(cvs-mode-revert-buffer): Doc fix.

[emacs.git] / lisp / cus-edit.el

;;; cus-edit.el --- Tools for customizing Emacs and Lisp packages.
;;
;; Copyright (C) 1996, 1997, 1999, 2000 Free Software Foundation, Inc.
;;
;; Author: Per Abrahamsen <abraham@dina.kvl.dk>
;; Keywords: help, faces

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:
;;
;; This file implements the code to create and edit customize buffers.
;; 
;; See `custom.el'.

;; No commands should have names starting with `custom-' because
;; that interferes with completion.  Use `customize-' for commands
;; that the user will run with M-x, and `Custom-' for interactive commands.

;;; Code:

(require 'cus-face)
(require 'wid-edit)
(eval-when-compile
  (defvar custom-versions-load-alist))  ; from cus-load

(condition-case nil
    (require 'cus-load)
  (error nil))

(condition-case nil
    (require 'cus-start)
  (error nil))

(put 'custom-define-hook 'custom-type 'hook)
(put 'custom-define-hook 'standard-value '(nil))
(custom-add-to-group 'customize 'custom-define-hook 'custom-variable)

;;; Customization Groups.

(defgroup emacs nil
  "Customization of the One True Editor."
  :link '(custom-manual "(emacs)Top"))

;; Most of these groups are stolen from `finder.el',
(defgroup editing nil
  "Basic text editing facilities."
  :group 'emacs)

(defgroup abbrev nil
  "Abbreviation handling, typing shortcuts, macros."
  :tag "Abbreviations"
  :group 'editing)

(defgroup matching nil
  "Various sorts of searching and matching."
  :group 'editing)

(defgroup emulations nil
  "Emulations of other editors."
  :group 'editing)

(defgroup mouse nil
  "Mouse support."
  :group 'editing)

(defgroup outlines nil
  "Support for hierarchical outlining."
  :group 'editing)

(defgroup external nil
  "Interfacing to external utilities."
  :group 'emacs)

(defgroup bib nil
  "Code related to the `bib' bibliography processor."
  :tag "Bibliography"
  :group 'external)

(defgroup processes nil
  "Process, subshell, compilation, and job control support."
  :group 'external
  :group 'development)

(defgroup convenience nil
  "Convenience features for faster editing."
  :group 'emacs)

(defgroup programming nil
  "Support for programming in other languages."
  :group 'emacs)

(defgroup languages nil
  "Specialized modes for editing programming languages."
  :group 'programming)

(defgroup lisp nil
  "Lisp support, including Emacs Lisp."
  :group 'languages
  :group 'development)

(defgroup c nil
  "Support for the C language and related languages."
  :group 'languages)

(defgroup tools nil
  "Programming tools."
  :group 'programming)

(defgroup oop nil
  "Support for object-oriented programming."
  :group 'programming)

(defgroup applications nil
  "Applications written in Emacs."
  :group 'emacs)

(defgroup calendar nil
  "Calendar and time management support."
  :group 'applications)

(defgroup mail nil
  "Modes for electronic-mail handling."
  :group 'applications)

(defgroup news nil
  "Support for netnews reading and posting."
  :group 'applications)

(defgroup games nil
  "Games, jokes and amusements."
  :group 'applications)

(defgroup development nil
  "Support for further development of Emacs."
  :group 'emacs)

(defgroup docs nil
  "Support for Emacs documentation."
  :group 'development)

(defgroup extensions nil
  "Emacs Lisp language extensions."
  :group 'development)

(defgroup internal nil
  "Code for Emacs internals, build process, defaults."
  :group 'development)

(defgroup maint nil
  "Maintenance aids for the Emacs development group."
  :tag "Maintenance"
  :group 'development)

(defgroup environment nil
  "Fitting Emacs with its environment."
  :group 'emacs)

(defgroup comm nil
  "Communications, networking, remote access to files."
  :tag "Communication"
  :group 'environment)

(defgroup hardware nil
  "Support for interfacing with exotic hardware."
  :group 'environment)

(defgroup terminals nil
  "Support for terminal types."
  :group 'environment)

(defgroup unix nil
  "Front-ends/assistants for, or emulators of, UNIX features."
  :group 'environment)

(defgroup vms nil
  "Support code for vms."
  :group 'environment)

(defgroup i18n nil
  "Internationalization and alternate character-set support."
  :group 'environment
  :group 'editing)

(defgroup x nil
  "The X Window system."
  :group 'environment)

(defgroup frames nil
  "Support for Emacs frames and window systems."
  :group 'environment)

(defgroup data nil
  "Support editing files of data."
  :group 'emacs)

(defgroup files nil
  "Support editing files."
  :group 'emacs)

(defgroup wp nil
  "Word processing."
  :group 'emacs)

(defgroup tex nil
  "Code related to the TeX formatter."
  :group 'wp)

(defgroup faces nil
  "Support for multiple fonts."
  :group 'emacs)

(defgroup hypermedia nil
  "Support for links between text or other media types."
  :group 'emacs)

(defgroup help nil
  "Support for on-line help systems."
  :group 'emacs)

(defgroup multimedia nil
  "Non-textual support, specifically images and sound."
  :group 'emacs)

(defgroup local nil
  "Code local to your site."
  :group 'emacs)

(defgroup customize '((widgets custom-group))
  "Customization of the Customization support."
  :link '(custom-manual "(elisp)Customization")
  :link '(url-link :tag "(Old?) Development Page"
                   "http://www.dina.kvl.dk/~abraham/custom/")
  :prefix "custom-"
  :group 'help)

(defgroup custom-faces nil
  "Faces used by customize."
  :group 'customize
  :group 'faces)

(defgroup custom-browse nil
  "Control customize browser."
  :prefix "custom-"
  :group 'customize)

(defgroup custom-buffer nil
  "Control customize buffers."
  :prefix "custom-"
  :group 'customize)

(defgroup custom-menu nil
  "Control customize menus."
  :prefix "custom-"
  :group 'customize)

(defgroup abbrev-mode nil
  "Word abbreviations mode."
  :group 'abbrev)

(defgroup alloc nil
  "Storage allocation and gc for GNU Emacs Lisp interpreter."
  :tag "Storage Allocation"
  :group 'internal)

(defgroup undo nil
  "Undoing changes in buffers."
  :group 'editing)

(defgroup modeline nil
  "Content of the modeline."
  :group 'environment)

(defgroup fill nil
  "Indenting and filling text."
  :group 'editing)

(defgroup editing-basics nil
  "Most basic editing facilities."
  :group 'editing)

(defgroup display nil
  "How characters are displayed in buffers."
  :group 'environment)

(defgroup execute nil
  "Executing external commands."
  :group 'processes)

(defgroup installation nil
  "The Emacs installation."
  :group 'environment)

(defgroup dired nil
  "Directory editing."
  :group 'environment)

(defgroup limits nil
  "Internal Emacs limits."
  :group 'internal)

(defgroup debug nil
  "Debugging Emacs itself."
  :group 'development)

(defgroup minibuffer nil
  "Controling the behaviour of the minibuffer."
  :group 'environment)

(defgroup keyboard nil
  "Input from the keyboard."
  :group 'environment)

(defgroup mouse nil
  "Input from the mouse."
  :group 'environment)

(defgroup menu nil
  "Input from the menus."
  :group 'environment)

(defgroup auto-save nil
  "Preventing accidential loss of data."
  :group 'files)

(defgroup processes-basics nil
  "Basic stuff dealing with processes."
  :group 'processes)

(defgroup mule nil
  "MULE Emacs internationalization."
  :group 'i18n)

(defgroup windows nil
  "Windows within a frame."
  :group 'environment)

;;; Utilities.

(defun custom-quote (sexp)
  "Quote SEXP iff it is not self quoting."
  (if (or (memq sexp '(t nil))
          (keywordp sexp)
          (and (listp sexp)
               (memq (car sexp) '(lambda)))
          (stringp sexp)
          (numberp sexp)
          (vectorp sexp)
;;;       (and (fboundp 'characterp)
;;;            (characterp sexp))
          )
      sexp
    (list 'quote sexp)))

(defun custom-split-regexp-maybe (regexp)
  "If REGEXP is a string, split it to a list at `\\|'.
You can get the original back with from the result with:
  (mapconcat 'identity result \"\\|\")

IF REGEXP is not a string, return it unchanged."
  (if (stringp regexp)
      (let ((start 0)
            all)
        (while (string-match "\\\\|" regexp start)
          (setq all (cons (substring regexp start (match-beginning 0)) all)
                start (match-end 0)))
        (nreverse (cons (substring regexp start) all)))
    regexp))

(defun custom-variable-prompt ()
  "Prompt for a variable, defaulting to the variable at point.
Return a list suitable for use in `interactive'."
   (let ((v (variable-at-point))
         (enable-recursive-minibuffers t)
         val)
     (setq val (completing-read
                (if (symbolp v)
                    (format "Customize option: (default %s) " v)
                  "Customize variable: ")
                obarray (lambda (symbol)
                          (and (boundp symbol)
                               (or (get symbol 'custom-type)
                                   (get symbol 'custom-loads)
                                   (get symbol 'standard-value)))) t))
     (list (if (equal val "")
               (if (symbolp v) v nil)
             (intern val)))))

(defun custom-menu-filter (menu widget)
  "Convert MENU to the form used by `widget-choose'.
MENU should be in the same format as `custom-variable-menu'.
WIDGET is the widget to apply the filter entries of MENU on."
  (let ((result nil)
        current name action filter)
    (while menu
      (setq current (car menu)
            name (nth 0 current)
            action (nth 1 current)
            filter (nth 2 current)
            menu (cdr menu))
      (if (or (null filter) (funcall filter widget))
          (push (cons name action) result)
        (push name result)))
    (nreverse result)))

;;; Unlispify.

(defvar custom-prefix-list nil
  "List of prefixes that should be ignored by `custom-unlispify'.")

(defcustom custom-unlispify-menu-entries t
  "Display menu entries as words instead of symbols if non nil."
  :group 'custom-menu
  :type 'boolean)

(defcustom custom-unlispify-remove-prefixes nil
  "Non-nil means remove group prefixes from option names in buffer."
  :group 'custom-menu
  :type 'boolean)

(defun custom-unlispify-menu-entry (symbol &optional no-suffix)
  "Convert SYMBOL into a menu entry."
  (cond ((not custom-unlispify-menu-entries)
         (symbol-name symbol))
        ((get symbol 'custom-tag)
         (if no-suffix
             (get symbol 'custom-tag)
           (concat (get symbol 'custom-tag) "...")))
        (t
         (save-excursion
           (set-buffer (get-buffer-create " *Custom-Work*"))
           (erase-buffer)
           (princ symbol (current-buffer))
           (goto-char (point-min))
           (when (and (eq (get symbol 'custom-type) 'boolean)
                      (re-search-forward "-p\\'" nil t))
             (replace-match "" t t)
             (goto-char (point-min)))
           (if custom-unlispify-remove-prefixes
               (let ((prefixes custom-prefix-list)
                     prefix)
                 (while prefixes
                   (setq prefix (car prefixes))
                   (if (search-forward prefix (+ (point) (length prefix)) t)
                       (progn
                         (setq prefixes nil)
                         (delete-region (point-min) (point)))
                     (setq prefixes (cdr prefixes))))))
           (subst-char-in-region (point-min) (point-max) ?- ?\  t)
           (capitalize-region (point-min) (point-max))
           (unless no-suffix
             (goto-char (point-max))
             (insert "..."))
           (buffer-string)))))

(defcustom custom-unlispify-tag-names t
  "Display tag names as words instead of symbols if non nil."
  :group 'custom-buffer
  :type 'boolean)

(defun custom-unlispify-tag-name (symbol)
  "Convert SYMBOL into a menu entry."
  (let ((custom-unlispify-menu-entries custom-unlispify-tag-names))
    (custom-unlispify-menu-entry symbol t)))

(defun custom-prefix-add (symbol prefixes)
  "Add SYMBOL to list of ignored PREFIXES."
  (cons (or (get symbol 'custom-prefix)
            (concat (symbol-name symbol) "-"))
        prefixes))

;;; Guess.

(defcustom custom-guess-name-alist
  '(("-p\\'" boolean)
    ("-hook\\'" hook)
    ("-face\\'" face)
    ("-file\\'" file)
    ("-function\\'" function)
    ("-functions\\'" (repeat function))
    ("-list\\'" (repeat sexp))
    ("-alist\\'" (repeat (cons sexp sexp))))
  "Alist of (MATCH TYPE).

MATCH should be a regexp matching the name of a symbol, and TYPE should
be a widget suitable for editing the value of that symbol.  The TYPE
of the first entry where MATCH matches the name of the symbol will be
used.

This is used for guessing the type of variables not declared with
customize."
  :type '(repeat (group (regexp :tag "Match") (sexp :tag "Type")))
  :group 'customize)

(defcustom custom-guess-doc-alist
  '(("\\`\\*?Non-nil " boolean))
  "Alist of (MATCH TYPE).

MATCH should be a regexp matching a documentation string, and TYPE
should be a widget suitable for editing the value of a variable with
that documentation string.  The TYPE of the first entry where MATCH
matches the name of the symbol will be used.

This is used for guessing the type of variables not declared with
customize."
  :type '(repeat (group (regexp :tag "Match") (sexp :tag "Type")))
  :group 'customize)

(defun custom-guess-type (symbol)
  "Guess a widget suitable for editing the value of SYMBOL.
This is done by matching SYMBOL with `custom-guess-name-alist' and
if that fails, the doc string with `custom-guess-doc-alist'."
  (let ((name (symbol-name symbol))
        (names custom-guess-name-alist)
        current found)
    (while names
      (setq current (car names)
            names (cdr names))
      (when (string-match (nth 0 current) name)
        (setq found (nth 1 current)
              names nil)))
    (unless found
      (let ((doc (documentation-property symbol 'variable-documentation))
            (docs custom-guess-doc-alist))
        (when doc
          (while docs
            (setq current (car docs)
                  docs (cdr docs))
            (when (string-match (nth 0 current) doc)
              (setq found (nth 1 current)
                    docs nil))))))
    found))

;;; Sorting.

(defcustom custom-browse-sort-alphabetically nil
  "If non-nil, sort members of each customization group alphabetically."
  :type 'boolean
  :group 'custom-browse)

(defcustom custom-browse-order-groups nil
  "If non-nil, order group members within each customization group.
If `first', order groups before non-groups.
If `last', order groups after non-groups."
  :type '(choice (const first)
                 (const last)
                 (const :tag "none" nil))
  :group 'custom-browse)

(defcustom custom-browse-only-groups nil
  "If non-nil, show group members only within each customization group."
  :type 'boolean
  :group 'custom-browse)

(defcustom custom-buffer-sort-alphabetically nil
  "If non-nil, sort members of each customization group alphabetically."
  :type 'boolean
  :group 'custom-buffer)

(defcustom custom-buffer-order-groups 'last
  "If non-nil, order group members within each customization group.
If `first', order groups before non-groups.
If `last', order groups after non-groups."
  :type '(choice (const first)
                 (const last)
                 (const :tag "none" nil))
  :group 'custom-buffer)

(defcustom custom-menu-sort-alphabetically nil
  "If non-nil, sort members of each customization group alphabetically."
  :type 'boolean
  :group 'custom-menu)

(defcustom custom-menu-order-groups 'first
  "If non-nil, order group members within each customization group.
If `first', order groups before non-groups.
If `last', order groups after non-groups."
  :type '(choice (const first)
                 (const last)
                 (const :tag "none" nil))
  :group 'custom-menu)

;;;###autoload (add-hook 'same-window-regexps "\\`\\*Customiz.*\\*\\'")

(defun custom-sort-items (items sort-alphabetically order-groups)
  "Return a sorted copy of ITEMS.
ITEMS should be a `custom-group' property.
If SORT-ALPHABETICALLY non-nil, sort alphabetically.
If ORDER-GROUPS is `first' order groups before non-groups, if `last' order
groups after non-groups, if nil do not order groups at all."
  (sort (copy-sequence items)
   (lambda (a b)
     (let ((typea (nth 1 a)) (typeb (nth 1 b))
           (namea (nth 0 a)) (nameb (nth 0 b)))
       (cond ((not order-groups)
              ;; Since we don't care about A and B order, maybe sort.
              (when sort-alphabetically
                (string-lessp namea nameb)))
             ((eq typea 'custom-group)
              ;; If B is also a group, maybe sort.  Otherwise, order A and B.
              (if (eq typeb 'custom-group)
                  (when sort-alphabetically
                    (string-lessp namea nameb))
                (eq order-groups 'first)))
             ((eq typeb 'custom-group)
              ;; Since A cannot be a group, order A and B.
              (eq order-groups 'last))
             (sort-alphabetically
              ;; Since A and B cannot be groups, sort.
              (string-lessp namea nameb)))))))

;;; Custom Mode Commands.

