ncurses 6.2 - patch 20200831

[ncurses.git] / ANNOUNCE

                            Announcing ncurses 6.2

Overview

   The  ncurses  (new  curses)  library  is  a free software emulation of
   curses  in  System  V  Release  4.0 (SVr4), and more. It uses terminfo
   format,  supports  pads  and  color  and multiple highlights and forms
   characters and function-key mapping, and has all the other SVr4-curses
   enhancements  over  BSD curses. SVr4 curses became the basis of X/Open
   Curses.

   In  mid-June  1995,  the  maintainer of 4.4BSD curses declared that he
   considered  4.4BSD curses obsolete, and encouraged the keepers of unix
   releases such as BSD/OS, FreeBSD and NetBSD to switch over to ncurses.

   Since 1995, ncurses has been ported to many systems:
     * It is used in almost every system based on the Linux kernel (aside
       from some embedded applications).
     * It  is  used  as the system curses library on OpenBSD, FreeBSD and
       MacOS.
     * It  is used in environments such as Cygwin and MinGW. The first of
       these was EMX on OS/2 Warp.
     * It is used (though usually not as the system curses) on all of the
       vendor  unix  systems,  e.g.,  AIX,  HP-UX,  IRIX64, SCO, Solaris,
       Tru64.
     * It should work readily on any ANSI/POSIX-conforming unix.

   The distribution includes the library and support utilities, including
     * captoinfo, a termcap conversion tool
     * clear, utility for clearing the screen
     * infocmp, the terminfo decompiler
     * tabs, set tabs on a terminal
     * tic, the terminfo compiler
     * toe, list (table of) terminfo entries
     * tput,  utility  for  retrieving  terminal  capabilities  in  shell
       scripts
     * tset, to initialize the terminal

   Full manual pages are provided for the library and tools.

   The ncurses distribution is available at ncurses' homepage:

     ftp://ftp.invisible-island.net/ncurses/ or
     https://invisible-mirror.net/archives/ncurses/ .

   It is also available via anonymous FTP at the GNU distribution site

     ftp://ftp.gnu.org/gnu/ncurses/ .

Release Notes

   These notes are for ncurses 6.2, released February 12, 2020.

   This  release  is  designed  to  be source-compatible with ncurses 5.0
   through  6.1; providing extensions to the application binary interface
   (ABI).  Although  the  source  can  still be configured to support the
   ncurses  5  ABI, the reason for the release is to reflect improvements
   to the ncurses 6 ABI and the supporting utility programs.

   There  are,  of  course,  numerous  other improvements, listed in this
   announcement.

   The  most  important  bug-fixes/improvements  dealt  with user-defined
   capabilities  in terminal descriptions. The release notes also mention
   some other bug-fixes, but are focused on new features and improvements
   to existing features since ncurses 6.1 release.

  Library improvements

    New features

   There are several new features:
     * O_EDGE_INSERT_STAY  tells  the  form  library  to optionally delay
       cursor movement on a field edge/boundary
     * O_INPUT_FIELD  extension to form library allows a dynamic field to
       shrink if the new limit is smaller than the current field size.
     * added  exit_curses  and  exit_terminfo to replace internal symbols
       for leak-checking.
     * added curses_trace, to replace trace().

   Additionally,  to  improve  performance other changes (and extensions)
   are provided in this release:
     * mouse  decoding  now handles shift/control/alt logic when decoding
       xterm's 1006 mode
     * ncurses  now  defines a limit for wgetnstr, wgetn_wstr when length
       is negative or "too large".
     * reordered  loop-limit checks in winsnstr in case the string has no
       terminating null and only the number of characters is used.
     * there  is  now  no  buffer-size  limit  when  reading the $TERMCAP
       variable.
     * the  $TERMCAP  variable  may  be  interpreted  as  a fallback to a
       terminfo entry
     * mvcur  now decides whether to use hard-tabs, using xt, tbc and hts
       as clues.
     * extended  colors  are  improved  by  modifying an internal call to
       vid_puts  to pass extended color pairs e.g., from tty_update.c and
       lib_mvcur.c
     * the  initialization  functions  now  avoid relying upon persistent
       data for the result from getenv
     * scrolling is improved:
          + a limit check in newline_forces_scroll handles the case where
            the row is inside scroll-margins, but not at the end.
          + improved loop limits in _nc_scroll_window handle a case where
            the scrolled data is a pad which is taller than the window.

