Merged from emacs@sv.gnu.org

[emacs.git] / etc / TODO

                                                                -*-outline-*-

If you are ready to start working on any of these TODO items, we
appreciate your help; please write to emacs-devel@gnu.org so we can be
aware that the problem is being addressed, and talk with you how to do
it best.  Since Emacs is an FSF-copyrighted package, please be
prepared to sign legal papers to transfer the copyright on your work
to the FSF.

* Small but important fixes needed in existing features:

** Make vc-checkin avoid reverting the buffer if has not changed after
   the checkin. Comparing (md5 BUFFER) to (md5 FILE) should be enough.

** Make vc-annotate show place the cursor in the annotate buffer at the 
   same line as the current buffer.

** buffer-offer-save should be a permanent local.

** revert-buffer should eliminate overlays and the mark.

** erase-buffer should perhaps disregard read-only properties of text.

** Make occur correctly handle matches that span more than one line,
   as well as overlapping matches.

** Fix the kill/yank treatment of invisible text.  At the moment,
  invisible text is placed in the kill-ring, so that the contents of
  the ring may not correspond to the text as displayed to the user.
  It ought to be possible to omit text which is invisible (due to a
  text-property, overlay, or selective display) from the kill-ring.

** Change the way define-minor-mode handles autoloading.
  It should not generate :require.  Or :require in defcustom
  should not be recorded in the user's custom-set-variables call.

** The buttons at the top of a custom buffer should not omit
  variables whose values are currently hidden.

** Clean up the variables in browse-url.  Perhaps use a shell command string to
  specify the browser instead of the mushrooming set of functions.
  See also ESR's proposal for a BROWSER environment variable
  <URL:http://www.catb.org/~esr/BROWSER/browse-url.patch>.

** Enhance scroll-bar to handle tall line (similar to line-move).

** Make occur handle multi-line matches cleanly with context.

** In Custom buffers, put the option that turns a mode on or off first,
  using a heuristic of some kind?

** Define recompute-arg and recompute-arg-if for fix_command to use.
  See rms message of 11 Dec 05.

** Height returned by frame-parameter ... and height given to
   make-frame does not mean the same thing.  The former includes menu and
   tool bar lines, the latter don't.  frame-parameter should return height
   without menu and tool bar lines.

** In Emacs Info, examples of using Customize should be clickable
   and they should create Custom buffers.

** The toolbar should show keyboard equivalents in its tooltips.

** Modify allout.el to use overlays, like outline.el.

** M-! M-n should fetch the buffer-file-name as the default.

** Redesign the load-history data structure so it can cope better
  with evaluating definitions of the same function from different files,
  recording which file the latest definition came from.
  
* Important features:

** Provide user-friendly ways to list all available font families,
   list fonts, display a font as a sample, etc.  [fx is looking at
  multilingual font selection for the Unicode branch of Emacs.]

** Rewrite the face code to be simpler, clearer and faster.

** Program Enriched mode to read and save in RTF.  [Is there actually a
  decent single definition of RTF?  Maybe see info at
  http://latex2rtf.sourceforge.net/.]  This task seems to be addressed
  by http://savannah.nongnu.org/projects/emacs-rtf/, which is still in
  very early stages.

** Implement something better than the current Refill mode.  This
  probably needs some primitive support.

** Add a command to make a "Local Variables" section in the current buffer
  and/or add a variable to the list.

** Implement primitive and higher-level functions to allow filling
  properly with variable-pitch faces.

** Implement a smoother vertical scroll facility, one that allows
  C-v to scroll through a tall image.  The primitive operations
  posn-at-point and posn-at-x-y should now make it doable in elisp.

** Implement intelligent search/replace, going beyond query-replace
  (see http://graphics.csail.mit.edu/~rcm/chi04.pdf).

** Implement other text formatting properties.
*** Footnotes that can appear either in place or at the end of the page.
*** text property that says "don't break line in middle of this".
   Don't break the line between two characters that have the
   same value of this property.
*** Discretionary hyphens that are not visible when they are at end of line.

** Internationalize Emacs's messages.

** Install mmc@maruska.dyndns.org's no-flicker change.

** Add a "current vertical pixel level" value that goes with point,
  so that motion commands can also move through tall images.
  This value would be to point as window-vscroll is to window-start.

** Address internationalization of symbols names essentially
  as documentation, e.g. in command names and Custom.

** Make the Lucid menu widget display multilingual text.  [This
  probably needs to be done from actual Emacs buffers, either directly
  in the menu or by rendering in an unmapped window and copying the
  pixels.  The current code assumes a specific locale; that isn't good
  enough even if X can render the arbitrary text] [The gtk
  port now displays multilingual text in menus, but only insofar as
  Emacs can encode it as utf-8 and gtk can display the result.]
  Maybe making Lucid menus work like Gtk's (i.e. just force utf-8) is good
  enough now that Emacs can encode most chars into utf-8.