(defvar custom-options nil
  "Customization widgets in the current buffer.")

(defun Custom-set ()
  "Set changes in all modified options."
  (interactive)
  (let ((children custom-options))
    (mapc (lambda (child)
            (when (eq (widget-get child :custom-state) 'modified)
              (widget-apply child :custom-set)))
            children)))

(defun Custom-save ()
  "Set all modified group members and save them."
  (interactive)
  (let ((children custom-options))
    (mapc (lambda (child)
            (when (memq (widget-get child :custom-state)
                        '(modified set changed rogue))
              (widget-apply child :custom-save)))
            children))
  (custom-save-all))

(defvar custom-reset-menu
  '(("Current" . Custom-reset-current)
    ("Saved" . Custom-reset-saved)
    ("Erase Customization (use standard settings)" . Custom-reset-standard))
  "Alist of actions for the `Reset' button.
The key is a string containing the name of the action, the value is a
Lisp function taking the widget as an element which will be called
when the action is chosen.")

(defun custom-reset (event)
  "Select item from reset menu."
  (let* ((completion-ignore-case t)
         (answer (widget-choose "Reset to"
                                custom-reset-menu
                                event)))
    (if answer
        (funcall answer))))

(defun Custom-reset-current (&rest ignore)
  "Reset all modified group members to their current value."
  (interactive)
  (let ((children custom-options))
    (mapc (lambda (widget)
            (and (default-boundp (widget-value widget))
                 (if (memq (widget-get widget :custom-state)
                           '(modified changed))
                     (widget-apply widget :custom-reset-current))))
            children)))

(defun Custom-reset-saved (&rest ignore)
  "Reset all modified or set group members to their saved value."
  (interactive)
  (let ((children custom-options))
    (mapc (lambda (widget)
            (and (get (widget-value widget) 'saved-value)
                 (if (memq (widget-get widget :custom-state)
                           '(modified set changed rogue))
                     (widget-apply widget :custom-reset-saved))))
            children)))

(defun Custom-reset-standard (&rest ignore)
  "Erase all customization (either current or saved) for the group members.
The immediate result is to restore them to their standard settings.
This operation eliminates any saved settings for the group members,
making them as if they had never been customized at all."
  (interactive)
  (let ((children custom-options))
    (mapc (lambda (widget)
            (and (get (widget-value widget) 'standard-value)
                 (if (memq (widget-get widget :custom-state)
                           '(modified set changed saved rogue))
                     (widget-apply widget :custom-reset-standard))))
            children)))

;;; The Customize Commands

(defun custom-prompt-variable (prompt-var prompt-val &optional comment)
  "Prompt for a variable and a value and return them as a list.
PROMPT-VAR is the prompt for the variable, and PROMPT-VAL is the
prompt for the value.  The %s escape in PROMPT-VAL is replaced with
the name of the variable.

If the variable has a `variable-interactive' property, that is used as if
it were the arg to `interactive' (which see) to interactively read the value.

If the variable has a `custom-type' property, it must be a widget and the
`:prompt-value' property of that widget will be used for reading the value.

If optional COMMENT argument is non nil, also prompt for a comment and return
it as the third element in the list."
  (let* ((var (read-variable prompt-var))
         (minibuffer-help-form '(describe-variable var))
         (val
          (let ((prop (get var 'variable-interactive))
                (type (get var 'custom-type))
                (prompt (format prompt-val var)))
            (unless (listp type)
              (setq type (list type)))
            (cond (prop
                   ;; Use VAR's `variable-interactive' property
                   ;; as an interactive spec for prompting.
                   (call-interactively (list 'lambda '(arg)
                                             (list 'interactive prop)
                                             'arg)))
                  (type
                   (widget-prompt-value type
                                        prompt
                                        (if (boundp var)
                                            (symbol-value var))
                                        (not (boundp var))))
                  (t
                   (eval-minibuffer prompt))))))
    (if comment
        (list var val
              (read-string "Comment: " (get var 'variable-comment)))
      (list var val))))

;;;###autoload
(defun customize-set-value (var val &optional comment)
  "Set VARIABLE to VALUE.  VALUE is a Lisp object.

If VARIABLE has a `variable-interactive' property, that is used as if
it were the arg to `interactive' (which see) to interactively read the value.

If VARIABLE has a `custom-type' property, it must be a widget and the
`:prompt-value' property of that widget will be used for reading the value.

If given a prefix (or a COMMENT argument), also prompt for a comment."
  (interactive (custom-prompt-variable "Set variable: "
                                       "Set %s to value: "
                                       current-prefix-arg))
   
  (set var val)
  (cond ((string= comment "")
         (put var 'variable-comment nil))
        (comment
         (put var 'variable-comment comment))))

;;;###autoload
(defun customize-set-variable (variable value &optional comment)
  "Set the default for VARIABLE to VALUE.  VALUE is a Lisp object.

If VARIABLE has a `custom-set' property, that is used for setting
VARIABLE, otherwise `set-default' is used.

The `customized-value' property of the VARIABLE will be set to a list
with a quoted VALUE as its sole list member.

If VARIABLE has a `variable-interactive' property, that is used as if
it were the arg to `interactive' (which see) to interactively read the value.

If VARIABLE has a `custom-type' property, it must be a widget and the
`:prompt-value' property of that widget will be used for reading the value.

If given a prefix (or a COMMENT argument), also prompt for a comment."
  (interactive (custom-prompt-variable "Set variable: "
                                       "Set customized value for %s to: "
                                       current-prefix-arg))
  (funcall (or (get variable 'custom-set) 'set-default) variable value)
  (put variable 'customized-value (list (custom-quote value)))
  (cond ((string= comment "")
         (put variable 'variable-comment nil)
         (put variable 'customized-variable-comment nil))
        (comment
         (put variable 'variable-comment comment)
         (put variable 'customized-variable-comment comment))))

;;;###autoload
(defun customize-save-variable (var value &optional comment)
  "Set the default for VARIABLE to VALUE, and save it for future sessions.
If VARIABLE has a `custom-set' property, that is used for setting
VARIABLE, otherwise `set-default' is used.

The `customized-value' property of the VARIABLE will be set to a list
with a quoted VALUE as its sole list member.

If VARIABLE has a `variable-interactive' property, that is used as if
it were the arg to `interactive' (which see) to interactively read the value.

If VARIABLE has a `custom-type' property, it must be a widget and the
`:prompt-value' property of that widget will be used for reading the value.

If given a prefix (or a COMMENT argument), also prompt for a comment."
  (interactive (custom-prompt-variable "Set and ave variable: "
                                       "Set and save value for %s as: "
                                       current-prefix-arg))
  (funcall (or (get var 'custom-set) 'set-default) var value)
  (put var 'saved-value (list (custom-quote value)))
  (cond ((string= comment "")
         (put var 'variable-comment nil)
         (put var 'saved-variable-comment nil))
        (comment
         (put var 'variable-comment comment)
         (put var 'saved-variable-comment comment)))
  (custom-save-all))

;;;###autoload
(defun customize ()
  "Select a customization buffer which you can use to set user options.
User options are structured into \"groups\".
Initially the top-level group `Emacs' and its immediate subgroups
are shown; the contents of those subgroups are initially hidden."
  (interactive)
  (customize-group 'emacs))

;;;###autoload
(defun customize-group (group)
  "Customize GROUP, which must be a customization group."
  (interactive (list (let ((completion-ignore-case t))
                       (completing-read "Customize group: (default emacs) "
                                        obarray
                                        (lambda (symbol)
                                          (or (get symbol 'custom-loads)
                                              (get symbol 'custom-group)))
                                        t))))
  (when (stringp group)
    (if (string-equal "" group)
        (setq group 'emacs)
      (setq group (intern group))))
  (or (get group 'custom-group)
      (custom-load-symbol group))
  (let ((name (format "*Customize Group: %s*"
                      (custom-unlispify-tag-name group))))
    (if (get-buffer name)
        (pop-to-buffer name)
      (custom-buffer-create (list (list group 'custom-group))
                            name
                            (concat " for group "
                                    (custom-unlispify-tag-name group))))))

;;;###autoload
(defun customize-group-other-window (group)
  "Customize GROUP, which must be a customization group."
  (interactive (list (let ((completion-ignore-case t))
                       (completing-read "Customize group: (default emacs) "
                                        obarray
                                        (lambda (symbol)
                                          (or (get symbol 'custom-loads)
                                              (get symbol 'custom-group)))
                                        t))))
  (when (stringp group)
    (if (string-equal "" group)
        (setq group 'emacs)
      (setq group (intern group))))
  (or (get group 'custom-group)
      (custom-load-symbol group))
  (let ((name (format "*Customize Group: %s*"
                      (custom-unlispify-tag-name group))))
    (if (get-buffer name)
        (let ((window (selected-window)))
          (pop-to-buffer name)
          (select-window window))
      (custom-buffer-create-other-window
       (list (list group 'custom-group))
       name
       (concat " for group "
               (custom-unlispify-tag-name group))))))

;;;###autoload
(defalias 'customize-variable 'customize-option)

;;;###autoload
(defun customize-option (symbol)
  "Customize SYMBOL, which must be a user option variable."
  (interactive (custom-variable-prompt))
  ;; If we don't have SYMBOL's real definition loaded,
  ;; try to load it.
  (unless (get symbol 'custom-type)
    (let ((loaddefs-file (locate-library "loaddefs.el" t))
          file)
      ;; See if it is autoloaded from some library.
      (when loaddefs-file
        (with-temp-buffer
          (insert-file-contents loaddefs-file)
          (when (re-search-forward (concat "^(defvar " (symbol-name symbol))
                                   nil t)
            (search-backward "\n;;; Generated autoloads from ")
            (goto-char (match-end 0))
            (setq file (buffer-substring (point)
                                         (progn (end-of-line) (point)))))))
      ;; If it is, load that library.
      (when file
        (when (string-match "\\.el\\'" file)
          (setq file (substring file 0 (match-beginning 0))))
        (load file))))
  (unless (get symbol 'custom-type)
    (error "Variable %s cannot be customized" symbol))
  (custom-buffer-create (list (list symbol 'custom-variable))
                        (format "*Customize Option: %s*"
                                (custom-unlispify-tag-name symbol))))

(defvar customize-changed-options-previous-release "20.2"
  "Version for `customize-changed-options' to refer back to by default.")

;;;###autoload
(defun customize-changed-options (since-version)
  "Customize all user option variables changed in Emacs itself.
This includes new user option variables and faces, and new
customization groups, as well as older options and faces whose default
values have changed since the previous major Emacs release.

With argument SINCE-VERSION (a string), customize all user option
variables that were added (or their meanings were changed) since that
version."

  (interactive "sCustomize options changed, since version (default all versions): ")
  (if (equal since-version "")
      (setq since-version nil)
    (unless (condition-case nil
                (numberp (read since-version))
              (error nil))
      (signal 'wrong-type-argument (list 'numberp since-version))))
  (unless since-version
    (setq since-version customize-changed-options-previous-release))
  (let ((found nil)
        (versions nil))
    (mapatoms (lambda (symbol)
                (and (or (boundp symbol)
                         ;; For variables not yet loaded.
                         (get symbol 'standard-value)
                         ;; For groups the previous test fails, this one
                         ;; could be used to determine if symbol is a
                         ;; group. Is there a better way for this?
                         (get symbol 'group-documentation))
                     (let ((version (get symbol 'custom-version)))
                       (and version
                            (or (null since-version)
                                (customize-version-lessp since-version version))
                            (if (member version versions)
                                t
                              ;;; Collect all versions that we use.
                              (push version versions))))
                     (setq found
                           ;; We have to set the right thing here,
                           ;; depending if we have a group or a
                           ;; variable.
                           (if (get  symbol 'group-documentation)
                               (cons (list symbol 'custom-group) found)
                             (cons (list symbol 'custom-variable) found))))))
    (if (not found)
        (error "No user option defaults have been changed since Emacs %s"
               since-version)
      (let ((flist nil))
        (while versions
          (push (copy-sequence
                 (cdr (assoc (car versions)  custom-versions-load-alist)))
                flist)
          (setq versions (cdr versions)))
        (put 'custom-versions-load-alist 'custom-loads
             ;; Get all the files that correspond to element from the
             ;; VERSIONS list. This could use some simplification.
             (apply 'nconc flist)))
      ;; Because we set all the files needed to be loaded as a
      ;; `custom-loads' property to `custom-versions-load-alist' this
      ;; call will actually load them.
      (custom-load-symbol 'custom-versions-load-alist)
      ;; Clean up
      (put 'custom-versions-load-alist 'custom-loads nil)
      (custom-buffer-create (custom-sort-items found t 'first)
                            "*Customize Changed Options*"))))

(defun customize-version-lessp (version1 version2)
  ;; Why are the versions strings, and given that they are, why aren't
  ;; they converted to numbers and compared as such here?  -- fx

  ;; In case someone made a mistake and left out the quotes
  ;; in the :version value.
  (if (numberp version2)
      (setq version2 (prin1-to-string version2)))
  (let (major1 major2 minor1 minor2)
    (string-match "\\([0-9]+\\)\\(\\.\\([0-9]+\\)\\)?" version1)
    (setq major1 (read (or (match-string 1 version1)
                           "0")))
    (setq minor1 (read (or (match-string 3 version1)
                           "0")))
    (string-match "\\([0-9]+\\)\\(\\.\\([0-9]+\\)\\)?" version2)
    (setq major2 (read (or (match-string 1 version2)
                           "0")))
    (setq minor2 (read (or (match-string 3 version2)
                           "0")))
    (or (< major1 major2)
        (and (= major1 major2)
             (< minor1 minor2)))))
  
;;;###autoload
(defalias 'customize-variable-other-window 'customize-option-other-window)

;;;###autoload
(defun customize-option-other-window (symbol)
  "Customize SYMBOL, which must be a user option variable.
Show the buffer in another window, but don't select it."
  (interactive (custom-variable-prompt))
  (custom-buffer-create-other-window
   (list (list symbol 'custom-variable))
   (format "*Customize Option: %s*" (custom-unlispify-tag-name symbol))))

;;;###autoload
(defun customize-face (&optional symbol)
  "Customize SYMBOL, which should be a face name or nil.
If SYMBOL is nil, customize all faces."
  (interactive (list (completing-read "Customize face: (default all) "
                                      obarray 'custom-facep t)))
  (if (or (null symbol) (and (stringp symbol) (zerop (length symbol))))
      (custom-buffer-create (custom-sort-items
                             (mapcar (lambda (symbol)
                                       (list symbol 'custom-face))
                                     (face-list))
                             t nil)
                            "*Customize Faces*")
    (when (stringp symbol)
      (setq symbol (intern symbol)))
    (unless (symbolp symbol)
      (error "Should be a symbol %S" symbol))
    (custom-buffer-create (list (list symbol 'custom-face))
                          (format "*Customize Face: %s*"
                                  (custom-unlispify-tag-name symbol)))))