    Other improvements

   These are revised features:
     * used  "const"  in  some prototypes rather than NCURSES_CONST where
       X/Open  Curses  was updated to do this, e.g., wscanw, newterm, the
       terminfo  interface.  Also  use  "const"  for  consistency  in the
       termcap interface, which was withdrawn by X/Open Curses in Issue 5
       (2007).  As  of  Issue  7,  X/Open  Curses still lacks "const" for
       certain return values, e.g., keyname.
     * modified  wbkgd  and  wbkgrnd  to  improve compatibility with SVr4
       curses,  changing the way the window rendition is updated when the
       background character is modified
     * improved  terminfo  write/read by modifying the fourth item of the
       extended  header  to  denote  the  number  of valid strings in the
       extended string table (see term(5)).
     * modified   the   initialization  checks  for  mouse  so  that  the
       xterm+sm+1006  block  will  work  with  terminal  descriptions not
       mentioning xterm.

   These were done to limit or ultimately deprecate features:
     * deprecated  safe-sprintf, since the vsnprintf function, which does
       what was needed, was standardized long ago.
     * marked   vwprintw  and  vwscanw  as  deprecated;  recommend  using
       vw_printw and vw_scanw, respectively.
     * added  deprecation warnings for internal functions called by older
       versions of tack.
     * removed unused _nc_import_termtype2 function.

   These are improvements to existing features:
     * check parameter of set_escdelay, return ERR if negative.
     * check  parameter  of  set_tabsize,  return ERR if not greater than
       zero
     * correct  a status-check in _nc_read_tic_entry() so that if reading
       a hex/b64 $TERMINFO, and the $TERM does not match, fall-through to
       the compiled-in search list.
     * amend check for repeat_char to handle a case where setlocale() was
       called after initscr
     * move macro for is_linetouched inside NCURSES_NOMACROS ifndef.
     * use _nc_copy_termtype2 rather than direct assignment in setupterm,
       in   case   it   is  called  repeatedly  using  fallback  terminfo
       descriptions
     * improve   workaround   for  Solaris  wcwidth  versus  line-drawing
       characters
     * add  checks  in repair_subwindows to keep the current position and
       scroll-margins inside the resized subwindow.
     * correct  a  buffer-limit  in  write_entry.c  for  systems that use
       caseless filenames.
     * improved build-time utility report_offsets:
          + add categories, e.g., "w" for wide-character, "t" for threads
            to  make the report more readable. Reorganized the structures
            reported to make the categories more apparent.
          + add  NCURSES_GLOBALS  and NCURSES_PRESCREEN to report to show
            how similar the different libtinfo configurations are.
     * modified  some header files to ensure that those include necessary
       files except for the previously-documented cases
     * added  some  traces  in  initialization to show whether a fallback
       entry is used.
     * made minor optimization to reduce calls to _nc_reserve_pairs

   These are corrections to existing features:
     * fix  a  special  case  in  PutAttrChar  where  a cell is marked as
       alternate-character  set,  but  the  terminal  does  not  actually
       support the given graphic character. This would happen in an older
       terminal such as vt52, which lacks most line-drawing capability.
     * corrected  flag  for "seq" method of db 1.8.5 interface, needed by
       toe on some of the BSDs.
     * modify  comparison  in  make_hash.c  to  correct a special case in
       collision handling for Caps-hpux11
     * add    extended_slk_color{,_sp}   symbols   to   the   appropriate
       package/*.{map,sym} files
     * modify  lib_setup  to  avoid  calling pthread_self() without first
       verifying that the address is valid, i.e., for weak symbols
     * add  a  couple  of  broken-linker symbols to the list of versioned
       symbols to help with link-time optimization versus weak symbols.

  Program improvements

   Several improvements were made to the utility programs:

   clear

          + improved  logic  for  clearing with the E3 extension, in case
            the  terminal  scrolls  content  onto  its saved-lines before
            actually  clearing  the  display, by clearing the saved-lines
            after clearing the display

   infocmp

          + omit  filtering  of  "OTxx" names which are used for obsolete
            capabilities,  when  the output is sorted by long-names. This
            change helps when making a table of the short/long capability
            names.

   tic

          + added   check   for   consistent   alternate   character  set
            capabilities.
          + added check for paired indn/rin.
          + added check for terminals with parm_dch vs parm_ich.
          + added  check  for  the  case  where setf/setb are given using
            different   strings,   but   provide   identical  results  to
            setaf/setab.
          + corrected check for ich1.
          + changed  a  too-large  terminal entry from a fatal error to a
            warning.

   toe

          + ignores  any  hex/b64 $TERMINFO value in the list of terminfo
            databases.

   tset

          + replace  check  in reset command for obsolete "pt" capability
            using tbc and hts capabilities as clues
          + modify reset to allow for tabstops at intervals other than 8.
          + change   reset's   behavior   for  margins  to  simply  clear
            soft-margins  if  possible,  rather  than  clearing  and then
            setting them according to the terminal's width.

   tput

          + add "x" to getopt string so that "tput -x clear" works.

