endif
    endif

** An error message such as `X protocol error: BadMatch (invalid
parameter attributes) on protocol request 93'.

This comes from having an invalid X resource, such as
   emacs*Cursor:   black
(which is invalid because it specifies a color name for something
that isn't a color.)

The fix is to correct your X resources.

** Mail is lost when sent to local aliases.

Many emacs mail user agents (VM and rmail, for instance) use the
sendmail.el library.  This library can arrange for mail to be
delivered by passing messages to the /usr/lib/sendmail (usually)
program .  In doing so, it passes the '-t' flag to sendmail, which
means that the name of the recipient of the message is not on the
command line and, therefore, that sendmail must parse the message to
obtain the destination address.

There is a bug in the SunOS4.1.1 and SunOS4.1.3 versions of sendmail.
In short, when given the -t flag, the SunOS sendmail won't recognize
non-local (i.e. NIS) aliases.  It has been reported that the Solaris
2.x versions of sendmail do not have this bug.  For those using SunOS
4.1, the best fix is to install sendmail V8 or IDA sendmail (which
have other advantages over the regular sendmail as well).  At the time
of this writing, these official versions are available:

 Sendmail V8 on ftp.cs.berkeley.edu in /ucb/sendmail:
   sendmail.8.6.9.base.tar.Z (the base system source & documentation)
   sendmail.8.6.9.cf.tar.Z   (configuration files)
   sendmail.8.6.9.misc.tar.Z (miscellaneous support programs)
   sendmail.8.6.9.xdoc.tar.Z (extended documentation, with postscript)

 IDA sendmail on vixen.cso.uiuc.edu in /pub:
   sendmail-5.67b+IDA-1.5.tar.gz

** On AIX, you get this message when running Emacs:

    Could not load program emacs
    Symbol smtcheckinit in csh is undefined
    Error was: Exec format error

or this one:

    Could not load program .emacs
    Symbol _system_con in csh is undefined
    Symbol _fp_trapsta in csh is undefined
    Error was: Exec format error

These can happen when you try to run on AIX 3.2.5 a program that was
compiled with 3.2.4.  The fix is to recompile.

** After running emacs once, subsequent invocations crash.

Some versions of SVR4 have a serious bug in the implementation of the
mmap () system call in the kernel; this causes emacs to run correctly
the first time, and then crash when run a second time.

Contact your vendor and ask for the mmap bug fix; in the mean time,
you may be able to work around the problem by adding a line to your
operating system description file (whose name is reported by the
configure script) that reads:
#define SYSTEM_MALLOC
This makes Emacs use memory less efficiently, but seems to work around
the kernel bug.

** Inability to send an Alt-modified key, when Emacs is communicating
directly with an X server.

If you have tried to bind an Alt-modified key as a command, and it
does not work to type the command, the first thing you should check is
whether the key is getting through to Emacs.  To do this, type C-h c
followed by the Alt-modified key.  C-h c should say what kind of event
it read.  If it says it read an Alt-modified key, then make sure you
have made the key binding correctly.

If C-h c reports an event that doesn't have the Alt modifier, it may
be because your X server has no key for the Alt modifier.  The X
server that comes from MIT does not set up the Alt modifier by
default.

If your keyboard has keys named Alt, you can enable them as follows:

    xmodmap -e 'add mod2 = Alt_L'
    xmodmap -e 'add mod2 = Alt_R'

If the keyboard has just one key named Alt, then only one of those
commands is needed.  The modifier `mod2' is a reasonable choice if you
are using an unmodified MIT version of X.  Otherwise, choose any
modifier bit not otherwise used.

If your keyboard does not have keys named Alt, you can use some other
keys.  Use the keysym command in xmodmap to turn a function key (or
some other 'spare' key) into Alt_L or into Alt_R, and then use the
commands show above to make them modifier keys.

Note that if you have Alt keys but no Meta keys, Emacs translates Alt
into Meta.  This is because of the great importance of Meta in Emacs.

** `Pid xxx killed due to text modification or page I/O error'

On HP/UX, you can get that error when the Emacs executable is on an NFS
file system.  HP/UX responds this way if it tries to swap in a page and
does not get a response from the server within a timeout whose default
value is just ten seconds.

If this happens to you, extend the timeout period.