;;;###autoload
(defun customize-face-other-window (&optional symbol)
  "Show customization buffer for face SYMBOL in other window."
  (interactive (list (completing-read "Customize face: "
                                      obarray 'custom-facep t)))
  (if (or (null symbol) (and (stringp symbol) (zerop (length symbol))))
      ()
    (if (stringp symbol)
        (setq symbol (intern symbol)))
    (unless (symbolp symbol)
      (error "Should be a symbol %S" symbol))
    (custom-buffer-create-other-window
     (list (list symbol 'custom-face))
     (format "*Customize Face: %s*" (custom-unlispify-tag-name symbol)))))

;;;###autoload
(defun customize-customized ()
  "Customize all user options set since the last save in this session."
  (interactive)
  (let ((found nil))
    (mapatoms (lambda (symbol)
                (and (or (get symbol 'customized-face)
                         (get symbol 'customized-face-comment))
                     (custom-facep symbol)
                     (push (list symbol 'custom-face) found))
                (and (or (get symbol 'customized-value)
                         (get symbol 'customized-variable-comment))
                     (boundp symbol)
                     (push (list symbol 'custom-variable) found))))
    (if (not found)
        (error "No customized user options")
      (custom-buffer-create (custom-sort-items found t nil)
                            "*Customize Customized*"))))

;;;###autoload
(defun customize-saved ()
  "Customize all already saved user options."
  (interactive)
  (let ((found nil))
    (mapatoms (lambda (symbol)
                (and (or (get symbol 'saved-face)
                         (get symbol 'saved-face-comment))
                     (custom-facep symbol)
                     (push (list symbol 'custom-face) found))
                (and (or (get symbol 'saved-value)
                         (get symbol 'saved-variable-comment))
                     (boundp symbol)
                     (push (list symbol 'custom-variable) found))))
    (if (not found )
        (error "No saved user options")
      (custom-buffer-create (custom-sort-items found t nil)
                            "*Customize Saved*"))))

;;;###autoload
(defun customize-apropos (regexp &optional all)
  "Customize all user options matching REGEXP.
If ALL is `options', include only options.
If ALL is `faces', include only faces.
If ALL is `groups', include only groups.
If ALL is t (interactively, with prefix arg), include options which are not
user-settable, as well as faces and groups."
  (interactive "sCustomize regexp: \nP")
  (let ((found nil))
    (mapatoms (lambda (symbol)
                (when (string-match regexp (symbol-name symbol))
                  (when (and (not (memq all '(faces options)))
                             (get symbol 'custom-group))
                    (push (list symbol 'custom-group) found))
                  (when (and (not (memq all '(options groups)))
                             (custom-facep symbol))
                    (push (list symbol 'custom-face) found))
                  (when (and (not (memq all '(groups faces)))
                             (boundp symbol)
                             (or (get symbol 'saved-value)
                                 (get symbol 'standard-value)
                                 (if (memq all '(nil options))
                                     (user-variable-p symbol)
                                   (get symbol 'variable-documentation))))
                    (push (list symbol 'custom-variable) found)))))
    (if (not found)
        (error "No matches")
      (custom-buffer-create (custom-sort-items found t
                                               custom-buffer-order-groups)
                            "*Customize Apropos*"))))

;;;###autoload
(defun customize-apropos-options (regexp &optional arg)
  "Customize all user options matching REGEXP.
With prefix arg, include options which are not user-settable."
  (interactive "sCustomize regexp: \nP")
  (customize-apropos regexp (or arg 'options)))

;;;###autoload
(defun customize-apropos-faces (regexp)
  "Customize all user faces matching REGEXP."
  (interactive "sCustomize regexp: \n")
  (customize-apropos regexp 'faces))

;;;###autoload
(defun customize-apropos-groups (regexp)
  "Customize all user groups matching REGEXP."
  (interactive "sCustomize regexp: \n")
  (customize-apropos regexp 'groups))

;;; Buffer.

(defcustom custom-buffer-style 'links
  "Control the presentation style for customization buffers.
The value should be a symbol, one of:

brackets: groups nest within each other with big horizontal brackets.
links: groups have links to subgroups."
  :type '(radio (const brackets)
                (const links))
  :group 'custom-buffer)

;; If we pass BUFFER to `bury-buffer', the buffer isn't removed from
;; the window.
(defun custom-bury-buffer (buffer)
  (bury-buffer))

(defcustom custom-buffer-done-function 'custom-bury-buffer
  "*Function called to remove a Custom buffer when the user is done with it.
Called with one argument, the buffer to remove."
  :type '(choice (function-item :tag "Bury buffer" custom-bury-buffer)
                 (function-item :tag "Kill buffer" kill-buffer)
                 (function :tag "Other"))
  :version "21.1"
  :group 'custom-buffer)

(defcustom custom-buffer-indent 3
  "Number of spaces to indent nested groups."
  :type 'integer
  :group 'custom-buffer)

;;;###autoload
(defun custom-buffer-create (options &optional name description)
  "Create a buffer containing OPTIONS.
Optional NAME is the name of the buffer.
OPTIONS should be an alist of the form ((SYMBOL WIDGET)...), where
SYMBOL is a customization option, and WIDGET is a widget for editing
that option."
  (unless name (setq name "*Customization*"))
  (kill-buffer (get-buffer-create name))
  (pop-to-buffer (get-buffer-create name))
  (custom-buffer-create-internal options description))

;;;###autoload
(defun custom-buffer-create-other-window (options &optional name description)
  "Create a buffer containing OPTIONS.
Optional NAME is the name of the buffer.
OPTIONS should be an alist of the form ((SYMBOL WIDGET)...), where
SYMBOL is a customization option, and WIDGET is a widget for editing
that option."
  (unless name (setq name "*Customization*"))
  (kill-buffer (get-buffer-create name))
  (let ((window (selected-window))
        (pop-up-windows t)
        (special-display-buffer-names nil)
        (special-display-regexps nil)
        (same-window-buffer-names nil)
        (same-window-regexps nil))
    (pop-to-buffer (get-buffer-create name))
    (custom-buffer-create-internal options description)
    (select-window window)))

(defcustom custom-reset-button-menu nil
  "If non-nil, only show a single reset button in customize buffers.
This button will have a menu with all three reset operations."
  :type 'boolean
  :group 'custom-buffer)

(defun Custom-buffer-done (&rest ignore)
  "Remove current buffer by calling `custom-buffer-done-function'."
  (interactive)
  (funcall custom-buffer-done-function (current-buffer)))

(defcustom custom-raised-buttons (not (equal (face-valid-attribute-values :box)
                                             '(("unspecified" . unspecified))))
  "If non-nil, indicate active buttons in a `raised-button' style.
Otherwise use brackets."
  :type 'boolean
  :version "21.1"
  :group 'custom-buffer)

(defun custom-buffer-create-internal (options &optional description)
  (message "Creating customization buffer...")
  (custom-mode)
  (widget-insert "This is a customization buffer")
  (if description
      (widget-insert description))
  (widget-insert (format ".
%s show active fields; type RET or click mouse-1
on an active field to invoke its action.  Editing an option value
changes the text in the buffer; invoke the State button and
choose the Set operation to set the option value.
Invoke " (if custom-raised-buttons
             "`Raised' buttons"
             "Square brackets")))
  (widget-create 'info-link
                 :tag "Help"
                 :help-echo "Read the online help."
                 "(emacs)Easy Customization")
  (widget-insert " for more information.\n\n")
  (message "Creating customization buttons...")
  (widget-insert "Operate on everything in this buffer:\n ")
  (widget-create 'push-button
                 :tag "Set for Current Session"
                 :help-echo "\
Make your editing in this buffer take effect for this session."
                 :action (lambda (widget &optional event)
                           (Custom-set)))
  (widget-insert " ")
  (widget-create 'push-button
                 :tag "Save for Future Sessions"
                 :help-echo "\
Make your editing in this buffer take effect for future Emacs sessions."
                 :action (lambda (widget &optional event)
                           (Custom-save)))
  (if custom-reset-button-menu
      (progn
        (widget-insert " ")
        (widget-create 'push-button
                       :tag "Reset"
                       :help-echo "Show a menu with reset operations."
                       :mouse-down-action (lambda (&rest junk) t)
                       :action (lambda (widget &optional event)
                                 (custom-reset event))))
    (widget-insert "\n ")
    (widget-create 'push-button
                   :tag "Reset"
                   :help-echo "\
Reset all edited text in this buffer to reflect current values."
                   :action 'Custom-reset-current)
    (widget-insert " ")
    (widget-create 'push-button
                   :tag "Reset to Saved"
                   :help-echo "\
Reset all values in this buffer to their saved settings."
                   :action 'Custom-reset-saved)
    (widget-insert " ")
    (widget-create 'push-button
                   :tag "Erase Customization"
                   :help-echo "\
Un-customize all values in this buffer.  They get their standard settings."
                   :action 'Custom-reset-standard))
  (widget-insert "   ")
  (widget-create 'push-button
                 :tag "Finish"
                 :help-echo
                 (lambda (&rest ignore)
                   (cond
                    ((eq custom-buffer-done-function
                         'custom-bury-buffer)
                     "Bury this buffer")
                    ((eq custom-buffer-done-function 'kill-buffer)
                     "Kill this buffer")
                    (t "Finish with this buffer")))
                 :action #'Custom-buffer-done)
  (widget-insert "\n\n")
  (message "Creating customization items...")
  (buffer-disable-undo)
  (setq custom-options
        (if (= (length options) 1)
            (mapcar (lambda (entry)
                      (widget-create (nth 1 entry)
                                     :documentation-shown t
                                     :custom-state 'unknown
                                     :tag (custom-unlispify-tag-name
                                           (nth 0 entry))
                                     :value (nth 0 entry)))
                    options)
          (let ((count 0)
                (length (length options)))
            (mapcar (lambda (entry)
                      (prog2
                          (message "Creating customization items ...%2d%%"
                                   (/ (* 100.0 count) length))
                          (widget-create (nth 1 entry)
                                         :tag (custom-unlispify-tag-name
                                               (nth 0 entry))
                                         :value (nth 0 entry))
                        (setq count (1+ count))
                        (unless (eq (preceding-char) ?\n)
                          (widget-insert "\n"))
                        (widget-insert "\n")))
                    options))))
  (unless (eq (preceding-char) ?\n)
    (widget-insert "\n"))
  (message "Creating customization items ...%2d%%done" 100)
  (unless (eq custom-buffer-style 'tree)
    (mapc 'custom-magic-reset custom-options))
  (message "Creating customization setup...")
  (widget-setup)
  (buffer-enable-undo)
  (goto-char (point-min))
  (message "Creating customization buffer...done"))

;;; The Tree Browser.

;;;###autoload
(defun customize-browse (&optional group)
  "Create a tree browser for the customize hierarchy."
  (interactive)
  (unless group
    (setq group 'emacs))
  (let ((name "*Customize Browser*"))
    (kill-buffer (get-buffer-create name))
    (pop-to-buffer (get-buffer-create name)))
  (custom-mode)
  (widget-insert "\
Square brackets show active fields; type RET or click mouse-1
on an active field to invoke its action.
Invoke [+] below to expand a group, and [-] to collapse an expanded group.\n")
  (if custom-browse-only-groups
      (widget-insert "\
Invoke the [Group] button below to edit that item in another window.\n\n")
    (widget-insert "Invoke the ")
    (widget-create 'item
                   :format "%t"
                   :tag "[Group]"
                   :tag-glyph "folder")
    (widget-insert ", ")
    (widget-create 'item
                   :format "%t"
                   :tag "[Face]"
                   :tag-glyph "face")
    (widget-insert ", and ")
    (widget-create 'item
                   :format "%t"
                   :tag "[Option]"
                   :tag-glyph "option")
    (widget-insert " buttons below to edit that
item in another window.\n\n"))
  (let ((custom-buffer-style 'tree))
    (widget-create 'custom-group
                   :custom-last t
                   :custom-state 'unknown
                   :tag (custom-unlispify-tag-name group)
                   :value group))
  (goto-char (point-min)))

(define-widget 'custom-browse-visibility 'item
  "Control visibility of items in the customize tree browser."
  :format "%[[%t]%]"
  :action 'custom-browse-visibility-action)

(defun custom-browse-visibility-action (widget &rest ignore)
  (let ((custom-buffer-style 'tree))
    (custom-toggle-parent widget)))

(define-widget 'custom-browse-group-tag 'push-button
  "Show parent in other window when activated."
  :tag "Group"
  :tag-glyph "folder"
  :action 'custom-browse-group-tag-action)

(defun custom-browse-group-tag-action (widget &rest ignore)
  (let ((parent (widget-get widget :parent)))
    (customize-group-other-window (widget-value parent))))

(define-widget 'custom-browse-variable-tag 'push-button
  "Show parent in other window when activated."
  :tag "Option"
  :tag-glyph "option"
  :action 'custom-browse-variable-tag-action)

(defun custom-browse-variable-tag-action (widget &rest ignore)
  (let ((parent (widget-get widget :parent)))
    (customize-variable-other-window (widget-value parent))))

(define-widget 'custom-browse-face-tag 'push-button
  "Show parent in other window when activated."
  :tag "Face"
  :tag-glyph "face"
  :action 'custom-browse-face-tag-action)

(defun custom-browse-face-tag-action (widget &rest ignore)
  (let ((parent (widget-get widget :parent)))
    (customize-face-other-window (widget-value parent))))

(defconst custom-browse-alist '(("   " "space")
                              (" | " "vertical")
                              ("-\\ " "top")
                              (" |-" "middle")
                              (" `-" "bottom")))

(defun custom-browse-insert-prefix (prefix)
  "Insert PREFIX.  On XEmacs convert it to line graphics."
  ;; Fixme: do graphics.
  (if nil ; (string-match "XEmacs" emacs-version)
      (progn
        (insert "*")
        (while (not (string-equal prefix ""))
          (let ((entry (substring prefix 0 3)))
            (setq prefix (substring prefix 3))
            (let ((overlay (make-overlay (1- (point)) (point) nil t nil))
                  (name (nth 1 (assoc entry custom-browse-alist))))
              (overlay-put overlay 'end-glyph (widget-glyph-find name entry))
              (overlay-put overlay 'start-open t)
              (overlay-put overlay 'end-open t)))))
    (insert prefix)))

;;; Modification of Basic Widgets.
;;
;; We add extra properties to the basic widgets needed here.  This is
;; fine, as long as we are careful to stay within out own namespace.
;;
;; We want simple widgets to be displayed by default, but complex
;; widgets to be hidden.

(widget-put (get 'item 'widget-type) :custom-show t)
(widget-put (get 'editable-field 'widget-type)
            :custom-show (lambda (widget value)
                           (let ((pp (pp-to-string value)))
                             (cond ((string-match "\n" pp)
                                    nil)
                                   ((> (length pp) 40)
                                    nil)
                                   (t t)))))
(widget-put (get 'menu-choice 'widget-type) :custom-show t)

;;; The `custom-manual' Widget.

(define-widget 'custom-manual 'info-link
  "Link to the manual entry for this customization option."
  :help-echo "Read the manual entry for this option."
  :tag "Manual")

;;; The `custom-magic' Widget.