   Several  changes were made to the generated ncurses*config scripts and
   the   analogous   ".pc"   files  to  reduce  differences  between  the
   configurations they report:
     * modified the ncurse*-config and pc-files to more closely match for
       the -I and -l options.
     * filtered out linker-specs from the --libs report.
     * amended  the ncurses*-config and pc-files to take into account the
       rpath hack which differed between those files.
     * modified  generated  ncurses*config  and  ncurses.pc, ncursesw.pc,
       etc., to list helper libraries such as gpm for static linking.

    Examples

   Along  with  the  library and utilities, improvements were made to the
   ncurses-examples.  Most  of  this  activity  aimed  at  improving  the
   test-packages.  A few changes are more generally useful, e.g., for the
   main   ncurses  test-program,  and  for  analyzing  traces  using  the
   tracemunch script:
     * improve  recovery  from  error  when  reading command-character in
       test/ncurses.c, showing the relevant error message and not exiting
       on EINTR.
     * improve  tracemunch,  by keeping track of TERMINAL* values, and if
       tracing  was first turned on after initialization, attempt to show
       distinct screen, window and terminal names anyway.
     * modify tracemunch to accept filename parameters in addition to use
       as a pipe/filter.
     * update  tracemunch  to  work  with  perl 5.26.2, which changed the
       rules for escaping regular expressions.
     * add some checks in tracemunch for undefined variables.
     * modify TurnOn/TurnOff macros (in lib_vidattr.c and lib_vid_attr.c)
       to avoid expansion of "CUR" in trace.

   There are other new demo/test programs and reusable examples:

   color_content
          Demonstrate   the   color_content   and  extended_color_content
          functions.

   demo_tabs
          A simple demo of tabs in curses.

   dump_window
          A  portable  curses screen-dump, used to compare ncurses screen
          contents with Solaris.

   pair_content
          Demonstrate    the   pair_content   and   extended_pair_content
          functions.

   report_hashing
          Check hash-tables used for terminfo and termcap names.

   parse_rgb
          Sample   implementation  of  the  ncurses  RGB  extension  from
          user_caps.5, used in picsmap and savescreen programs.

   A  variety  of  improvements  were made to existing programs, both new
   features  as  well  as  options added to make the set of programs more
   consistent.
     * add  "-l"  option to test/background, to dump screen contents in a
       form that lets different curses implementations be compared.
     * add  "@"  command  to  test/ncurses F-test, to allow rapid jump to
       different character pages.
     * added enum, regex examples to test/demo_forms
     * amend  Scaled256() macro in test/picsmap.c to cover the full range
       0..1000
     * corrected  pathname used in Ada95 sample programs for explain.txt,
       to  work  with  test-packages, and used an awk script to split the
       resulting pathname when it would be too long for a single line.
     * ignore  interrupted  system-call  in  test/ncurses's command-line,
       e.g., if the terminal were resized.
     * improved  ifdef's  for  TABSIZE  variable,  to  help with AIX/HPUX
       ports.

  Terminal database

   There are several new terminal descriptions:

     alacritty,  domterm,  kitty,  mintty,  mintty-direct,  ms-terminal,
     n7900,   nsterm-build309,  nsterm-direct,  screen5,  ti703,  ti707,
     ti703-w, ti707-w vscode, vscode-direct, xterm-mono, xterm.js

   There  are  many  changes to existing terminal descriptions. Some were
   updates to several descriptions:
     * use ansi+rep in a dozen places
     * add rs1 to konsole, mlterm
     * improve several flash capabilities with trailing mandatory delays
     * drop   ich1   from   rxvt-basic,   Eterm  and  mlterm  to  improve
       compatibility with old non-curses programs
     * add/use xterm+keypad in xterm-new
     * use xterm+sl-twm for consistency, nine places
     * improve xm example in xterm+x11mouse and xterm+sm_1006.

   while  others  affected specific descriptions. These were retested, to
   take into account changes by their developers:

     terminator, st

   while  these are specific fixes based on reviewing documentation, user
   reports, or warnings from tic:

   adds200:

          + fix typo

   gnome-256color

          + base entry on "gnome", not "vte", for consistency

   interix

          + trim unnecessary setf/setb

   linux-16color

          + accommodate  Linux  console driver incompatibility introduced
            in early 2018

   nsterm-256color:

          + add nsterm-build309 to replace nsterm-256color, assigning the
            latter  as  an  alias  of  nsterm,  to  make  mouse work with
            nsterm-256color

   regent40:

          + renumber function-keys to match manual

   regent60:

          + add cd (clr_eos)
          + corrected acsc
          + add shifted function-keys

   tvi950:

          + added  function-key  definitions  to agree with Televideo 950
            manual
          + corrected acsc
          + remove bogus kf0
          + add bel

   tvi955:

          + fix typo

   vi200:

          + add acsc string, including right/down-arrow

   wy50:

          + corrected acsc

   wy50 and wy60:

          + add shifted function-keys as kF1 to kF16

   xterm+x11hilite:

          + eliminate unused p5 parameter.

   A few entries use extensions (user-defined terminal capabilities):
     * use  xterm+sm+1006  (aka  "SGR  1006  mouse") for konsole-base and
       putty
     * add Smol/Rmol user-defined capability to tmux and vte-2018
     * add Smulx user-defined capability to tmux, vte-2018

  Documentation

   As usual, this release
     * improves documentation by describing new features,
     * attempts  to  improve the description of features which users have
       found confusing
     * fills  in overlooked descriptions of features which were described
       in the NEWS file but treated sketchily in manual pages.

   In  addition  to  providing  background  information  to explain these
   features   and   show   how   they  evolved,  there  are  corrections,
   clarifications, etc.:
     * Corrections:
          + correct  error-returns  listed in manual pages for a few form
            functions
          + corrected  prototypes  in  several  manpages  using script to
            extract those in compilable form.
          + fix typo in term.5, improve explanation of format
     * Clarify in manual pages that vwprintw and vwscanw are obsolete.
       They have not been part of X/Open Curses since 2007.
     * New/improved history and portability sections:
          + curs_addch.3x gives some background for ACS symbols.
          + curs_getcchar.3x  explains  a  difference between ncurses and
            X/Open Curses.
          + curs_getstr.3x  gives  historical/portability  background for
            the length parameter of wgetnstr.
          + curs_slk.3x  lists  a few differences between SVr4 curses and
            X/Open Curses for soft-keys.
          + curs_terminfo.3x  explains that the initial implementation of
            terminfo  in  SVr2 was mostly replaced by other developers in
            SVr3.
          + infocmp.1  explains  that the initial version of terminfo had
            no  tool  for decompiling descriptions. That came later, with
            SVr3, with a different developer.
          + tabs.1 tells more than you wanted to know about the tool.
          + tic.1  explains  that  the  initial version of terminfo had a
            rudimentary  tool  (based  on termcap) for compiling entries.
            The tool used with Unix was developed by others for SVr3.
          + toe.1 explains the origin of this tool.
     * Improvements for user_caps.5:
          + mention meml, memu and box1
          + expanded description of XM
          + add a clarification regarding the RGB capability.
          + mention user_caps.5 in the tic and infocmp manual pages.
     * Other improvements:
          + curs_add_wch.3x  adds  note about Unicode terminology for the
            line-drawing characters.
          + curs_color.3x   improves  discussion  of  error  returns  and
            extensions.
          + curs_mouse.3x  explains how the kmous and XM capabilities are
            used for xterm-mouse input.
          + curs_refresh.3x  improves documentation regarding the virtual
            and physical screens.
          + curs_util.3x  mentions  a  difference between SVr4 and X/Open
            Curses for unctrl.h
          + curs_variables.3x   improves  description  of  the  init_tabs
            capability and TABSIZE variable.
          + ncurses.3x   improves  documentation  regarding  feature-test
            macros in curses.h
          + resizeterm.3x   about   top-level  windows  which  touch  the
            screen's borders.
          + tput.1 clarifies how tput determines the terminal size.

   There  are  no new manual pages (all of the manual page updates are to
   existing pages).

   Some  of  the  improvements  are  more subtle, relating to the way the
   information  is presented. For instance, the generated terminfo.5 file
   uses  a  different  table  layout,  allowing  it  to use space on wide
   terminals more effectively.

  Interesting bug-fixes

   While  there  were  many bugs fixed during development of ncurses 6.2,
   only  a  few  (the  reason  for  this release) were both important and
   interesting. Most of the bug-fixes were for local issues which did not
   affect  compatibility across releases. Since those are detailed in the
   NEWS file no elaboration is needed here.