** Remove the limitation that window and frame widths and heights can
  be only full columns/lines.

* Other features we would like:

** Create a category of errors called `user-error' for errors which are
typically due to pilot errors and should thus be in debug-ignored-errors.

** Give Tar mode all the features of Archive mode.

** Create a category of errors called `process-error'
  for some or all errors associated with using subprocesses.

** Maybe reinterpret `parse-error' as a category of errors
  and put some other errors under it.

** A function to tell you the argument pattern of functions.
  See `function-arity' in http://www.loveshack.ukfsn.org/emacs/fx-misc.el.

** Make byte-compile warn when a doc string is too wide.

** A function to check for customizable options that have been
  set but not saved, and ask the user whether to save them.
  This could go in kill-emacs-query-functions, to remind people
  to save their changes. If the user says yes, show them
  in a Custom buffer using customize-customized.

** Emacs Lisp mode could put an overlay on the defun for every
  function that has advice.  The overlay could have `after-text' like "
  [Function has advice]".  It might look like
     (defun foo [Function has advice] (x y) 
  The overlay could also be a button that you could use to view the advice.

** ange-ftp
*** understand sftp
   This is hard to make work because sftp doesn't print status
   messages.

*** Use MLS for ange-ftp-insert-directory if a list of files is specified.

** Ability to map a key, including all modified-combinations.
   E.g map mouse-4 to wheel-up as well as M-mouse-4 -> M-wheel-up
   M-C-mouse-4 -> M-C-wheel-up, H-S-C-M-s-double-mouse-4 ->
   H-S-C-M-s-double-wheel-up, ...

** Beefed-up syntax-tables.
*** recognize multi-character syntactic entities like `begin' and `end'.
*** nested string-delimiters (for Postscript's (foo(bar)baz) strings).
*** support for infix operators (with precedence).
*** support for the $ (paired delimiter) in parse-partial-sexp.
*** support for hook-chars whose effect on the parsing-state is specified
        by elisp code.  Thus a char could both close a string and open a comment
        at the same time and do it in a context-sensitive way.
*** ability to add mode-specific data to the partial-parse-state.

** Add a way to convert a keyboard macro to equivalent Lisp code.

** Have a command suggestion help system that recognizes patterns
  of commands which could be replaced with a simpler common command.
  It should not make more than one suggestion per 10 minutes.

** Add a way to define input methods by computing them (when first used)
  from other input methods.  Then redefine C-x 8 to use a
  user-selected input method, with the default being the union of
  latin-1-prefix and latin-1-postfix.

** Implement a clean way to use different major modes for
  different parts of a buffer.  This could be useful in editing
  Bison input files, for instance, or other kinds of text
  where one language is embedded in another language.  See
  http://www.loveshack.ukfsn.org/emacs/multi-mode.el and also
  mmm-mode, as reference for approaches took by others.

** Arrange a way for an input method to return the first character
  immediately, then replace it later.  So that C-s a with
  input method latin-1-postfix would immediately search for an a.

** Give start-process the ability to direct standard-error
  output to a different filter.

** Make desktop.el save the "frame configuration" of Emacs (in some
  useful sense).

** Give desktop.el a feature to switch between different named
  desktops.

** Replace finder.el with something that generates an Info file
  which gives the same information through a menu structure.  [Dave
  Love started on this.]

** Add a cpio mode, more or less like tar mode.

** Implement a variant of uncompress.el or jka-compr.el that works with
  GNU Privacy Guard for encryption.  [Code exists but isn't assigned.
  See the Gnus development sources for assigned code concerning GPG
  use with mail, which is probably a good start.]  See also
  http://www.loveshack.ukfsn.org/emacs/auto-crypt.tgz.

** Save undo information in special temporary files, and reload it
  when needed for undoing.  This could extend undo capacity.

** Change the Windows NT menu code
  so that it handles the deep_p argument and avoids
  regenerating the whole menu bar menu tree except
  when the user tries to use the menubar.

  This requires the RIT to forward the WM_INITMENU message to
  the main thread, and not return from that message until the main
  thread has processed the MENU_BAR_ACTIVATE_EVENT and regenerated
  the whole menu bar.  In the mean time, it should process other messages.

** Get some major packages installed: W3 (development version needs
  significant work), PSGML.  Check the assignments file for other
  packages which might go in and have been missed.

** Make keymaps a first-class Lisp object (this means a rewrite of
  keymap.c).  What should it do apart from being opaque ?
  multiple inheritance ?  faster where-is ?  no more fix_submap_inheritance ?
  what else ?