(defgroup custom-magic-faces nil
  "Faces used by the magic button."
  :group 'custom-faces
  :group 'custom-buffer)

(defface custom-invalid-face '((((class color))
                                (:foreground "yellow" :background "red"))
                               (t
                                (:bold t :italic t :underline t)))
  "Face used when the customize item is invalid."
  :group 'custom-magic-faces)

(defface custom-rogue-face '((((class color))
                              (:foreground "pink" :background "black"))
                             (t
                              (:underline t)))
  "Face used when the customize item is not defined for customization."
  :group 'custom-magic-faces)

(defface custom-modified-face '((((class color))
                                 (:foreground "white" :background "blue"))
                                (t
                                 (:italic t :bold)))
  "Face used when the customize item has been modified."
  :group 'custom-magic-faces)

(defface custom-set-face '((((class color))
                                (:foreground "blue" :background "white"))
                               (t
                                (:italic t)))
  "Face used when the customize item has been set."
  :group 'custom-magic-faces)

(defface custom-changed-face '((((class color))
                                (:foreground "white" :background "blue"))
                               (t
                                (:italic t)))
  "Face used when the customize item has been changed."
  :group 'custom-magic-faces)

(defface custom-saved-face '((t (:underline t)))
  "Face used when the customize item has been saved."
  :group 'custom-magic-faces)

(defconst custom-magic-alist '((nil "#" underline "\
uninitialized, you should not see this.")
                               (unknown "?" italic "\
unknown, you should not see this.")
                               (hidden "-" default "\
hidden, invoke \"Show\" in the previous line to show." "\
group now hidden, invoke \"Show\", above, to show contents.")
                               (invalid "x" custom-invalid-face "\
the value displayed for this %c is invalid and cannot be set.")
                               (modified "*" custom-modified-face "\
you have edited the value as text, but you have not set the %c." "\
you have edited something in this group, but not set it.")
                               (set "+" custom-set-face "\
you have set this %c, but not saved it for future sessions." "\
something in this group has been set, but not saved.")
                               (changed ":" custom-changed-face "\
this %c has been changed outside the customize buffer." "\
something in this group has been changed outside customize.")
                               (saved "!" custom-saved-face "\
this %c has been set and saved." "\
something in this group has been set and saved.")
                               (rogue "@" custom-rogue-face "\
this %c has not been changed with customize." "\
something in this group is not prepared for customization.")
                               (standard " " nil "\
this %c is unchanged from its standard setting." "\
visible group members are all at standard settings."))
  "Alist of customize option states.
Each entry is of the form (STATE MAGIC FACE ITEM-DESC [ GROUP-DESC ]), where

STATE is one of the following symbols:

`nil'
   For internal use, should never occur.
`unknown'
   For internal use, should never occur.
`hidden'
   This item is not being displayed.
`invalid'
   This item is modified, but has an invalid form.
`modified'
   This item is modified, and has a valid form.
`set'
   This item has been set but not saved.
`changed'
   The current value of this item has been changed temporarily.
`saved'
   This item is marked for saving.
`rogue'
   This item has no customization information.
`standard'
   This item is unchanged from the standard setting.

MAGIC is a string used to present that state.

FACE is a face used to present the state.

ITEM-DESC is a string describing the state for options.

GROUP-DESC is a string describing the state for groups.  If this is
left out, ITEM-DESC will be used.

The string %c in either description will be replaced with the
category of the item.  These are `group'. `option', and `face'.

The list should be sorted most significant first.")

(defcustom custom-magic-show 'long
  "If non-nil, show textual description of the state.
If `long', show a full-line description, not just one word."
  :type '(choice (const :tag "no" nil)
                 (const long)
                 (other :tag "short" short))
  :group 'custom-buffer)

(defcustom custom-magic-show-hidden '(option face)
  "Control whether the State button is shown for hidden items.
The value should be a list with the custom categories where the State
button should be visible.  Possible categories are `group', `option',
and `face'."
  :type '(set (const group) (const option) (const face))
  :group 'custom-buffer)

(defcustom custom-magic-show-button nil
  "Show a \"magic\" button indicating the state of each customization option."
  :type 'boolean
  :group 'custom-buffer)

(define-widget 'custom-magic 'default
  "Show and manipulate state for a customization option."
  :format "%v"
  :action 'widget-parent-action
  :notify 'ignore
  :value-get 'ignore
  :value-create 'custom-magic-value-create
  :value-delete 'widget-children-value-delete)

(defun widget-magic-mouse-down-action (widget &optional event)
  ;; Non-nil unless hidden.
  (not (eq (widget-get (widget-get (widget-get widget :parent) :parent)
                       :custom-state)
           'hidden)))

(defun custom-magic-value-create (widget)
  "Create compact status report for WIDGET."
  (let* ((parent (widget-get widget :parent))
         (state (widget-get parent :custom-state))
         (hidden (eq state 'hidden))
         (entry (assq state custom-magic-alist))
         (magic (nth 1 entry))
         (face (nth 2 entry))
         (category (widget-get parent :custom-category))
         (text (or (and (eq category 'group)
                        (nth 4 entry))
                   (nth 3 entry)))
         (form (widget-get parent :custom-form))
         children)
    (while (string-match "\\`\\(.*\\)%c\\(.*\\)\\'" text)
      (setq text (concat (match-string 1 text)
                         (symbol-name category)
                         (match-string 2 text))))
    (when (and custom-magic-show
               (or (not hidden)
                   (memq category custom-magic-show-hidden)))
      (insert "   ")
      (when (and (eq category 'group)
                 (not (and (eq custom-buffer-style 'links)
                           (> (widget-get parent :custom-level) 1))))
        (insert-char ?\  (* custom-buffer-indent
                            (widget-get parent :custom-level))))
      (push (widget-create-child-and-convert
             widget 'choice-item
             :help-echo "Change the state of this item."
             :format (if hidden "%t" "%[%t%]")
             :button-prefix 'widget-push-button-prefix
             :button-suffix 'widget-push-button-suffix
             :mouse-down-action 'widget-magic-mouse-down-action
             :tag "State")
            children)
      (insert ": ")
      (let ((start (point)))
        (if (eq custom-magic-show 'long)
            (insert text)
          (insert (symbol-name state)))
        (cond ((eq form 'lisp)
               (insert " (lisp)"))
              ((eq form 'mismatch)
               (insert " (mismatch)")))
        (put-text-property start (point) 'face 'custom-state-face))
      (insert "\n"))
    (when (and (eq category 'group)
               (not (and (eq custom-buffer-style 'links)
                         (> (widget-get parent :custom-level) 1))))
      (insert-char ?\  (* custom-buffer-indent
                          (widget-get parent :custom-level))))
    (when custom-magic-show-button
      (when custom-magic-show
        (let ((indent (widget-get parent :indent)))
          (when indent
            (insert-char ?  indent))))
      (push (widget-create-child-and-convert
             widget 'choice-item
             :mouse-down-action 'widget-magic-mouse-down-action
             :button-face face
             :button-prefix ""
             :button-suffix ""
             :help-echo "Change the state."
             :format (if hidden "%t" "%[%t%]")
             :tag (if (memq form '(lisp mismatch))
                      (concat "(" magic ")")
                    (concat "[" magic "]")))
            children)
      (insert " "))
    (widget-put widget :children children)))

(defun custom-magic-reset (widget)
  "Redraw the :custom-magic property of WIDGET."
  (let ((magic (widget-get widget :custom-magic)))
    (widget-value-set magic (widget-value magic))))

;;; The `custom' Widget.

(defface custom-button-face
  '((((type x w32 mac) (class color))           ; Like default modeline
     (:box (:line-width 2 :style released-button)
           :background "lightgrey" :foreground "black"))
    (t
     nil))
  "Face used for buttons in customization buffers."
  :version "21.1"
  :group 'custom-faces)

(defface custom-button-pressed-face
  '((((type x w32 mac) (class color))
     (:box (:line-width 2 :style pressed-button)
           :background "lightgrey" :foreground "black"))
    (t
     (:inverse-video t)))
  "Face used for buttons in customization buffers."
  :version "21.1"
  :group 'custom-faces)

(defface custom-documentation-face nil
  "Face used for documentation strings in customization buffers."
  :group 'custom-faces)

(defface custom-state-face '((((class color)
                               (background dark))
                              (:foreground "lime green"))
                             (((class color)
                               (background light))
                              (:foreground "dark green"))
                             (t nil))
  "Face used for State descriptions in the customize buffer."
  :group 'custom-faces)

(define-widget 'custom 'default
  "Customize a user option."
  :format "%v"
  :convert-widget 'custom-convert-widget
  :notify 'custom-notify
  :custom-prefix ""
  :custom-level 1
  :custom-state 'hidden
  :documentation-property 'widget-subclass-responsibility
  :value-create 'widget-subclass-responsibility
  :value-delete 'widget-children-value-delete
  :value-get 'widget-value-value-get
  :validate 'widget-children-validate
  :match (lambda (widget value) (symbolp value)))

(defun custom-convert-widget (widget)
  "Initialize :value and :tag from :args in WIDGET."
  (let ((args (widget-get widget :args)))
    (when args
      (widget-put widget :value (widget-apply widget
                                              :value-to-internal (car args)))
      (widget-put widget :tag (custom-unlispify-tag-name (car args)))
      (widget-put widget :args nil)))
  widget)

(defun custom-notify (widget &rest args)
  "Keep track of changes."
  (let ((state (widget-get widget :custom-state)))
    (unless (eq state 'modified)
      (unless (memq state '(nil unknown hidden))
        (widget-put widget :custom-state 'modified))
      (custom-magic-reset widget)
      (apply 'widget-default-notify widget args))))

(defun custom-redraw (widget)
  "Redraw WIDGET with current settings."
  (let ((line (count-lines (point-min) (point)))
        (column (current-column))
        (pos (point))
        (from (marker-position (widget-get widget :from)))
        (to (marker-position (widget-get widget :to))))
    (save-excursion
      (widget-value-set widget (widget-value widget))
      (custom-redraw-magic widget))
    (when (and (>= pos from) (<= pos to))
      (condition-case nil
          (progn
            (if (> column 0)
                (goto-line line)
              (goto-line (1+ line)))
            (move-to-column column))
        (error nil)))))

(defun custom-redraw-magic (widget)
  "Redraw WIDGET state with current settings."
  (while widget
    (let ((magic (widget-get widget :custom-magic)))
      (cond (magic
             (widget-value-set magic (widget-value magic))
             (when (setq widget (widget-get widget :group))
               (custom-group-state-update widget)))
            (t
             (setq widget nil)))))
  (widget-setup))

(defun custom-show (widget value)
  "Non-nil if WIDGET should be shown with VALUE by default."
  (let ((show (widget-get widget :custom-show)))
    (cond ((null show)
           nil)
          ((eq t show)
           t)
          (t
           (funcall show widget value)))))

(defvar custom-load-recursion nil
  "Hack to avoid recursive dependencies.")

(defun custom-load-symbol (symbol)
  "Load all dependencies for SYMBOL."
  (unless custom-load-recursion
    (let ((custom-load-recursion t)
          (loads (get symbol 'custom-loads))
          load)
      (while loads
        (setq load (car loads)
              loads (cdr loads))
        (cond ((symbolp load)
               (condition-case nil
                   (require load)
                 (error nil)))
              ;; Don't reload a file already loaded.
              ((and (boundp 'preloaded-file-list)
                    (member load preloaded-file-list)))
              ((assoc load load-history))
              ((assoc (locate-library load) load-history))
              (t
               (condition-case nil
                   ;; Without this, we would load cus-edit recursively.
                   ;; We are still loading it when we call this,
                   ;; and it is not in load-history yet.
                   (or (equal load "cus-edit")
                       (load-library load))
                 (error nil))))))))

(defun custom-load-widget (widget)
  "Load all dependencies for WIDGET."
  (custom-load-symbol (widget-value widget)))

(defun custom-unloaded-symbol-p (symbol)
  "Return non-nil if the dependencies of SYMBOL has not yet been loaded."
  (let ((found nil)
        (loads (get symbol 'custom-loads))
        load)
    (while loads
      (setq load (car loads)
            loads (cdr loads))
      (cond ((symbolp load)
             (unless (featurep load)
               (setq found t)))
            ((assoc load load-history))
            ((assoc (locate-library load) load-history)
             (message nil))
            (t
             (setq found t))))
    found))

(defun custom-unloaded-widget-p (widget)
  "Return non-nil if the dependencies of WIDGET has not yet been loaded."
  (custom-unloaded-symbol-p (widget-value widget)))

(defun custom-toggle-hide (widget)
  "Toggle visibility of WIDGET."
  (custom-load-widget widget)
  (let ((state (widget-get widget :custom-state)))
    (cond ((memq state '(invalid modified))
           (error "There are unset changes"))
          ((eq state 'hidden)
           (widget-put widget :custom-state 'unknown))
          (t
           (widget-put widget :documentation-shown nil)
           (widget-put widget :custom-state 'hidden)))
    (custom-redraw widget)
    (widget-setup)))

(defun custom-toggle-parent (widget &rest ignore)
  "Toggle visibility of parent of WIDGET."
  (custom-toggle-hide (widget-get widget :parent)))

(defun custom-add-see-also (widget &optional prefix)
  "Add `See also ...' to WIDGET if there are any links.
Insert PREFIX first if non-nil."
  (let* ((symbol (widget-get widget :value))
         (links (get symbol 'custom-links))
         (many (> (length links) 2))
         (buttons (widget-get widget :buttons))
         (indent (widget-get widget :indent)))
    (when links
      (when indent
        (insert-char ?\  indent))
      (when prefix
        (insert prefix))
      (insert "See also ")
      (while links
        (push (widget-create-child-and-convert widget (car links))
              buttons)
        (setq links (cdr links))
        (cond ((null links)
               (insert ".\n"))
              ((null (cdr links))
               (if many
                   (insert ", and ")
                 (insert " and ")))
              (t
               (insert ", "))))
      (widget-put widget :buttons buttons))))

(defun custom-add-parent-links (widget &optional initial-string)
  "Add \"Parent groups: ...\" to WIDGET if the group has parents.
The value if non-nil if any parents were found.
If INITIAL-STRING is non-nil, use that rather than \"Parent groups:\"."
  (let ((name (widget-value widget))
        (type (widget-type widget))
        (buttons (widget-get widget :buttons))
        (start (point))
        found)
    (insert (or initial-string "Parent groups:"))
    (mapatoms (lambda (symbol)
                (let ((entry (assq name (get symbol 'custom-group))))
                  (when (eq (nth 1 entry) type)
                    (insert " ")
                    (push (widget-create-child-and-convert
                           widget 'custom-group-link
                           :tag (custom-unlispify-tag-name symbol)
                           symbol)
                          buttons)
                    (setq found t)))))
    (widget-put widget :buttons buttons)
    (if found
        (insert "\n")
      (delete-region start (point)))
    found))

;;; The `custom-comment' Widget.

;; like the editable field
(defface custom-comment-face '((((class grayscale color)
                                 (background light))
                                (:background "gray85"))
                               (((class grayscale color)
                                 (background dark))
                                (:background "dim gray"))
                               (t
                                (:italic t)))
  "Face used for comments on variables or faces"
  :version "21.1"
  :group 'custom-faces)

;; like font-lock-comment-face
(defface custom-comment-tag-face
  '((((class color) (background dark)) (:foreground "gray80"))
    (((class color) (background light)) (:foreground "blue4"))
    (((class grayscale) (background light))
     (:foreground "DimGray" :bold t :italic t))
    (((class grayscale) (background dark))
     (:foreground "LightGray" :bold t :italic t))
    (t (:bold t)))
  "Face used for variables or faces comment tags"
  :group 'custom-faces)

(define-widget 'custom-comment 'string
  "User comment."
  :tag "Comment"
  :help-echo "Edit a comment here."
  :sample-face 'custom-comment-tag-face
  :value-face 'custom-comment-face
  :shown nil
  :create 'custom-comment-create)

(defun custom-comment-create (widget)
  (let* ((null-comment (equal "" (widget-value widget))))
    (if (or (widget-get (widget-get widget :parent) :comment-shown)
            (not null-comment))
        (widget-default-create widget)
      ;; `widget-default-delete' expects markers in these slots --
      ;; maybe it shouldn't.
      (widget-put widget :from (point-marker))
      (widget-put widget :to (point-marker)))))

(defun custom-comment-hide (widget)
  (widget-put (widget-get widget :parent) :comment-shown nil))

;; Those functions are for the menu. WIDGET is NOT the comment widget. It's
;; the global custom one
(defun custom-comment-show (widget)
  (widget-put widget :comment-shown t)
  (custom-redraw widget)
  (widget-setup))

(defun custom-comment-invisible-p (widget)
  (let ((val (widget-value (widget-get widget :comment-widget))))
    (and (equal "" val)
         (not (widget-get widget :comment-shown)))))

;;; The `custom-variable' Widget.