   The  interesting  bugs  were in tic/infocmp's handling of user-defined
   capabilities.  These  were  not recent bugs. Initially it was a simple
   problem:
     * The  user-defined capabilities can be any type (boolean, number or
       string),  but  once given a type all uses of the name must conform
       to  that  type--unless  some  special  support  for  a  particular
       multi-typed name is built into ncurses.
     * One of simpleterm's contributors copied some definitions for using
       tmux's user-defined capabilities in late in 2016.

diff --git a/st.info b/st.info
@@ -185,7 +185,10 @@ st| simpleterm,
  tsl=\E]0;,
  xenl,
  vpa=\E[%i%p1%dd,
-
+# Tmux unofficial extensions, see TERMINFO EXTENSIONS in tmux(1)
+ Se,
+ Ss,
+ Tc,

 st-256color| simpleterm with 256 colors,
  use=st,

     * Later,  in (referring to a version from mid-2017), a user asked to
       have it updated in ncurses.
     * However,  it  had  an  error  from  the  change  in late 2016. The
       terminal description made what tmux expected to be string actually
       a boolean.
       Over  the  years,  there  were  problems with each of simpleterm's
       terminal  descriptions.  I  repaired those, and usually dealt with
       the problem.
     * The  difference  in this case was that when compiling the terminal
       database, tic may have in memory the definitions for more than one
       terminal  description  (so  that  it  can resolve "use=" clauses).
       Seeing   two  different  types  for  the  same  name,  in  certain
       situations  it  would  incorrectly merge the symbol tables for the
       two terminal descriptions.
     * On  simpleterm's  side,  their bug was finally fixed in late 2019,
       three years after the bug was created.

   For  ncurses,  the  elapsed  time  to fix this bug was less than three
   years.  Someone reported a problem with the terminal description a few
   weeks  after  releasing  ncurses 6.1 (in tmux #1264), and the terminal
   description was updated that week (ncurses patch 20180224):

20180224
        + modify _nc_resolve_uses2() to detect incompatible types when merging
          a "use=" clause of extended capabilities.  The problem was seen in a
          defective terminfo integrated from simpleterm sources in 20171111,
          compounded by repair in 20180121.
        + correct Ss/Ms interchange in st-0.7 entry (tmux #1264) -TD

   The larger part of that change added a check to prevent a simple merge
   of  terminal  descriptions  where  the same user-defined name was used
   with different types. But it raised some questions:
     * Was  there  a  reliable  way to manage terminal descriptions which
       used the same extended name in different ways?
     * Should  ncurses  provide  a registry of well-known extended names,
       with their types?

   Since  the  correction to terminfo.src could have been readily adopted
   by  packagers,  there  was  nothing  more  to  be  done  from ncurses'
   standpoint  on that part. But improving ncurses to prevent issues like
   that is the reason for making a release.

   Nothing  more  (constructive) was mentioned with regard to simpleterm.
   But  a  few  problems  were  found  in  the  handling  of user-defined
   capabilities:
     * Forward-references to user-defined capabilities in a "use=" clause
       did  not  allocate  new  data  for  each  use.  In tic, successive
       compilation   of   terminal   entries   could   add   user-defined
       capabilities to the wrong terminal entry.
       This  was  not noticed before, since xterm's terminal descriptions
       were  the main users of the feature, and almost all of the uses of
       the building-blocks which contained user-defined capabilities were
       backward-references.
     * There  is  one  (documented)  case  where  ncurses  6.1 supports a
       user-defined  capability that could be any type (i.e., "RGB"). The
       check  added  in February 2018 to guard against mismatches did not
       handle all of the combinations needed.

   Both  of  these  issues  dated  from  the  original  implementation of
   user-defined  capabilities.  Fixing  them does not change the terminal
   database, but a older tic without the fixes will not be able to handle
   terminfo  sources  which rely upon those fixes. Starting in June 2019,
   the  download  link  for  the  terminfo source file was capped at that
   date. The development sources have an up-to-date copy of the file, for
   people with a legitimate need for it.

   The  "-c"  (check) option of tic is not very useful if it cannot offer
   advice on parameters needed for user-defined capabilities. The various
   Caps  files  were  reorganized to reduce redundancy, and in the common
   portion  (Caps-ncurses),  a  registry  of user-defined capabilities is
   provided for use by tic. While users can still define their own custom
   capabilities,  tic  will not offer any advice when their parameters do
   not match.

   In  ncurses  6.2, tic makes a special check to allow any type for RGB,
   but  its  being  able to do this relies upon fixes made in the ncurses
   library in mid-2019.