** `expand-file-name' fails to work on any but the machine you dumped
Emacs on.

On Ultrix, if you use any of the functions which look up information
in the passwd database before dumping Emacs (say, by using
expand-file-name in site-init.el), then those functions will not work
in the dumped Emacs on any host but the one Emacs was dumped on.

The solution?  Don't use expand-file-name in site-init.el, or in
anything it loads.  Yuck - some solution.

I'm not sure why this happens; if you can find out exactly what is
going on, and perhaps find a fix or a workaround, please let us know.
Perhaps the YP functions cache some information, the cache is included
in the dumped Emacs, and is then inaccurate on any other host.

** Emacs fails to understand most Internet host names, even though
the names work properly with other programs on the same system.
  Emacs won't work with X-windows if the value of DISPLAY is HOSTNAME:0.
  Gnus can't make contact with the specified host for nntp.

This typically happens on Suns and other systems that use shared
libraries.  The cause is that the site has installed a version of the
shared library which uses a name server--but has not installed a
similar version of the unshared library which Emacs uses.

The result is that most programs, using the shared library, work with
the nameserver, but Emacs does not.

The fix is to install an unshared library that corresponds to what you
installed in the shared library, and then relink Emacs.

On SunOS 4.1, simply define HAVE_RES_INIT.

If you have already installed the name resolver in the file libresolv.a,
then you need to compile Emacs to use that library.  The easiest way to
do this is to add to config.h a definition of LIBS_SYSTEM, LIBS_MACHINE
or LIB_STANDARD which uses -lresolv.  Watch out!  If you redefine a macro
that is already in use in your configuration to supply some other libraries,
be careful not to lose the others.

Thus, you could start by adding this to config.h:

#define LIBS_SYSTEM -lresolv

Then if this gives you an error for redefining a macro, and you see that
the s- file defines LIBS_SYSTEM as -lfoo -lbar, you could change config.h
again to say this:

#define LIBS_SYSTEM -lresolv -lfoo -lbar

** Trouble using ptys on AIX.

People often install the pty devices on AIX incorrectly.
Use `smit pty' to reinstall them properly.

** Shell mode on HP/UX gives the message, "`tty`: Ambiguous".

christos@theory.tn.cornell.edu says:

The problem is that in your .cshrc you have something that tries to
execute `tty`. If you are not running the shell on a real tty then tty
will print "not a tty". Csh expects one word in some places, but tty
is giving it back 3.

The solution is to add a pair of quotes around `tty` to make it a
single word:

if (`tty` == "/dev/console") 

should be changed to:

if ("`tty`" == "/dev/console") 

Even better, move things that set up terminal sections out of .cshrc
and into .login.

** With process-connection-type set to t, each line of subprocess
output is terminated with a ^M, making ange-ftp and GNUS not work.

On SunOS systems, this problem has been seen to be a result of an
incomplete installation of gcc 2.2 which allowed some non-ANSI
compatible include files into the compilation.  In particular this
affected virtually all ioctl() calls.

** Once you pull down a menu from the menubar, it won't go away.

It has been claimed that this is caused by a bug in certain very old
(1990?)  versions of the twm window manager.  It doesn't happen with
recent vintages, or with other window managers.

** Emacs ignores the "help" key when running OLWM.

OLWM grabs the help key, and retransmits it to the appropriate client
using XSendEvent.  Allowing emacs to react to synthetic events is a
security hole, so this is turned off by default.  You can enable it by
setting the variable x-allow-sendevents to t.  You can also cause fix
this by telling OLWM to not grab the help key, with the null binding
"OpenWindows.KeyboardCommand.Help:".

** Programs running under terminal emulator do not recognize `emacs'
terminal type.

The cause of this is a shell startup file that sets the TERMCAP
environment variable.  The terminal emulator uses that variable to
provide the information on the special terminal type that Emacs
emulates.

Rewrite your shell startup file so that it does not change TERMCAP
in such a case.  You could use the following conditional which sets
it only if it is undefined.

    if ( ! ${?TERMCAP} ) setenv TERMCAP ~/my-termcap-file

Or you could set TERMCAP only when you set TERM--which should not
happen in a non-login shell.


* Compatibility problems (with Emacs 18, GNU Emacs, or previous XEmacs/lemacs)
==============================================================================

** "Symbol's value as variable is void: unread-command-char".
 "Wrong type argument: arrayp, #<keymap 143 entries>"
 "Wrong type argument: stringp, [#<keypress-event return>]"

There are a few incompatible changes in XEmacs, and these are the
symptoms.  Some of the emacs-lisp code you are running needs to be
updated to be compatible with XEmacs.