;; When this was underlined blue, users confused it with a
;; Mosaic-style hyperlink...
(defface custom-variable-tag-face
  `((((class color)
      (background dark))
     (:foreground "light blue" :bold t :height 1.2 :inherit variable-pitch))
    (((class color)
      (background light))
     (:foreground "blue" :bold t :height 1.2 :inherit variable-pitch))
    (t (:bold t)))
  "Face used for unpushable variable tags."
  :group 'custom-faces)

(defface custom-variable-button-face '((t (:underline t :bold t)))
  "Face used for pushable variable tags."
  :group 'custom-faces)

(defcustom custom-variable-default-form 'edit
  "Default form of displaying variable values."
  :type '(choice (const edit)
                 (const lisp))
  :group 'custom-buffer
  :version "20.3")

(define-widget 'custom-variable 'custom
  "Customize variable."
  :format "%v"
  :help-echo "Set or reset this variable."
  :documentation-property 'variable-documentation
  :custom-category 'option
  :custom-state nil
  :custom-menu 'custom-variable-menu-create
  :custom-form nil ; defaults to value of `custom-variable-default-form'
  :value-create 'custom-variable-value-create
  :action 'custom-variable-action
  :custom-set 'custom-variable-set
  :custom-save 'custom-variable-save
  :custom-reset-current 'custom-redraw
  :custom-reset-saved 'custom-variable-reset-saved
  :custom-reset-standard 'custom-variable-reset-standard)

(defun custom-variable-type (symbol)
  "Return a widget suitable for editing the value of SYMBOL.
If SYMBOL has a `custom-type' property, use that.
Otherwise, look up symbol in `custom-guess-type-alist'."
  (let* ((type (or (get symbol 'custom-type)
                   (and (not (get symbol 'standard-value))
                        (custom-guess-type symbol))
                   'sexp))
         (options (get symbol 'custom-options))
         (tmp (if (listp type)
                  (copy-sequence type)
                (list type))))
    (when options
      (widget-put tmp :options options))
    tmp))

(defun custom-variable-value-create (widget)
  "Here is where you edit the variable's value."
  (custom-load-widget widget)
  (unless (widget-get widget :custom-form)
    (widget-put widget :custom-form custom-variable-default-form))
  (let* ((buttons (widget-get widget :buttons))
         (children (widget-get widget :children))
         (form (widget-get widget :custom-form))
         (state (widget-get widget :custom-state))
         (symbol (widget-get widget :value))
         (tag (widget-get widget :tag))
         (type (custom-variable-type symbol))
         (conv (widget-convert type))
         (get (or (get symbol 'custom-get) 'default-value))
         (prefix (widget-get widget :custom-prefix))
         (last (widget-get widget :custom-last))
         (value (if (default-boundp symbol)
                    (funcall get symbol)
                  (widget-get conv :value))))
    ;; If the widget is new, the child determines whether it is hidden.
    (cond (state)
          ((custom-show type value)
           (setq state 'unknown))
          (t
           (setq state 'hidden)))
    ;; If we don't know the state, see if we need to edit it in lisp form.
    (when (eq state 'unknown)
      (unless (widget-apply conv :match value)
        ;; (widget-apply (widget-convert type) :match value)
        (setq form 'mismatch)))
    ;; Now we can create the child widget.
    (cond ((eq custom-buffer-style 'tree)
           (insert prefix (if last " `--- " " |--- "))
           (push (widget-create-child-and-convert
                  widget 'custom-browse-variable-tag)
                 buttons)
           (insert " " tag "\n")
           (widget-put widget :buttons buttons))
          ((eq state 'hidden)
           ;; Indicate hidden value.
           (push (widget-create-child-and-convert
                  widget 'item
                  :format "%{%t%}: "
                  :sample-face 'custom-variable-tag-face
                  :tag tag
                  :parent widget)
                 buttons)
           (push (widget-create-child-and-convert
                  widget 'visibility
                  :help-echo "Show the value of this option."
                  :action 'custom-toggle-parent
                  nil)
                 buttons))
          ((memq form '(lisp mismatch))
           ;; In lisp mode edit the saved value when possible.
           (let* ((value (cond ((get symbol 'saved-value)
                                (car (get symbol 'saved-value)))
                               ((get symbol 'standard-value)
                                (car (get symbol 'standard-value)))
                               ((default-boundp symbol)
                                (custom-quote (funcall get symbol)))
                               (t
                                (custom-quote (widget-get conv :value))))))
             (insert (symbol-name symbol) ": ")
             (push (widget-create-child-and-convert
                    widget 'visibility
                    :help-echo "Hide the value of this option."
                    :action 'custom-toggle-parent
                    t)
                   buttons)
             (insert " ")
             (push (widget-create-child-and-convert
                    widget 'sexp
                    :button-face 'custom-variable-button-face
                    :format "%v"
                    :tag (symbol-name symbol)
                    :parent widget
                    :value value)
                   children)))
          (t
           ;; Edit mode.
           (let* ((format (widget-get type :format))
                  tag-format value-format)
             (unless (string-match ":" format)
               (error "Bad format"))
             (setq tag-format (substring format 0 (match-end 0)))
             (setq value-format (substring format (match-end 0)))
             (push (widget-create-child-and-convert
                    widget 'item
                    :format tag-format
                    :action 'custom-tag-action
                    :help-echo "Change value of this option."
                    :mouse-down-action 'custom-tag-mouse-down-action
                    :button-face 'custom-variable-button-face
                    :sample-face 'custom-variable-tag-face
                    tag)
                   buttons)
             (insert " ")
             (push (widget-create-child-and-convert
                    widget 'visibility
                    :help-echo "Hide the value of this option."
                    :action 'custom-toggle-parent
                    t)
                   buttons)
             (push (widget-create-child-and-convert
                    widget type
                    :format value-format
                    :value value)
                   children))))
    (unless (eq custom-buffer-style 'tree)
      (unless (eq (preceding-char) ?\n)
        (widget-insert "\n"))
      ;; Create the magic button.
      (let ((magic (widget-create-child-and-convert
                    widget 'custom-magic nil)))
        (widget-put widget :custom-magic magic)
        (push magic buttons))
      ;; ### NOTE: this is ugly!!!! I need to update the :buttons property
      ;; before the call to `widget-default-format-handler'. Otherwise, I
      ;; loose my current `buttons'. This function shouldn't be called like
      ;; this anyway. The doc string widget should be added like the others.
      ;; --dv
      (widget-put widget :buttons buttons)
      ;; Insert documentation.
      (widget-default-format-handler widget ?h)

      ;; The comment field
      (unless (eq state 'hidden)
        (let* ((comment (get symbol 'variable-comment))
               (comment-widget
                (widget-create-child-and-convert
                 widget 'custom-comment
                 :parent widget
                 :value (or comment ""))))
          (widget-put widget :comment-widget comment-widget)
          ;; Don't push it !!! Custom assumes that the first child is the
          ;; value one.
          (setq children (append children (list comment-widget)))))
      ;; Update the rest of the properties properties.
      (widget-put widget :custom-form form)
      (widget-put widget :children children)
      ;; Now update the state.
      (if (eq state 'hidden)
          (widget-put widget :custom-state state)
        (custom-variable-state-set widget))
      ;; See also.
      (unless (eq state 'hidden)
        (when (eq (widget-get widget :custom-level) 1)
          (custom-add-parent-links widget))
        (custom-add-see-also widget)))))

(defun custom-tag-action (widget &rest args)
  "Pass :action to first child of WIDGET's parent."
  (apply 'widget-apply (car (widget-get (widget-get widget :parent) :children))
         :action args))

(defun custom-tag-mouse-down-action (widget &rest args)
  "Pass :mouse-down-action to first child of WIDGET's parent."
  (apply 'widget-apply (car (widget-get (widget-get widget :parent) :children))
         :mouse-down-action args))

(defun custom-variable-state-set (widget)
  "Set the state of WIDGET."
  (let* ((symbol (widget-value widget))
         (get (or (get symbol 'custom-get) 'default-value))
         (value (if (default-boundp symbol)
                    (funcall get symbol)
                  (widget-get widget :value)))
         (comment (get symbol 'variable-comment))
         tmp
         temp
         (state (cond ((progn (setq tmp (get symbol 'customized-value))
                              (setq temp
                                    (get symbol 'customized-variable-comment))
                              (or tmp temp))
                       (if (condition-case nil
                               (and (equal value (eval (car tmp)))
                                    (equal comment temp))
                             (error nil))
                           'set
                         'changed))
                      ((progn (setq tmp (get symbol 'saved-value))
                              (setq temp (get symbol 'saved-variable-comment))
                              (or tmp temp))
                       (if (condition-case nil
                               (and (equal value (eval (car tmp)))
                                    (equal comment temp))
                             (error nil))
                           'saved
                         'changed))
                      ((setq tmp (get symbol 'standard-value))
                       (if (condition-case nil
                               (and (equal value (eval (car tmp)))
                                    (equal comment nil))
                             (error nil))
                           'standard
                         'changed))
                      (t 'rogue))))
    (widget-put widget :custom-state state)))

(defvar custom-variable-menu
  '(("Set for Current Session" custom-variable-set
     (lambda (widget)
       (eq (widget-get widget :custom-state) 'modified)))
    ("Save for Future Sessions" custom-variable-save
     (lambda (widget)
       (memq (widget-get widget :custom-state) '(modified set changed rogue))))
    ("Reset to Current" custom-redraw
     (lambda (widget)
       (and (default-boundp (widget-value widget))
            (memq (widget-get widget :custom-state) '(modified changed)))))
    ("Reset to Saved" custom-variable-reset-saved
     (lambda (widget)
       (and (or (get (widget-value widget) 'saved-value)
                (get (widget-value widget) 'saved-variable-comment))
            (memq (widget-get widget :custom-state)
                  '(modified set changed rogue)))))
    ("Erase Customization" custom-variable-reset-standard
     (lambda (widget)
       (and (get (widget-value widget) 'standard-value)
            (memq (widget-get widget :custom-state)
                  '(modified set changed saved rogue)))))
    ("---" ignore ignore)
    ("Add Comment" custom-comment-show custom-comment-invisible-p)
    ("---" ignore ignore)
    ("Don't show as Lisp expression" custom-variable-edit
     (lambda (widget)
       (eq (widget-get widget :custom-form) 'lisp)))
    ("Show initial Lisp expression" custom-variable-edit-lisp
     (lambda (widget)
       (eq (widget-get widget :custom-form) 'edit))))
  "Alist of actions for the `custom-variable' widget.
Each entry has the form (NAME ACTION FILTER) where NAME is the name of
the menu entry, ACTION is the function to call on the widget when the
menu is selected, and FILTER is a predicate which takes a `custom-variable'
widget as an argument, and returns non-nil if ACTION is valid on that
widget.  If FILTER is nil, ACTION is always valid.")

(defun custom-variable-action (widget &optional event)
  "Show the menu for `custom-variable' WIDGET.
Optional EVENT is the location for the menu."
  (if (eq (widget-get widget :custom-state) 'hidden)
      (custom-toggle-hide widget)
    (unless (eq (widget-get widget :custom-state) 'modified)
      (custom-variable-state-set widget))
    (custom-redraw-magic widget)
    (let* ((completion-ignore-case t)
           (answer (widget-choose (concat "Operation on "
                                          (custom-unlispify-tag-name
                                           (widget-get widget :value)))
                                  (custom-menu-filter custom-variable-menu
                                                      widget)
                                  event)))
      (if answer
          (funcall answer widget)))))

(defun custom-variable-edit (widget)
  "Edit value of WIDGET."
  (widget-put widget :custom-state 'unknown)
  (widget-put widget :custom-form 'edit)
  (custom-redraw widget))

(defun custom-variable-edit-lisp (widget)
  "Edit the Lisp representation of the value of WIDGET."
  (widget-put widget :custom-state 'unknown)
  (widget-put widget :custom-form 'lisp)
  (custom-redraw widget))

(defun custom-variable-set (widget)
  "Set the current value for the variable being edited by WIDGET."
  (let* ((form (widget-get widget :custom-form))
         (state (widget-get widget :custom-state))
         (child (car (widget-get widget :children)))
         (symbol (widget-value widget))
         (set (or (get symbol 'custom-set) 'set-default))
         (comment-widget (widget-get widget :comment-widget))
         (comment (widget-value comment-widget))
         val)
    (cond ((eq state 'hidden)
           (error "Cannot set hidden variable"))
          ((setq val (widget-apply child :validate))
           (goto-char (widget-get val :from))
           (error "%s" (widget-get val :error)))
          ((memq form '(lisp mismatch))
           (when (equal comment "")
             (setq comment nil)
             ;; Make the comment invisible by hand if it's empty
             (custom-comment-hide comment-widget))
           (funcall set symbol (eval (setq val (widget-value child))))
           (put symbol 'customized-value (list val))
           (put symbol 'variable-comment comment)
           (put symbol 'customized-variable-comment comment))
          (t
           (when (equal comment "")
             (setq comment nil)
             ;; Make the comment invisible by hand if it's empty
             (custom-comment-hide comment-widget))
           (funcall set symbol (setq val (widget-value child)))
           (put symbol 'customized-value (list (custom-quote val)))
           (put symbol 'variable-comment comment)
           (put symbol 'customized-variable-comment comment)))
    (custom-variable-state-set widget)
    (custom-redraw-magic widget)))

(defun custom-variable-save (widget)
  "Set and save the value for the variable being edited by WIDGET."
  (let* ((form (widget-get widget :custom-form))
         (state (widget-get widget :custom-state))
         (child (car (widget-get widget :children)))
         (symbol (widget-value widget))
         (set (or (get symbol 'custom-set) 'set-default))
         (comment-widget (widget-get widget :comment-widget))
         (comment (widget-value comment-widget))
         val)
    (cond ((eq state 'hidden)
           (error "Cannot set hidden variable"))
          ((setq val (widget-apply child :validate))
           (goto-char (widget-get val :from))
           (error "Saving %s: %s" symbol (widget-get val :error)))
          ((memq form '(lisp mismatch))
           (when (equal comment "")
             (setq comment nil)
             ;; Make the comment invisible by hand if it's empty
             (custom-comment-hide comment-widget))
           (put symbol 'saved-value (list (widget-value child)))
           (funcall set symbol (eval (widget-value child)))
           (put symbol 'variable-comment comment)
           (put symbol 'saved-variable-comment comment))
          (t
           (when (equal comment "")
             (setq comment nil)
             ;; Make the comment invisible by hand if it's empty
             (custom-comment-hide comment-widget))
           (put symbol 'saved-value
                (list (custom-quote (widget-value child))))
           (funcall set symbol (widget-value child))
           (put symbol 'variable-comment comment)
           (put symbol 'saved-variable-comment comment)))
    (put symbol 'customized-value nil)
    (put symbol 'customized-variable-comment nil)
    (custom-save-all)
    (custom-variable-state-set widget)
    (custom-redraw-magic widget)))

(defun custom-variable-reset-saved (widget)
  "Restore the saved value for the variable being edited by WIDGET."
  (let* ((symbol (widget-value widget))
         (set (or (get symbol 'custom-set) 'set-default))
         (value (get symbol 'saved-value))
         (comment (get symbol 'saved-variable-comment)))
    (cond ((or value comment)
           (put symbol 'variable-comment comment)
           (condition-case nil
               (funcall set symbol (eval (car value)))
             (error nil)))
          (t
           (error "No saved value for %s" symbol)))
    (put symbol 'customized-value nil)
    (put symbol 'customized-variable-comment nil)
    (widget-put widget :custom-state 'unknown)
    ;; This call will possibly make the comment invisible
    (custom-redraw widget)))

(defun custom-variable-reset-standard (widget)
  "Restore the standard setting for the variable being edited by WIDGET.
This operation eliminates any saved setting for the variable,
restoring it to the state of a variable that has never been customized."
  (let* ((symbol (widget-value widget))
         (set (or (get symbol 'custom-set) 'set-default)))
    (if (get symbol 'standard-value)
        (funcall set symbol (eval (car (get symbol 'standard-value))))
      (error "No standard setting known for %S" symbol))
    (put symbol 'variable-comment nil)
    (put symbol 'customized-value nil)
    (put symbol 'customized-variable-comment nil)
    (when (or (get symbol 'saved-value) (get symbol 'saved-variable-comment))
      (put symbol 'saved-value nil)
      (put symbol 'saved-variable-comment nil)
      (custom-save-all))
    (widget-put widget :custom-state 'unknown)
    ;; This call will possibly make the comment invisible
    (custom-redraw widget)))

;;; The `custom-face-edit' Widget.