  Configuration changes

    Major changes

   There  are  no  major  changes. Several new options were added to ease
   integration  of packages with systems using different versions of GNAT
   and ncurses. Also, improvements were made to configure checks.

    Configuration options

   There are a few new/modified configure options:

   --with-config-suffix
          helps  work  around  a  filename  conflict with Debian packages
          versus test-packages.

   --with-ada-libname
          allows  one  to  rename  the  "AdaCurses" library (at least one
          packager prefers a lowercase name).

   --with-fallbacks
          now ensures there is a value, and adds the fallback information
          to top-level Makefile summary.

   --with-pcre2
          check for pcre-posix library to help with MinGW port.

   --with-tic-path and

   --with-infocmp-path
          help  work  around  problems  building  fallback  source  using
          pre-6.0 tic/infocmp.

   --with-versioned-syms
          option value can now be a relative pathname.

  Portability

   Many  of  the  portability  changes  are implemented via the configure
   script:
     * ignore $TERMINFO as a default value in configure script if it came
       from the infocmp -Q option.
     * distinguish  gcc  from  icc  and  clang when the --enable-warnings
       option   is   not   used,  to  avoid  unnecessary  warnings  about
       unrecognized inline options
     * consistently  prepend  new  libraries  as  they  are  found during
       configuration,  rather  than  relying  upon  the linker to resolve
       order dependencies of libraries.
     * modified  configure  scripts  to  reduce  relinking/ranlib  during
       library install :
          + use  "install -p" when available, to avoid need for ranlib of
            static libraries.
          + scripts which use "--disable-relink;" add a 1-second sleep to
            work around tools which use whole-second timestamps, e.g., in
            utime rather than the actual file system resolution.
     * add configure check for getenv to work around implementation shown
       in  Emscripten  which overwrites the previous return value on each
       call.
       Use  that  to optionally suppress START_TRACE macro, whose call to
       getenv may not work properly
     * change  target configure level for _XOPEN_SOURCE to 600 to address
       use of vsscanf and setenv.
     * reduce  use of _GNU_SOURCE for current glibc where _DEFAULT_SOURCE
       combines with _XOPEN_SOURCE
       Allow  for  Cygwin's  newlib when checking for the _DEFAULT_SOURCE
       symbol.
       MidnightBSD   is   now   checked   for  the  _XOPEN_SOURCE-related
       definitions.
     * If the check for va_copy or __va_copy fails,
          + configure  now  tries copying the pointers for va_list, or as
            an array.
          + alternatively, it checks for __builtin_va_copy(), which could
            be used with AIX xlc in c89 mode.
     * several changes to support a port to Ultrix 3.1:
          + check if "b" binary feature of fopen works
          + check for missing feature of locale.h
          + add fallback for strstr() in test-programs
          + add fallback for STDOUT_FILENO in test-programs
     * The test/configure script (used for ncurses-examples) is improved:
          + work around non-ncurses termcap.h file, e.g., in Slackware.
          + check for TABSIZE variable.
          + checks  for  the  X11/Intrinsic.h  header, accommodate recent
            MacOS changes which largely emptied /usr/include.

   Here are some of the other portability fixes:
     * added  dummy  "check"  rule  in  top-level  and  test-Makefile  to
       simplify building test-packages for ArchLinux.
     * dropped   library-dependency   on  psapi  for  MinGW  port,  since
       win_driver.c   defines   PSAPI_VERSION   to   2,   making  it  use
       GetProcessImageFileName from kernel32.dll
     * made  build-fixes  for  configuration  using --program-suffix with
       Ada95,  noticed  with  MacOS  but  applicable  to  other platforms
       without libpanelw, etc.
     * modified  ncurses/Makefile.in  to  fix a case where Debian/testing
       changes to the ld --as-needed configuration broke ncurses-examples
       test packages.
     * used   _WIN32/_WIN64   in  preference  to  __MINGW32__/__MINGW64__
       symbols  to simplify building with Microsoft Visual C++, since the
       former are defined in both compiler configurations.
     _________________________________________________________________