** Provide real menus on ttys.  The MS-DOS implementation can serve as
  an example how to do part of this.

** Implement popular parts of the rest of the CL functions as compiler
  macros in cl-macs.

** Make compiler warnings about functions that might be undefined at run time
 smarter, so that they know which files are required by the file being
 compiled and don't warn about functions defined in them.

** Highlight rectangles (`mouse-track-rectangle-p' in XEmacs).  Already in CUA,
  but it's a valuable feature worth making more general.

** Support simultaneous tty and X frames.  [See the multi-tty branch of Emacs 
  at http://lorentey.hu/project/emacs.]

** Provide MIME support for Rmail using the Gnus MIME library.  [Maybe
  not now feasible, given Gnus maintenance decisions.  fx looked at
  this and can say where some of the problems are.]

** Eliminate the storm of warnings concerning char/unsigned char
  mismatches that we get with GCC 4.x and proprietary compilers on
  various systems.  They make it difficult to spot the important
  warnings.

** Fix anything necessary to use `long long' EMACS_INTs with GCC.

** Split out parts of lisp.h and generate Makefile dependencies
  automatically.

** Update the FAQ.

** Allow auto-compression-mode to use zlib calls if zlib is available.
  [It's required for PNG, so may be linked anyhow.]

** Add a --pristine startup flag which does -q --no-site-file plus
  ignoring X resources (Doze equivalents?) and most of the
  environment.  What should not be ignored needs consideration.

** Improve the GC (generational, incremental).  (We may be able to use
  the Boehm collector.)  [See the Boehm-GC branch in CVS for work on
  this.]

** Check what hooks would help Emacspeak -- see the defadvising in W3.

** Add horizontal scroll bars.

** Provide an optional feature which computes a scroll bar slider's
  size and its position from lines instead of characters.

** Add support for SVG (Scalable Vector Graphics) rendering to
  Emacs.

** Allow unknown image types to be rendered via an external program
  converting them to, say, PBM (in the same way as PostScript?).

** Allow displaying an X window from an external program in a buffer,
  e.g. to render graphics from Java applets.  [gerd and/or wmperry
  thought this was feasible.]

** Allow images (not just text) in the margin to be mouse-sensitive.
  (Requires recursing through display properties).  Provide some way
  to simulate mouse-clicks on marginal text without a mouse.

** Implement Lisp functions to determine properly whether a character
  is displayable (particularly needed in XFree 4, sigh).  Use it to
  define useful glyphs that may be displayed as images or unicodes
  (with ASCIIfied fallback via latin1-disp).  Examples include
  box-drawing graphics in Custom buffers, W3 rules and tables, and
  tree displays generally, mode-line mail indicator.  [See work done
  already for Emacs 22 and consult fx.]

** Do something to make rms happy with fx's dynamic loading, and use it
  to implement things like auto-loaded buffer parsers and database
  access in cases which need more than Lisp.

** Extend ps-print to deal with multiple font sizes, images, and extra
  encodings.

** Provide portable undumping using mmap (per gerd design).

** Make byte-compile avoid binding an expanded defsubst's args
when the body only calls primitives.

** Use the XIE X extension, if available, for image display.

** Make monochrome images display using the foreground and background
  colors of the applicable faces.

** Face remapping.

** Optionally make the cursor a little thinner at the end of a line
  or the end of the buffer.

** Add support for rendering antialiased text, probably using
  XRender/Freetype.

** Port the conservative stack marking code of Emacs' garbage collector
  to more systems, so that we can completely get rid of GCPROs.  Note
  that Boehm garbage collector provides this.

** Reorder defcustom's in each package so that the more important
  options come first in the Customize buffers.  This could be done by
  either rearranging the file (since options are shown in the order
  they appear in the *.el files), or by adding a few :set-after
  attributes.

** Maybe document the features of libraries missing from the manual (or
  ancillary manuals, including the Lisp manual in some cases).
  This is not worth doing for all of these packages and we need not
  aim for completeness, but some may be worth documenting.

  Here's a list which is probably not complete/correct: align, allout,
  artist, ansi-color, array, battery, calculator, cdl, cmuscheme,
  completion, cua, delim-col, dirtrack, double, echistory, elide-head,
  easymenu, expand, flow-ctrl, format [format-alist],
  generic/generic-x [various modes], kermit, log-edit, ledit
  [obsolete?], makesum, midnight [other than in Kill Buffer node],
  mouse-copy [?], mouse-drag, mouse-sel, net-utils, rcompile,
  snmp-mode [?], soundex [should be interactive?], strokes [start from
  the web page], talk, thingatpt [interactive functions?], type-break,
  vcursor, xscheme, zone-mode [?], mlconvert [?], iso-cvt, iso-swed,
  swedish, feedmail [?], uce, bruce, gametree, meese, page-ext,
  refbib, refer, scribe, sgml-mode, spell, texinfo, underline,
  cmacexp, hideif, mantemp [obsolete?], pcomplete, assoc, xml,
  cvs-status (should be described in PCL-CVS manual); other progmodes,
  probably in separate manual.