(define-widget 'custom-face-edit 'checklist
  "Edit face attributes."
  :format "%t: %v"
  :tag "Attributes"
  :extra-offset 12
  :button-args '(:help-echo "Control whether this attribute has any effect.")
  :args (mapcar (lambda (att)
                  (list 'group
                        :inline t
                        :sibling-args (widget-get (nth 1 att) :sibling-args)
                        (list 'const :format "" :value (nth 0 att))
                        (nth 1 att)))
                custom-face-attributes))

;;; The `custom-display' Widget.

(define-widget 'custom-display 'menu-choice
  "Select a display type."
  :tag "Display"
  :value t
  :help-echo "Specify frames where the face attributes should be used."
  :args '((const :tag "all" t)
          (checklist
           :offset 0
           :extra-offset 9
           :args ((group :sibling-args (:help-echo "\
Only match the specified window systems.")
                         (const :format "Type: "
                                type)
                         (checklist :inline t
                                    :offset 0
                                    (const :format "X "
                                           :sibling-args (:help-echo "\
The X11 Window System.")
                                           x)
                                    (const :format "PM "
                                           :sibling-args (:help-echo "\
OS/2 Presentation Manager.")
                                           pm)
                                    (const :format "W32 "
                                           :sibling-args (:help-echo "\
Windows NT/9X.")
                                           w32)
                                    (const :format "DOS "
                                           :sibling-args (:help-echo "\
Plain MS-DOS.")
                                           pc)
                                    (const :format "TTY%n"
                                           :sibling-args (:help-echo "\
Plain text terminals.")
                                           tty)))
                  (group :sibling-args (:help-echo "\
Only match the frames with the specified color support.")
                         (const :format "Class: "
                                class)
                         (checklist :inline t
                                    :offset 0
                                    (const :format "Color "
                                           :sibling-args (:help-echo "\
Match color frames.")
                                           color)
                                    (const :format "Grayscale "
                                           :sibling-args (:help-echo "\
Match grayscale frames.")
                                           grayscale)
                                    (const :format "Monochrome%n"
                                           :sibling-args (:help-echo "\
Match frames with no color support.")
                                           mono)))
                  (group :sibling-args (:help-echo "\
Only match frames with the specified intensity.")
                         (const :format "\
Background brightness: "
                                background)
                         (checklist :inline t
                                    :offset 0
                                    (const :format "Light "
                                           :sibling-args (:help-echo "\
Match frames with light backgrounds.")
                                           light)
                                    (const :format "Dark\n"
                                           :sibling-args (:help-echo "\
Match frames with dark backgrounds.")
                                           dark)))))))

;;; The `custom-face' Widget.

(defface custom-face-tag-face
  `((t (:bold t :height 1.2 :inherit variable-pitch)))
  "Face used for face tags."
  :group 'custom-faces)

(defcustom custom-face-default-form 'selected
  "Default form of displaying face definition."
  :type '(choice (const all)
                 (const selected)
                 (const lisp))
  :group 'custom-buffer
  :version "20.3")

(define-widget 'custom-face 'custom
  "Customize face."
  :sample-face 'custom-face-tag-face
  :help-echo "Set or reset this face."
  :documentation-property #'face-doc-string
  :value-create 'custom-face-value-create
  :action 'custom-face-action
  :custom-category 'face
  :custom-form nil ; defaults to value of `custom-face-default-form'
  :custom-set 'custom-face-set
  :custom-save 'custom-face-save
  :custom-reset-current 'custom-redraw
  :custom-reset-saved 'custom-face-reset-saved
  :custom-reset-standard 'custom-face-reset-standard
  :custom-menu 'custom-face-menu-create)

(define-widget 'custom-face-all 'editable-list
  "An editable list of display specifications and attributes."
  :entry-format "%i %d %v"
  :insert-button-args '(:help-echo "Insert new display specification here.")
  :append-button-args '(:help-echo "Append new display specification here.")
  :delete-button-args '(:help-echo "Delete this display specification.")
  :args '((group :format "%v" custom-display custom-face-edit)))

(defconst custom-face-all (widget-convert 'custom-face-all)
  "Converted version of the `custom-face-all' widget.")

(define-widget 'custom-display-unselected 'item
  "A display specification that doesn't match the selected display."
  :match 'custom-display-unselected-match)

(defun custom-display-unselected-match (widget value)
  "Non-nil if VALUE is an unselected display specification."
  (not (face-spec-set-match-display value (selected-frame))))

(define-widget 'custom-face-selected 'group
  "Edit the attributes of the selected display in a face specification."
  :args '((repeat :format ""
                  :inline t
                  (group custom-display-unselected sexp))
          (group (sexp :format "") custom-face-edit)
          (repeat :format ""
                  :inline t
                  sexp)))

(defconst custom-face-selected (widget-convert 'custom-face-selected)
  "Converted version of the `custom-face-selected' widget.")

(defun custom-filter-face-spec (spec filter-index default-filter)
  "Return a canonicalized version of SPEC using.
FILTER-INDEX is the index in the entry for each attribute in
`custom-face-attributes' at which the appropriate filter function can be
found, and DEFAULT-FILTER is the filter to apply for attributes that
don't specify one."
  (mapcar (lambda (entry)
            ;; Filter a single face-spec entry
            (let ((tests (car entry))
                  (unfiltered-attrs
                   ;; Handle both old- and new-style attribute syntax
                   (if (listp (car (cdr entry)))
                       (car (cdr entry))
                     (cdr entry)))
                  (filtered-attrs nil))
              ;; Filter each face attribute
              (while unfiltered-attrs
                (let* ((attr (pop unfiltered-attrs))
                       (pre-filtered-value (pop unfiltered-attrs))
                       (filter
                        (or (nth filter-index (assq attr custom-face-attributes))
                            default-filter))
                       (filtered-value
                        (if filter
                            (funcall filter pre-filtered-value)
                          pre-filtered-value)))
                  (push filtered-value filtered-attrs)
                  (push attr filtered-attrs)))
              ;;
              (list tests filtered-attrs)))
          spec))

(defun custom-pre-filter-face-spec (spec)
  "Return SPEC changed as necessary for editing by the face customization widget.
SPEC must be a full face spec."
  (custom-filter-face-spec
   spec 2
   (lambda (value)
     (cond ((eq value 'unspecified) nil)
           ((eq value nil) 'off)
           (t value)))))

(defun custom-post-filter-face-spec (spec)
  "Return the customized SPEC in a form suitable for setting the face."
  (custom-filter-face-spec
   spec 3
   (lambda (value)
     (cond ((eq value nil) 'unspecified)
           ((eq value 'off) nil)
           (t value)))))

(defun custom-face-value-create (widget)
  "Create a list of the display specifications for WIDGET."
  (let ((buttons (widget-get widget :buttons))
        children
        (symbol (widget-get widget :value))
        (tag (widget-get widget :tag))
        (state (widget-get widget :custom-state))
        (begin (point))
        (is-last (widget-get widget :custom-last))
        (prefix (widget-get widget :custom-prefix)))
    (unless tag
      (setq tag (prin1-to-string symbol)))
    (cond ((eq custom-buffer-style 'tree)
           (insert prefix (if is-last " `--- " " |--- "))
           (push (widget-create-child-and-convert
                  widget 'custom-browse-face-tag)
                 buttons)
           (insert " " tag "\n")
           (widget-put widget :buttons buttons))
          (t
           ;; Create tag.
           (insert tag)
           (widget-specify-sample widget begin (point))
           (if (eq custom-buffer-style 'face)
               (insert " ")
             (if (string-match "face\\'" tag)
                 (insert ":")
               (insert " face: ")))
           ;; Sample.
           (push (widget-create-child-and-convert widget 'item
                                                  :format "(%{%t%})"
                                                  :sample-face symbol
                                                  :tag "sample")
                 buttons)
           ;; Visibility.
           (insert " ")
           (push (widget-create-child-and-convert
                  widget 'visibility
                  :help-echo "Hide or show this face."
                  :action 'custom-toggle-parent
                  (not (eq state 'hidden)))
                 buttons)
           ;; Magic.
           (insert "\n")
           (let ((magic (widget-create-child-and-convert
                         widget 'custom-magic nil)))
             (widget-put widget :custom-magic magic)
             (push magic buttons))
           ;; Update buttons.
           (widget-put widget :buttons buttons)
           ;; Insert documentation.
           (widget-default-format-handler widget ?h)
           ;; The comment field
           (unless (eq state 'hidden)
             (let* ((comment (get symbol 'face-comment))
                    (comment-widget
                     (widget-create-child-and-convert
                      widget 'custom-comment
                      :parent widget
                      :value (or comment ""))))
               (widget-put widget :comment-widget comment-widget)
               (push comment-widget children)))
           ;; See also.
           (unless (eq state 'hidden)
             (when (eq (widget-get widget :custom-level) 1)
               (custom-add-parent-links widget))
             (custom-add-see-also widget))
           ;; Editor.
           (unless (eq (preceding-char) ?\n)
             (insert "\n"))
           (unless (eq state 'hidden)
             (message "Creating face editor...")
             (custom-load-widget widget)
             (unless (widget-get widget :custom-form)
                 (widget-put widget :custom-form custom-face-default-form))
             (let* ((symbol (widget-value widget))
                    (spec (or (get symbol 'saved-face)
                              (get symbol 'face-defface-spec)
                              ;; Attempt to construct it.
                              (list (list t (custom-face-attributes-get
                                             symbol (selected-frame))))))
                    (form (widget-get widget :custom-form))
                    (indent (widget-get widget :indent))
                    edit)
               ;; If the user has changed this face in some other way,
               ;; edit it as the user has specified it.
               (if (not (face-spec-match-p symbol spec (selected-frame)))
                   (setq spec (list (list t (face-attr-construct symbol (selected-frame))))))
               (setq spec (custom-pre-filter-face-spec spec))
               (setq edit (widget-create-child-and-convert
                           widget
                           (cond ((and (eq form 'selected)
                                       (widget-apply custom-face-selected
                                                     :match spec))
                                  (when indent (insert-char ?\  indent))
                                  'custom-face-selected)
                                 ((and (not (eq form 'lisp))
                                       (widget-apply custom-face-all
                                                     :match spec))
                                  'custom-face-all)
                                 (t
                                  (when indent (insert-char ?\  indent))
                                  'sexp))
                           :value spec))
               (custom-face-state-set widget)
               (push edit children)
               (widget-put widget :children children))
             (message "Creating face editor...done"))))))

(defvar custom-face-menu
  '(("Set for Current Session" custom-face-set)
    ("Save for Future Sessions" custom-face-save-command)
    ("Reset to Saved" custom-face-reset-saved
     (lambda (widget)
       (or (get (widget-value widget) 'saved-face)
           (get (widget-value widget) 'saved-face-comment))))
    ("Erase Customization" custom-face-reset-standard
     (lambda (widget)
       (get (widget-value widget) 'face-defface-spec)))
    ("---" ignore ignore)
    ("Add Comment" custom-comment-show custom-comment-invisible-p)
    ("---" ignore ignore)
    ("Show all display specs" custom-face-edit-all
     (lambda (widget)
       (not (eq (widget-get widget :custom-form) 'all))))
    ("Just current attributes" custom-face-edit-selected
     (lambda (widget)
       (not (eq (widget-get widget :custom-form) 'selected))))
    ("Show as Lisp expression" custom-face-edit-lisp
     (lambda (widget)
       (not (eq (widget-get widget :custom-form) 'lisp)))))
  "Alist of actions for the `custom-face' widget.
Each entry has the form (NAME ACTION FILTER) where NAME is the name of
the menu entry, ACTION is the function to call on the widget when the
menu is selected, and FILTER is a predicate which takes a `custom-face'
widget as an argument, and returns non-nil if ACTION is valid on that
widget.  If FILTER is nil, ACTION is always valid.")

(defun custom-face-edit-selected (widget)
  "Edit selected attributes of the value of WIDGET."
  (widget-put widget :custom-state 'unknown)
  (widget-put widget :custom-form 'selected)
  (custom-redraw widget))

(defun custom-face-edit-all (widget)
  "Edit all attributes of the value of WIDGET."
  (widget-put widget :custom-state 'unknown)
  (widget-put widget :custom-form 'all)
  (custom-redraw widget))

(defun custom-face-edit-lisp (widget)
  "Edit the Lisp representation of the value of WIDGET."
  (widget-put widget :custom-state 'unknown)
  (widget-put widget :custom-form 'lisp)
  (custom-redraw widget))

(defun custom-face-state-set (widget)
  "Set the state of WIDGET."
  (let* ((symbol (widget-value widget))
         (comment (get symbol 'face-comment))
         tmp temp)
    (widget-put widget :custom-state
                (cond ((progn
                         (setq tmp (get symbol 'customized-face))
                         (setq temp (get symbol 'customized-face-comment))
                         (or tmp temp))
                       (if (equal temp comment)
                           'set
                         'changed))
                      ((progn
                         (setq tmp (get symbol 'saved-face))
                         (setq temp (get symbol 'saved-face-comment))
                         (or tmp temp))
                       (if (equal temp comment)
                           'saved
                         'changed))
                      ((get symbol 'face-defface-spec)
                       (if (equal comment nil)
                           'standard
                         'changed))
                      (t
                       'rogue)))))

(defun custom-face-action (widget &optional event)
  "Show the menu for `custom-face' WIDGET.
Optional EVENT is the location for the menu."
  (if (eq (widget-get widget :custom-state) 'hidden)
      (custom-toggle-hide widget)
    (let* ((completion-ignore-case t)
           (symbol (widget-get widget :value))
           (answer (widget-choose (concat "Operation on "
                                          (custom-unlispify-tag-name symbol))
                                  (custom-menu-filter custom-face-menu
                                                      widget)
                                  event)))
      (if answer
          (funcall answer widget)))))

(defun custom-face-set (widget)
  "Make the face attributes in WIDGET take effect."
  (let* ((symbol (widget-value widget))
         (child (car (widget-get widget :children)))
         (value (custom-post-filter-face-spec (widget-value child)))
         (comment-widget (widget-get widget :comment-widget))
         (comment (widget-value comment-widget)))
    (when (equal comment "")
      (setq comment nil)
      ;; Make the comment invisible by hand if it's empty
      (custom-comment-hide comment-widget))
    (put symbol 'customized-face value)
    (if (face-spec-choose value)
        (face-spec-set symbol value)
      ;; face-set-spec ignores empty attribute lists, so just give it
      ;; something harmless instead.
      (face-spec-set symbol '((t :foreground unspecified))))
    (put symbol 'customized-face-comment comment)
    (put symbol 'face-comment comment)
    (custom-face-state-set widget)
    (custom-redraw-magic widget)))

(defun custom-face-save-command (widget)
  "Save in `.emacs' the face attributes in WIDGET."
  (custom-face-save widget)
  (custom-save-all))