Features of ncurses

   The  ncurses  package  is  fully upward-compatible with SVr4 (System V
   Release 4) curses:
     * All of the SVr4 calls have been implemented (and are documented).
     * ncurses  supports  all  of  the for SVr4 curses features including
       keyboard  mapping,  color,  forms-drawing with ACS characters, and
       automatic recognition of keypad and function keys.
     * ncurses  provides  these SVr4 add-on libraries (not part of X/Open
       Curses):
          + the  panels  library,  supporting  a  stack  of  windows with
            backing store.
          + the   menus   library,  supporting  a  uniform  but  flexible
            interface for menu programming.
          + the   form   library,   supporting  data  collection  through
            on-screen forms.
     * ncurses's  terminal database is fully compatible with that used by
       SVr4 curses.
          + ncurses  supports user-defined capabilities which it can see,
            but  which are hidden from SVr4 curses applications using the
            same terminal database.
          + It  can  be optionally configured to match the format used in
            related systems such as AIX and Tru64.
          + Alternatively,  ncurses  can  be  configured  to  use  hashed
            databases  rather  than  the  directory of files used by SVr4
            curses.
     * The ncurses utilities have options to allow you to filter terminfo
       entries for use with less capable curses/terminfo versions such as
       the HP/UX and AIX ports.

   The ncurses package also has many useful extensions over SVr4:
     * The  API  is 8-bit clean and base-level conformant with the X/OPEN
       curses  specification, XSI curses (that is, it implements all BASE
       level  features,  and  most  EXTENDED  features). It includes many
       function calls not supported under SVr4 curses (but portability of
       all calls is documented so you can use the SVr4 subset only).
     * Unlike  SVr3 curses, ncurses can write to the rightmost-bottommost
       corner  of  the  screen  if  your terminal has an insert-character
       capability.
     * Ada95 and C++ bindings.
     * Support  for mouse event reporting with X Window xterm and FreeBSD
       and OS/2 console windows.
     * Extended mouse support via Alessandro Rubini's gpm package.
     * The  function  wresize  allows  you  to resize windows, preserving
       their data.
     * The  function  use_default_colors allows you to use the terminal's
       default colors for the default color pair, achieving the effect of
       transparent colors.
     * The functions keyok and define_key allow you to better control the
       use of function keys, e.g., disabling the ncurses KEY_MOUSE, or by
       defining  more  than  one  control  sequence to map to a given key
       code.
     * Support for 256-color terminals, such as modern xterm.
     * Support for 16-color terminals, such as aixterm and modern xterm.
     * Better  cursor-movement  optimization.  The package now features a
       cursor-local-movement computation more efficient than either BSD's
       or System V's.
     * Super   hardware   scrolling   support.   The  screen-update  code
       incorporates  a novel, simple, and cheap algorithm that enables it
       to  make  optimal  use  of hardware scrolling, line-insertion, and
       line-deletion  for  screen-line  movements. This algorithm is more
       powerful than the 4.4BSD curses quickch routine.
     * Real  support  for  terminals  with  the  magic-cookie glitch. The
       screen-update  code  will  refrain from drawing a highlight if the
       magic-   cookie  unattributed  spaces  required  just  before  the
       beginning  and  after the end would step on a non-space character.
       It  will  automatically  shift  highlight boundaries when doing so
       would  make it possible to draw the highlight without changing the
       visual appearance of the screen.
     * It  is  possible to generate the library with a list of pre-loaded
       fallback  entries linked to it so that it can serve those terminal
       types  even  when  no  terminfo tree or termcap file is accessible
       (this  may  be useful for support of screen-oriented programs that
       must run in single-user mode).
     * The tic/captoinfo utility provided with ncurses has the ability to
       translate  many  termcaps  from  the XENIX, IBM and AT&T extension
       sets.
     * A BSD-like tset utility is provided.
     * The ncurses library and utilities will automatically read terminfo
       entries  from  $HOME/.terminfo  if  it exists, and compile to that
       directory  if  it  exists  and the user has no write access to the
       system  directory.  This feature makes it easier for users to have
       personal  terminfo  entries without giving up access to the system
       terminfo directory.
     * You  may  specify  a  path  of  directories to search for compiled
       descriptions  with  the  environment  variable TERMINFO_DIRS (this
       generalizes  the  feature  provided by TERMINFO under stock System
       V.)
     * In  terminfo  source files, use capabilities may refer not just to
       other entries in the same source file (as in System V) but also to
       compiled  entries  in  either the system terminfo directory or the
       user's $HOME/.terminfo directory.
     * The  table-of-entries  utility  toe makes it easy for users to see
       exactly what terminal types are available on the system.
     * The library meets the XSI requirement that every macro entry point
       have  a  corresponding  function  which may be linked (and will be
       prototype-checked)  if  the  macro  definition  is  disabled  with
       #undef.
     * Extensive  documentation  is  provided (see the Additional Reading
       section of the ncurses FAQ for online documentation).