The code should not treat keymaps as arrays (use `define-key', etc.),
should not use obsolete variables like `unread-command-char' (use
`unread-command-events').  Many (most) of the new ways of doing things
are compatible in GNU Emacs and XEmacs.

Modern Emacs packages (Gnus, VM, W3, efs, etc) are written to support
GNU Emacs and XEmacs.  We have provided modified versions of several
popular emacs packages (dired, etc) which are compatible with this
version of emacs.  Check to make sure you have not set your load-path
so that your private copies of these packages are being found before
the versions in the lisp directory.

Make sure that your load-path and your $EMACSLOADPATH environment
variable are not pointing at an Emacs18 lisp directory.  This will
cripple emacs.

** Some packages that worked before now cause the error
Wrong type argument: arrayp, #<face ... >

Code which uses the `face' accessor functions must be recompiled with
xemacs 19.9 or later.  The functions whose callers must be recompiled
are: face-font, face-foreground, face-background,
face-background-pixmap, and face-underline-p.  The .elc files
generated by version 19.9 will work in 19.6 and 19.8, but older .elc
files which contain calls to these functions will not work in 19.9.

** Signaling: (error "Byte code stack underflow (byte compiler bug), pc 38")

This error is given when XEmacs 20 is compiled without MULE support
but is attempting to load a .elc which requires MULE support.  The fix
is to rebytecompile the offending file.

** Signaling: (wrong-type-argument ...) when loading mail-abbrevs

The is seen when installing the Insidious Big Brother Data Base (bbdb)
which includes an outdated copy of mail-abbrevs.el.  Remove the copy
that comes with bbdb and use the one that comes with XEmacs.


* MULE issues
=============

** A reminder: XEmacs/Mule work does not currently receive *any*
funding, and all work is done by volunteers.  If you think you can
help, please contact the XEmacs maintainers.

** XEmacs/Mule doesn't support TTY's satisfactorily.

This is a major problem, which we plan to address in a future release
of XEmacs.  Basically, XEmacs should have primitives to be told
whether the terminal can handle international output, and which
locale.  Also, it should be able to do approximations of characters to
the nearest supported by the locale.

** Internationalized (Asian) Isearch doesn't work.

Currently, Isearch doesn't directly support any of the input methods
that are not XIM based (like egg, canna and quail) (and there are
potential problems with XIM version too...).  If you're using egg
there is a workaround.  Hitting <RET> right after C-s to invoke
Isearch will put Isearch in string mode, where a complete string can
be typed into the minibuffer and then processed by Isearch afterwards.
Since egg is now supported in the minibuffer using string mode you can
now use egg to input your Japanese, Korean or Chinese string, then hit
return to send that to Isearch and then use standard Isearch commands
from there.

** Using egg and mousing around while in 'fence' mode screws up my
buffer.

Don't do this. The fence modes of egg and canna are currently very
modal, and messing with where they expect point to be and what they
think is the current buffer is just asking for trouble. If you're
lucky they will realize that something is awry, and simply delete the
fence, but worst case can trash other buffers too. We've tried to
protect against this where we can, but there still are many ways to
shoot yourself in the foot. So just finish what you are typing into
the fence before reaching for the mouse.

** Not all languages in Quail are supported like Devanagari and Indian
languages, Lao and Tibetan.

Quail requires more work and testing.  Although it has been ported to
XEmacs, it works really well for Japanese and for the European
languages.

** Right-to-left mode is not yet implemented, so languages like
Arabic, Hebrew and Thai don't work.

Getting this right requires more work.  It may be implemented in a
future XEmacs version, but don't hold your breath.  If you know
someone who is ready to implement this, please let us know.

** We need more developers and native language testers.  It's extremely
difficult (and not particularly productive) to address languages that
nobody is using and testing.

** The kWnn and cWnn support for Chinese and Korean needs developers
and testers.  It probably doesn't work.

** There are no `native XEmacs' TUTORIALs for any Asian languages,
including Japanese.  FSF Emacs and XEmacs tutorials are quite similar, 
so it should be sufficient to skim through the differences and apply
them to the Japanese version.

** We only have localized menus translated for Japanese, and the
Japanese menus are developing bitrot (the Mule menu appears in
English).

** XIM is untested for any language other than Japanese.