(defun custom-face-save (widget)
  "Prepare for saving WIDGET's face attributes, but don't write `.emacs'."
  (let* ((symbol (widget-value widget))
         (child (car (widget-get widget :children)))
         (value (custom-post-filter-face-spec (widget-value child)))
         (comment-widget (widget-get widget :comment-widget))
         (comment (widget-value comment-widget)))
    (when (equal comment "")
      (setq comment nil)
      ;; Make the comment invisible by hand if it's empty
      (custom-comment-hide comment-widget))
    (if (face-spec-choose value)
        (face-spec-set symbol value)
      ;; face-set-spec ignores empty attribute lists, so just give it
      ;; something harmless instead.
      (face-spec-set symbol '((t :foreground unspecified))))
    (put symbol 'saved-face value)
    (put symbol 'customized-face nil)
    (put symbol 'face-comment comment)
    (put symbol 'customized-face-comment nil)
    (put symbol 'saved-face-comment comment)
    (custom-save-all)
    (custom-face-state-set widget)
    (custom-redraw-magic widget)))

(defun custom-face-reset-saved (widget)
  "Restore WIDGET to the face's default attributes."
  (let* ((symbol (widget-value widget))
         (child (car (widget-get widget :children)))
         (value (get symbol 'saved-face))
         (comment (get symbol 'saved-face-comment))
         (comment-widget (widget-get widget :comment-widget)))
    (unless (or value comment)
      (error "No saved value for this face"))
    (put symbol 'customized-face nil)
    (put symbol 'customized-face-comment nil)
    (face-spec-set symbol value)
    (put symbol 'face-comment comment)
    (widget-value-set child value)
    ;; This call manages the comment visibility
    (widget-value-set comment-widget (or comment ""))
    (custom-face-state-set widget)
    (custom-redraw-magic widget)))

(defun custom-face-reset-standard (widget)
  "Restore WIDGET to the face's standard settings.
This operation eliminates any saved setting for the face,
restoring it to the state of a face that has never been customized."
  (let* ((symbol (widget-value widget))
         (child (car (widget-get widget :children)))
         (value (get symbol 'face-defface-spec))
         (comment-widget (widget-get widget :comment-widget)))
    (unless value
      (error "No standard setting for this face"))
    (put symbol 'customized-face nil)
    (put symbol 'customized-face-comment nil)
    (when (or (get symbol 'saved-face) (get symbol 'saved-face-comment))
      (put symbol 'saved-face nil)
      (put symbol 'saved-face-comment nil)
      (custom-save-all))
    (face-spec-set symbol value)
    (put symbol 'face-comment nil)
    (widget-value-set child value)
    ;; This call manages the comment visibility
    (widget-value-set comment-widget "")
    (custom-face-state-set widget)
    (custom-redraw-magic widget)))

;;; The `face' Widget.

(define-widget 'face 'default
  "Select and customize a face."
  :convert-widget 'widget-value-convert-widget
  :button-prefix 'widget-push-button-prefix
  :button-suffix 'widget-push-button-suffix
  :format "%{%t%}: %[select face%] %v"
  :tag "Face"
  :value 'default
  :value-create 'widget-face-value-create
  :value-delete 'widget-face-value-delete
  :value-get 'widget-value-value-get
  :validate 'widget-children-validate
  :action 'widget-face-action
  :match (lambda (widget value) (symbolp value)))

(defun widget-face-value-create (widget)
  "Create a `custom-face' child."
  (let* ((symbol (widget-value widget))
         (custom-buffer-style 'face)
         (child (widget-create-child-and-convert
                 widget 'custom-face
                 :custom-level nil
                 :value symbol)))
    (custom-magic-reset child)
    (setq custom-options (cons child custom-options))
    (widget-put widget :children (list child))))

(defun widget-face-value-delete (widget)
  "Remove the child from the options."
  (let ((child (car (widget-get widget :children))))
    (setq custom-options (delq child custom-options))
    (widget-children-value-delete widget)))

(defvar face-history nil
  "History of entered face names.")

(defun widget-face-action (widget &optional event)
  "Prompt for a face."
  (let ((answer (completing-read "Face: "
                                 (mapcar (lambda (face)
                                           (list (symbol-name face)))
                                         (face-list))
                                 nil nil nil
                                 'face-history)))
    (unless (zerop (length answer))
      (widget-value-set widget (intern answer))
      (widget-apply widget :notify widget event)
      (widget-setup))))

;;; The `hook' Widget.

(define-widget 'hook 'list
  "A emacs lisp hook"
  :value-to-internal (lambda (widget value)
                       (if (and value (symbolp value))
                           (list value)
                         value))
  :match (lambda (widget value)
           (or (symbolp value)
               (widget-group-match widget value)))
  ;; Avoid adding undefined functions to the hook, especially for
  ;; things like `find-file-hook' or even more basic ones, to avoid
  ;; chaos.
  :set (lambda (symbol value)
         (dolist (elt value)
           (if (fboundp elt)
               (add-hook symbol elt))))
  :convert-widget 'custom-hook-convert-widget
  :tag "Hook")

(defun custom-hook-convert-widget (widget)
  ;; Handle `:options'.
  (let* ((options (widget-get widget :options))
         (other `(editable-list :inline t
                                :entry-format "%i %d%v"
                                (function :format " %v")))
         (args (if options
                   (list `(checklist :inline t
                                     ,@(mapcar (lambda (entry)
                                                 `(function-item ,entry))
                                               options))
                         other)
                 (list other))))
    (widget-put widget :args args)
    widget))

;;; The `custom-group-link' Widget.

(define-widget 'custom-group-link 'link
  "Show parent in other window when activated."
  :help-echo "Create customization buffer for this group."
  :action 'custom-group-link-action)

(defun custom-group-link-action (widget &rest ignore)
  (customize-group (widget-value widget)))

;;; The `custom-group' Widget.

(defcustom custom-group-tag-faces nil
  ;; In XEmacs, this ought to play games with font size.
  ;; Fixme: make it do so in Emacs.
  "Face used for group tags.
The first member is used for level 1 groups, the second for level 2,
and so forth.  The remaining group tags are shown with
`custom-group-tag-face'."
  :type '(repeat face)
  :group 'custom-faces)

(defface custom-group-tag-face-1
  `((((class color)
      (background dark))
     (:foreground "pink" :bold t :height 1.2 :inherit variable-pitch))
    (((class color)
      (background light))
     (:foreground "red" :bold t :height 1.2 :inherit variable-pitch))
    (t (:bold t)))
  "Face used for group tags."
  :group 'custom-faces)

(defface custom-group-tag-face
  `((((class color)
      (background dark))
     (:foreground "light blue" :bold t :height 1.2))
    (((class color)
      (background light))
     (:foreground "blue" :bold t :height 1.2))
    (t (:bold t)))
  "Face used for low level group tags."
  :group 'custom-faces)

(define-widget 'custom-group 'custom
  "Customize group."
  :format "%v"
  :sample-face-get 'custom-group-sample-face-get
  :documentation-property 'group-documentation
  :help-echo "Set or reset all members of this group."
  :value-create 'custom-group-value-create
  :action 'custom-group-action
  :custom-category 'group
  :custom-set 'custom-group-set
  :custom-save 'custom-group-save
  :custom-reset-current 'custom-group-reset-current
  :custom-reset-saved 'custom-group-reset-saved
  :custom-reset-standard 'custom-group-reset-standard
  :custom-menu 'custom-group-menu-create)

(defun custom-group-sample-face-get (widget)
  ;; Use :sample-face.
  (or (nth (1- (widget-get widget :custom-level)) custom-group-tag-faces)
      'custom-group-tag-face))

(define-widget 'custom-group-visibility 'visibility
  "An indicator and manipulator for hidden group contents."
  :create 'custom-group-visibility-create)

(defun custom-group-visibility-create (widget)
  (let ((visible (widget-value widget)))
    (if visible
        (insert "--------")))
  (widget-default-create widget))

(defun custom-group-members (symbol groups-only)
  "Return SYMBOL's custom group members.
If GROUPS-ONLY non-nil, return only those members that are groups."
  (if (not groups-only)
      (get symbol 'custom-group)
    (let (members)
      (dolist (entry (get symbol 'custom-group))
        (when (eq (nth 1 entry) 'custom-group)
          (push entry members)))
      (nreverse members))))

(defun custom-group-value-create (widget)
  "Insert a customize group for WIDGET in the current buffer."
  (let* ((state (widget-get widget :custom-state))
         (level (widget-get widget :custom-level))
         ;; (indent (widget-get widget :indent))
         (prefix (widget-get widget :custom-prefix))
         (buttons (widget-get widget :buttons))
         (tag (widget-get widget :tag))
         (symbol (widget-value widget))
         (members (custom-group-members symbol
                                        (and (eq custom-buffer-style 'tree)
                                             custom-browse-only-groups))))
    (cond ((and (eq custom-buffer-style 'tree)
                (eq state 'hidden)
                (or members (custom-unloaded-widget-p widget)))
           (custom-browse-insert-prefix prefix)
           (push (widget-create-child-and-convert
                  widget 'custom-browse-visibility
                  ;; :tag-glyph "plus"
                  :tag "+")
                 buttons)
           (insert "-- ")
           ;; (widget-glyph-insert nil "-- " "horizontal")
           (push (widget-create-child-and-convert
                  widget 'custom-browse-group-tag)
                 buttons)
           (insert " " tag "\n")
           (widget-put widget :buttons buttons))
          ((and (eq custom-buffer-style 'tree)
                (zerop (length members)))
           (custom-browse-insert-prefix prefix)
           (insert "[ ]-- ")
           ;; (widget-glyph-insert nil "[ ]" "empty")
           ;; (widget-glyph-insert nil "-- " "horizontal")
           (push (widget-create-child-and-convert
                  widget 'custom-browse-group-tag)
                 buttons)
           (insert " " tag "\n")
           (widget-put widget :buttons buttons))
          ((eq custom-buffer-style 'tree)
           (custom-browse-insert-prefix prefix)
           (custom-load-widget widget)
           (if (zerop (length members))
               (progn
                 (custom-browse-insert-prefix prefix)
                 (insert "[ ]-- ")
                 ;; (widget-glyph-insert nil "[ ]" "empty")
                 ;; (widget-glyph-insert nil "-- " "horizontal")
                 (push (widget-create-child-and-convert
                        widget 'custom-browse-group-tag)
                       buttons)
                 (insert " " tag "\n")
                 (widget-put widget :buttons buttons))
             (push (widget-create-child-and-convert
                    widget 'custom-browse-visibility
                    ;; :tag-glyph "minus"
                    :tag "-")
                   buttons)
             (insert "-\\ ")
             ;; (widget-glyph-insert nil "-\\ " "top")
             (push (widget-create-child-and-convert
                    widget 'custom-browse-group-tag)
                   buttons)
             (insert " " tag "\n")
             (widget-put widget :buttons buttons)
             (message "Creating group...")
             (let* ((members (custom-sort-items members
                              custom-browse-sort-alphabetically
                              custom-browse-order-groups))
                    (prefixes (widget-get widget :custom-prefixes))
                    (custom-prefix-list (custom-prefix-add symbol prefixes))
                    (extra-prefix (if (widget-get widget :custom-last)
                                      "   "
                                    " | "))
                    (prefix (concat prefix extra-prefix))
                    children entry)
               (while members
                 (setq entry (car members)
                       members (cdr members))
                 (push (widget-create-child-and-convert
                        widget (nth 1 entry)
                        :group widget
                        :tag (custom-unlispify-tag-name (nth 0 entry))
                        :custom-prefixes custom-prefix-list
                        :custom-level (1+ level)
                        :custom-last (null members)
                        :value (nth 0 entry)
                        :custom-prefix prefix)
                       children))
               (widget-put widget :children (reverse children)))
             (message "Creating group...done")))
          ;; Nested style.
          ((eq state 'hidden)
           ;; Create level indicator.
           (unless (eq custom-buffer-style 'links)
             (insert-char ?\  (* custom-buffer-indent (1- level)))
             (insert "-- "))
           ;; Create tag.
           (let ((begin (point)))
             (insert tag)
             (widget-specify-sample widget begin (point)))
           (insert " group: ")
           ;; Create link/visibility indicator.
           (if (eq custom-buffer-style 'links)
               (push (widget-create-child-and-convert
                      widget 'custom-group-link
                      :tag "Go to Group"
                      symbol)
                     buttons)
             (push (widget-create-child-and-convert
                    widget 'custom-group-visibility
                    :help-echo "Show members of this group."
                    :action 'custom-toggle-parent
                    (not (eq state 'hidden)))
                   buttons))
           (insert " \n")
           ;; Create magic button.
           (let ((magic (widget-create-child-and-convert
                         widget 'custom-magic nil)))
             (widget-put widget :custom-magic magic)
             (push magic buttons))
           ;; Update buttons.
           (widget-put widget :buttons buttons)
           ;; Insert documentation.
           (if (and (eq custom-buffer-style 'links) (> level 1))
               (widget-put widget :documentation-indent 0))
           (widget-default-format-handler widget ?h))
          ;; Nested style.
          (t                            ;Visible.
           ;; Add parent groups references above the group.
           (if t    ;;; This should test that the buffer
                    ;;; was made to display a group.
               (when (eq level 1)
                 (if (custom-add-parent-links widget
                                              "Go to parent group:")
                     (insert "\n"))))
           ;; Create level indicator.
           (insert-char ?\  (* custom-buffer-indent (1- level)))
           (insert "/- ")
           ;; Create tag.
           (let ((start (point)))
             (insert tag)
             (widget-specify-sample widget start (point)))
           (insert " group: ")
           ;; Create visibility indicator.
           (unless (eq custom-buffer-style 'links)
             (insert "--------")
             (push (widget-create-child-and-convert
                    widget 'visibility
                    :help-echo "Hide members of this group."
                    :action 'custom-toggle-parent
                    (not (eq state 'hidden)))
                   buttons)
             (insert " "))
           ;; Create more dashes.
           ;; Use 76 instead of 75 to compensate for the temporary "<"
           ;; added by `widget-insert'.
           (insert-char ?- (- 76 (current-column)
                              (* custom-buffer-indent level)))
           (insert "\\\n")
           ;; Create magic button.
           (let ((magic (widget-create-child-and-convert
                         widget 'custom-magic
                         :indent 0
                         nil)))
             (widget-put widget :custom-magic magic)
             (push magic buttons))
           ;; Update buttons.
           (widget-put widget :buttons buttons)
           ;; Insert documentation.
           (widget-default-format-handler widget ?h)
           ;; Parent groups.
           (if nil  ;;; This should test that the buffer
                    ;;; was not made to display a group.
               (when (eq level 1)
                 (insert-char ?\  custom-buffer-indent)
                 (custom-add-parent-links widget)))
           (custom-add-see-also widget
                                (make-string (* custom-buffer-indent level)
                                             ?\ ))
           ;; Members.
           (message "Creating group...")
           (custom-load-widget widget)
           (let* ((members (custom-sort-items members
                                              custom-buffer-sort-alphabetically
                                              custom-buffer-order-groups))
                  (prefixes (widget-get widget :custom-prefixes))
                  (custom-prefix-list (custom-prefix-add symbol prefixes))
                  (length (length members))
                  (count 0)
                  (children (mapcar (lambda (entry)
                                      (widget-insert "\n")
                                      (message "\
Creating group members... %2d%%"
                                               (/ (* 100.0 count) length))
                                      (setq count (1+ count))
                                      (prog1
                                          (widget-create-child-and-convert
                                           widget (nth 1 entry)
                                           :group widget
                                           :tag (custom-unlispify-tag-name
                                                 (nth 0 entry))
                                           :custom-prefixes custom-prefix-list
                                           :custom-level (1+ level)
                                           :value (nth 0 entry))
                                        (unless (eq (preceding-char) ?\n)
                                          (widget-insert "\n"))))
                                    members)))
             (message "Creating group magic...")
             (mapc 'custom-magic-reset children)
             (message "Creating group state...")
             (widget-put widget :children children)
             (custom-group-state-update widget)
             (message "Creating group... done"))
           ;; End line
           (insert "\n")
           (insert-char ?\  (* custom-buffer-indent (1- level)))
           (insert "\\- " (widget-get widget :tag) " group end ")
           (insert-char ?- (- 75 (current-column) (* custom-buffer-indent level)))
           (insert "/\n")))))

(defvar custom-group-menu
  '(("Set for Current Session" custom-group-set
     (lambda (widget)
       (eq (widget-get widget :custom-state) 'modified)))
    ("Save for Future Sessions" custom-group-save
     (lambda (widget)
       (memq (widget-get widget :custom-state) '(modified set))))
    ("Reset to Current" custom-group-reset-current
     (lambda (widget)
       (memq (widget-get widget :custom-state) '(modified))))
    ("Reset to Saved" custom-group-reset-saved
     (lambda (widget)
       (memq (widget-get widget :custom-state) '(modified set))))
    ("Reset to standard setting" custom-group-reset-standard
     (lambda (widget)
       (memq (widget-get widget :custom-state) '(modified set saved)))))
  "Alist of actions for the `custom-group' widget.
Each entry has the form (NAME ACTION FILTER) where NAME is the name of
the menu entry, ACTION is the function to call on the widget when the
menu is selected, and FILTER is a predicate which takes a `custom-group'
widget as an argument, and returns non-nil if ACTION is valid on that
widget.  If FILTER is nil, ACTION is always valid.")