Applications using ncurses

   The  ncurses  distribution  includes  a  selection  of  test  programs
   (including   a   few   games).   These  are  available  separately  as
   ncurses-examples

   The   ncurses   library  has  been  tested  with  a  wide  variety  of
   applications including:

   aptitude
          FrontEnd to Apt, the debian package manager

          https://wiki.debian.org/Aptitude

   cdk
          Curses Development Kit

          https://invisible-island.net/cdk/

   ded
          directory-editor

          https://invisible-island.net/ded/

   dialog
          the  underlying  application used in Slackware's setup, and the
          basis   for  similar  install/configure  applications  on  many
          systems.

          https://invisible-island.net/dialog/

   lynx
          the text WWW browser

          https://lynx.invisible-island.net/

   mutt
          mail utility

          http://www.mutt.org/

   ncftp
          file-transfer utility

          https://www.ncftp.com/

   nvi
          New vi uses ncurses.

          https://sites.google.com/a/bostic.com/keithbostic/vi

   ranger
          A console file manager with VI key bindings in Python.

          https://ranger.github.io/

   tin
          newsreader, supporting color, MIME

          http://www.tin.org/

   vifm
          File manager with vi like keybindings

          https://vifm.info/

   as well as some that use ncurses for the terminfo support alone:

   minicom
          terminal emulator for serial modem connections

          https://alioth.debian.org/projects/minicom/

   mosh
          a replacement for ssh.

          https://mosh.mit.edu/

   tack
          terminfo action checker

          https://invisible-island.net/ncurses/tack.html

   tmux
          terminal multiplexor

          https://github.com/tmux/tmux/wiki

   vile
          vi-like-emacs  may  be  built  to  use the terminfo, termcap or
          curses interfaces.

          https://invisible-island.net/vile/

   and finally, those which use only the termcap interface:

   emacs
          text editor

          https://www.gnu.org/software/emacs/

   less
          The  most  commonly  used  pager  (a program that displays text
          files).

          http://www.greenwoodsoftware.com/less/

   screen
          terminal multiplexor

          https://www.gnu.org/software/screen/

   vim
          text editor

          https://www.vim.org/

Development activities

   Zeyd  Ben-Halim  started  ncurses  from  a  previous  package pcurses,
   written  by  Pavel  Curtis.  Eric  S.  Raymond  continued development.
   Juergen Pfeifer wrote most of the form and menu libraries.

   Ongoing development work is done by Thomas E. Dickey. Thomas E. Dickey
   has  acted  as  the maintainer for the Free Software Foundation, which
   holds  a  copyright on ncurses for releases 4.2 through 6.1. Following
   the release of ncurses 6.1, effective as of release 6.2, copyright for
   ncurses  reverted  to  Thomas  E.  Dickey  (see  the  ncurses  FAQ for
   additional information).

   Contact the current maintainers at

     bug-ncurses@gnu.org

   To join the ncurses mailing list, please write email to

     bug-ncurses-request@gnu.org

   containing the line:

     subscribe <name>@<host.domain>

   This list is open to anyone interested in helping with the development
   and testing of this package.

   Beta versions of ncurses are made available at

     ftp://ftp.invisible-island.net/ncurses/current/ and
     https://invisible-mirror.net/archives/ncurses/current/ .

   Patches to the current release are made available at

     ftp://ftp.invisible-island.net/ncurses/6.1/ and
     https://invisible-mirror.net/archives/ncurses/6.1/ .

   There is an archive of the mailing list here:

     http://lists.gnu.org/archive/html/bug-ncurses (also https)

Related resources

   The  release notes make scattered references to these pages, which may
   be interesting by themselves:
     * ncurses licensing
     * Symbol versioning in ncurses
     * Comments on ncurses versus slang (S-Lang)
     * tack - terminfo action checker
     * tctest - termcap library checker
     * Terminal Database

Other resources

   The  distribution  provides  a  newer  version  of the terminfo-format
   terminal description file once maintained by Eric Raymond . Unlike the
   older  version, the termcap and terminfo data are provided in the same
   file, which also provides several user-definable extensions beyond the
   X/Open specification.

   You  can  find  lots  of  information  on  terminal-related topics not
   covered  in  the  terminfo  file  at  Richard  Shuford's archive . The
   collection of computer manuals at bitsavers.org has also been useful.

     * Overview
     * Release Notes
          + Library improvements
               o New features
               o Other improvements
          + Program improvements
               o Utilities
               o Examples
          + Terminal database
          + Documentation
          + Interesting bug-fixes
          + Configuration changes
               o Major changes
               o Configuration options
          + Portability
     * Features of ncurses
     * Applications using ncurses
     * Development activities
     * Related resources
     * Other resources