** Convert the XPM bitmaps to PPM, replace the PBMs with them and scrap
  the XPMs so that the colour versions work generally.  (Requires care
  with the colour used for the transparent regions.)

** Convenient access to the `values' variable.  It would be nice to have an
  interface that would show you the printed reps of the elements of the
  list in a menu, let you select one of the values, and put it into some
  other variable, without changing the value of `values'.

** (Controlled by a flag) make open and close syntax match exactly,
  i.e. `(' doesn't match `]'.

** Specify parameter ID-FORMAT in all calls to `file-attributes' and
  `directory-files-and-attributes' where attributes UID or GID are used.
  Whenever possible, use value 'string.
  When done, change meaning of default value from 'integer to 'string.
  If value 'integer is used nowhere, remove the parameter ID-FORMAT from
  the definition of `file-attributes' and `directory-files-and-attributes'
  and from the calls.

** Make language-info-alist customizable.  Currently a user can customize
  only the variable `current-language-environment'.

** Improve language environment handling so that Emacs can fit
  better to a users locale.  Currently Emacs uses utf-8 language
  environment for all utf-8 locales, thus a user in ja_JP.UTF-8 locale
  are also put in utf-8 lang. env.  In such a case, it is
  better to use Japanese lang. env. but prefer utf-8 coding system.

** Enhance locale handling:  handle language, territory and charset
  orthogonally and de-emphasize language environments.  Use the locale
  to set up more things, such as fontsets, the default Ispell
  dictionary, diary format, calendar holidays and display, quoting
  characters and phrase boundaries, sentence endings, collation for
  sorting (at least for unicodes), HTTP Accept-language, patterns for
  directory listings and compilation messages, yes-or-no replies,
  common menu items when the toolkit supports it ...  `locale-info'
  needs extending for LC_COLLATE &c.  [fx started on this.]

** Eliminate the current restriction on header printing by ps-print.
  Currently, a header can contain only single 1-byte charset in
  addition to ASCII.

** In ps-print, provide an user friendly interface to specify fonts.

** OpenType font support for various complex scripts (e.g. Devanagari).
  As X protocal doesn't provide a way to access OpenType Layout Tables
  in a OpenType font of a server side, we need a way to utilize local
  fonts (perhaps by directly using the Freetype library or indirectly
  via Xft library).

** Enhance word boundary detection for such a script that doesn't use
  space at word boundary (e.g. Thai).

** Implement interface programs with major Japanese conversion server
  in lib-src so that they can be used from the input method
  "japanese".  Currently, most Japanese users are using external
  packages (e.g. tamago, anthy) or an input method via XIM.

** Let LEIM handle the Mode_switch key like XIM does (i.e. a toggle like C-\
but which can also be used as a modifier).

** Provide the toolbar on ttys. This could map a bit like tmm-menubar
   for the menubar and buttons could look a bit like those used by customize.

** Improve Help buffers: Change the face of previously visited links (like
   Info, but also with regard to namespace), add a forward button to make the
   Help buffer more browser like and gives the value of lisp expressions
   e.g auto-mode-alist, the right face. [nickrob@snap.net.nz has a patch
   for this for inclusion after 22.1].

** Possibly make `list-holidays' eval items in the calendar-holidays variable.
   See thread
   <http://lists.gnu.org/archive/html/emacs-devel/2006-02/msg01034.html>.
   [rgm@gnu.org will look at this after 22.1]

* Internal changes

** Replace gmalloc.c with the modified Doug Lea code from the current
  GNU libc so that the special mmapping of buffers can be removed --
  that apparently loses under Solaris, at least. [fx has mostly done
  this.]

** Rewrite make-docfile to be clean and maintainable.

** Add an inferior-comint-minor-mode to capture the common set of operations
   offered by major modes that offer an associated inferior
   comint-derived mode.  I.e. basically make cmuscheme.el/inf-lisp.el generic.
   For use by sml-mode, python-mode, tex-mode, scheme-mode, lisp-mode,
   haskell-mode, tuareg-mode, ...

** Make SYNC_INPUT the default.
   All loops using immediate_quit need to be checked to ensure that
   C-g can interrupt them, in case of an infinite loop.  Once we
   switch to using SYNC_INPUT, we can remove the BLOCK_INPUTs in the
   allocation functions (allocate_string etc.) without worrying about
   data munging.

* Other known bugs:

** a two-char comment-starter whose two chars are symbol constituents will
not be noticed if it appears within a word.

** Fix unexelf.c to handle the .data.rel and .data.rel.local
   sections made by GCC 3.4 on IRIX.

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