(defun custom-group-action (widget &optional event)
  "Show the menu for `custom-group' WIDGET.
Optional EVENT is the location for the menu."
  (if (eq (widget-get widget :custom-state) 'hidden)
      (custom-toggle-hide widget)
    (let* ((completion-ignore-case t)
           (answer (widget-choose (concat "Operation on "
                                          (custom-unlispify-tag-name
                                           (widget-get widget :value)))
                                  (custom-menu-filter custom-group-menu
                                                      widget)
                                  event)))
      (if answer
          (funcall answer widget)))))

(defun custom-group-set (widget)
  "Set changes in all modified group members."
  (let ((children (widget-get widget :children)))
    (mapc (lambda (child)
            (when (eq (widget-get child :custom-state) 'modified)
              (widget-apply child :custom-set)))
            children )))

(defun custom-group-save (widget)
  "Save all modified group members."
  (let ((children (widget-get widget :children)))
    (mapc (lambda (child)
            (when (memq (widget-get child :custom-state) '(modified set))
              (widget-apply child :custom-save)))
            children )))

(defun custom-group-reset-current (widget)
  "Reset all modified group members."
  (let ((children (widget-get widget :children)))
    (mapc (lambda (child)
            (when (eq (widget-get child :custom-state) 'modified)
              (widget-apply child :custom-reset-current)))
            children )))

(defun custom-group-reset-saved (widget)
  "Reset all modified or set group members."
  (let ((children (widget-get widget :children)))
    (mapc (lambda (child)
            (when (memq (widget-get child :custom-state) '(modified set))
              (widget-apply child :custom-reset-saved)))
            children )))

(defun custom-group-reset-standard (widget)
  "Reset all modified, set, or saved group members."
  (let ((children (widget-get widget :children)))
    (mapc (lambda (child)
            (when (memq (widget-get child :custom-state)
                        '(modified set saved))
              (widget-apply child :custom-reset-standard)))
            children )))

(defun custom-group-state-update (widget)
  "Update magic."
  (unless (eq (widget-get widget :custom-state) 'hidden)
    (let* ((children (widget-get widget :children))
           (states (mapcar (lambda (child)
                             (widget-get child :custom-state))
                           children))
           (magics custom-magic-alist)
           (found 'standard))
      (while magics
        (let ((magic (car (car magics))))
          (if (and (not (eq magic 'hidden))
                   (memq magic states))
              (setq found magic
                    magics nil)
            (setq magics (cdr magics)))))
      (widget-put widget :custom-state found)))
  (custom-magic-reset widget))

;;; The `custom-save-all' Function.
;;;###autoload
(defcustom custom-file nil
  "File used for storing customization information.
The default is nil, which means to use your init file
as specified by `user-init-file'.  If you specify some other file,
you need to explicitly load that file for the settings to take effect.

When you change this variable, look in the previous custom file
\(usually your init file) for the forms `(custom-set-variables ...)'
and `(custom-set-faces ...)', and copy them (whichever ones you find)
to the new custom file.  This will preserve your existing customizations."
  :type '(choice (const :tag "Your Emacs init file" nil) file)
  :group 'customize)

(defun custom-file ()
  "Return the file name for saving customizations."
  (setq custom-file
        (or custom-file
            user-init-file
            (read-file-name "File for customizations: "
                            "~/" nil nil ".emacs"))))

(defun custom-save-delete (symbol)
  "Visit `custom-file' and delete all calls to SYMBOL from it.
Leave point at the old location of the first such call,
or (if there were none) at the end of the buffer."
  (let ((default-major-mode))
    (set-buffer (find-file-noselect (custom-file))))
  (goto-char (point-min))
  ;; Skip all whitespace and comments.
  (while (forward-comment 1))
  (or (eobp)
      (save-excursion (forward-sexp (buffer-size)))) ; Test for scan errors.
  (let (first)
    (catch 'found
      (while t ;; We exit this loop only via throw.
        ;; Skip all whitespace and comments.
        (while (forward-comment 1))
        (let ((start (point))
              (sexp (condition-case nil
                        (read (current-buffer))
                      (end-of-file (throw 'found nil)))))
          (when (and (listp sexp)
                     (eq (car sexp) symbol))
            (delete-region start (point))
            (unless first
              (setq first (point)))))))
    (if first
        (goto-char first)
      (goto-char (point-max)))))

(defun custom-save-variables ()
  "Save all customized variables in `custom-file'."
  (save-excursion
    (custom-save-delete 'custom-set-variables)
    (let ((standard-output (current-buffer))
          (saved-list (make-list 1 0))
          sort-fold-case)
      ;; First create a sorted list of saved variables.
      (mapatoms
       (lambda (symbol)
         (if (get symbol 'saved-value)
             (nconc saved-list (list symbol)))))
      (setq saved-list (sort (cdr saved-list) 'string<))
      (unless (bolp)
        (princ "\n"))
      (princ "(custom-set-variables
  ;; custom-set-variables was added by Custom -- don't edit or cut/paste it!
  ;; Your init file should contain only one such instance.\n")
      (mapcar
       (lambda (symbol)
         (let ((value (get symbol 'saved-value))
               (requests (get symbol 'custom-requests))
               (now (not (or (get symbol 'standard-value)
                             (and (not (boundp symbol))
                                  (not (get symbol 'force-value))))))
               (comment (get symbol 'saved-variable-comment))
               sep)
           (when (or value comment)
             (unless (bolp)
               (princ "\n"))
             (princ " '(")
             (prin1 symbol)
             (princ " ")
             (prin1 (car value))
             (cond ((or now requests comment)
                    (princ " ")
                    (if now
                        (princ "t")
                      (princ "nil"))
                    (cond ((or requests comment)
                           (princ " ")
                           (if requests
                               (prin1 requests)
                             (princ "nil"))
                           (cond (comment
                                  (princ " ")
                                  (prin1 comment)
                                  (princ ")"))
                                 (t
                                  (princ ")"))))
                          (t
                           (princ ")"))))
                   (t
                    (princ ")"))))))
       saved-list)
      (if (bolp)
          (princ " "))
      (princ ")")
      (unless (looking-at "\n")
        (princ "\n")))))

(defun custom-save-faces ()
  "Save all customized faces in `custom-file'."
  (save-excursion
    (custom-save-delete 'custom-set-faces)
    (let ((standard-output (current-buffer))
          (saved-list (make-list 1 0))
          sort-fold-case)
      ;; First create a sorted list of saved faces.
      (mapatoms
       (lambda (symbol)
         (if (get symbol 'saved-face)
             (nconc saved-list (list symbol)))))
      (setq saved-list (sort (cdr saved-list) 'string<))
      ;; The default face must be first, since it affects the others.
      (if (memq 'default saved-list)
          (setq saved-list (cons 'default (delq 'default saved-list))))
      (unless (bolp)
        (princ "\n"))
      (princ "(custom-set-faces
  ;; custom-set-faces was added by Custom -- don't edit or cut/paste it!
  ;; Your init file should contain only one such instance.\n")
      (mapcar
       (lambda (symbol)
         (let ((value (get symbol 'saved-face))
               (now (not (or (get 'default 'face-defface-spec)
                             (and (not (custom-facep 'default))
                                  (not (get 'default 'force-face))))))
               (comment (get 'default 'saved-face-comment)))
           (unless (eq symbol 'default))
           ;; Don't print default face here.
           (unless (bolp)
             (princ "\n"))
           (princ " '(")
           (prin1 symbol)
           (princ " ")
           (prin1 value)
           (cond ((or now comment)
                  (princ " ")
                  (if now
                      (princ "t")
                    (princ "nil"))
                  (cond (comment
                         (princ " ")
                         (prin1 comment)
                         (princ ")"))
                        (t
                         (princ ")"))))
                 (t
                  (princ ")")))))
       saved-list)
      (if (bolp)
          (princ " "))
      (princ ")")
      (unless (looking-at "\n")
        (princ "\n")))))

;;;###autoload
(defun customize-save-customized ()
  "Save all user options which have been set in this session."
  (interactive)
  (mapatoms (lambda (symbol)
              (let ((face (get symbol 'customized-face))
                    (value (get symbol 'customized-value))
                    (face-comment (get symbol 'customized-face-comment))
                    (variable-comment
                     (get symbol 'customized-variable-comment)))
                (when face
                  (put symbol 'saved-face face)
                  (put symbol 'customized-face nil))
                (when value
                  (put symbol 'saved-value value)
                  (put symbol 'customized-value nil))
                (when variable-comment
                  (put symbol 'saved-variable-comment variable-comment)
                  (put symbol 'customized-variable-comment nil))
                (when face-comment
                  (put symbol 'saved-face-comment face-comment)
                  (put symbol 'customized-face-comment nil)))))
  ;; We really should update all custom buffers here.
  (custom-save-all))

;;;###autoload
(defun custom-save-all ()
  "Save all customizations in `custom-file'."
  (let ((inhibit-read-only t))
    (custom-save-variables)
    (custom-save-faces)
    (save-excursion
      (let ((default-major-mode nil))
        (set-buffer (find-file-noselect (custom-file))))
      (save-buffer))))

;;; The Customize Menu.

;;; Menu support

(defcustom custom-menu-nesting 2
  "Maximum nesting in custom menus."
  :type 'integer
  :group 'custom-menu)

(defun custom-face-menu-create (widget symbol)
  "Ignoring WIDGET, create a menu entry for customization face SYMBOL."
  (vector (custom-unlispify-menu-entry symbol)
          `(customize-face ',symbol)
          t))

(defun custom-variable-menu-create (widget symbol)
  "Ignoring WIDGET, create a menu entry for customization variable SYMBOL."
  (let ((type (get symbol 'custom-type)))
    (unless (listp type)
      (setq type (list type)))
    (if (and type (widget-get type :custom-menu))
        (widget-apply type :custom-menu symbol)
      (vector (custom-unlispify-menu-entry symbol)
              `(customize-variable ',symbol)
              t))))

;; Add checkboxes to boolean variable entries.
(widget-put (get 'boolean 'widget-type)
            :custom-menu (lambda (widget symbol)
                           (vector (custom-unlispify-menu-entry symbol)
                                   `(customize-variable ',symbol)
                                   ':style 'toggle
                                   ':selected symbol)))

(defun custom-group-menu-create (widget symbol)
  "Ignoring WIDGET, create a menu entry for customization group SYMBOL."
  `( ,(custom-unlispify-menu-entry symbol t)
     :filter (lambda (&rest junk)
               (cdr (custom-menu-create ',symbol)))))

;;;###autoload
(defun custom-menu-create (symbol)
  "Create menu for customization group SYMBOL.
The menu is in a format applicable to `easy-menu-define'."
  (let* ((item (vector (custom-unlispify-menu-entry symbol)
                       `(customize-group ',symbol)
                       t)))
    (if (and (or (not (boundp 'custom-menu-nesting))
                 (>= custom-menu-nesting 0))
             (< (length (get symbol 'custom-group)) widget-menu-max-size))
        (let ((custom-prefix-list (custom-prefix-add symbol
                                                     custom-prefix-list))
              (members (custom-sort-items (get symbol 'custom-group)
                                          custom-menu-sort-alphabetically
                                          custom-menu-order-groups)))
          (custom-load-symbol symbol)
          `(,(custom-unlispify-menu-entry symbol t)
            ,item
            "--"
            ,@(mapcar (lambda (entry)
                        (widget-apply (if (listp (nth 1 entry))
                                          (nth 1 entry)
                                        (list (nth 1 entry)))
                                      :custom-menu (nth 0 entry)))
                      members)))
      item)))

;;;###autoload
(defun customize-menu-create (symbol &optional name)
  "Return a customize menu for customization group SYMBOL.
If optional NAME is given, use that as the name of the menu.
Otherwise the menu will be named `Customize'.
The format is suitable for use with `easy-menu-define'."
  (unless name
    (setq name "Customize"))
  `(,name
    :filter (lambda (&rest junk)
              (custom-menu-create ',symbol))))

;;; The Custom Mode.

(defvar custom-mode-map nil
  "Keymap for `custom-mode'.")

(unless custom-mode-map
  ;; This keymap should be dense, but a dense keymap would prevent inheriting
  ;; "\r" bindings from the parent map.
  (setq custom-mode-map (make-sparse-keymap))
  (set-keymap-parent custom-mode-map widget-keymap)
  (suppress-keymap custom-mode-map)
  (define-key custom-mode-map " " 'scroll-up)
  (define-key custom-mode-map "\177" 'scroll-down)
  (define-key custom-mode-map "q" 'Custom-buffer-done)
  (define-key custom-mode-map "u" 'Custom-goto-parent)
  (define-key custom-mode-map "n" 'widget-forward)
  (define-key custom-mode-map "p" 'widget-backward)
  (define-key custom-mode-map [mouse-1] 'Custom-move-and-invoke))

(defun Custom-move-and-invoke (event)
  "Move to where you click, and if it is an active field, invoke it."
  (interactive "e")
  (mouse-set-point event)
  (if (widget-event-point event)
      (let* ((pos (widget-event-point event))
             (button (get-char-property pos 'button)))
        (if button
            (widget-button-click event)))))

(easy-menu-define Custom-mode-menu
    custom-mode-map
  "Menu used in customization buffers."
  `("Custom"
    ,(customize-menu-create 'customize)
    ["Set" Custom-set t]
    ["Save" Custom-save t]
    ["Reset to Current" Custom-reset-current t]
    ["Reset to Saved" Custom-reset-saved t]
    ["Reset to Standard Settings" Custom-reset-standard t]
    ["Info" (Info-goto-node "(emacs)Easy Customization") t]))

(defun Custom-goto-parent ()
  "Go to the parent group listed at the top of this buffer.
If several parents are listed, go to the first of them."
  (interactive)
  (save-excursion
    (goto-char (point-min))
    (if (search-forward "\nGo to parent group: " nil t)
        (let* ((button (get-char-property (point) 'button))
               (parent (downcase (widget-get  button :tag))))
          (customize-group parent)))))

(defcustom custom-mode-hook nil
  "Hook called when entering Custom mode."
  :type 'hook
  :group 'custom-buffer )

(defun custom-state-buffer-message (widget)
  (if (eq (widget-get (widget-get widget :parent) :custom-state) 'modified)
      (message "To install your edits, invoke [State] and choose the Set operation")))

(defun custom-mode ()
  "Major mode for editing customization buffers.

The following commands are available:

Move to next button or editable field.     \\[widget-forward]
Move to previous button or editable field. \\[widget-backward]
\\<widget-field-keymap>\
Complete content of editable text field.   \\[widget-complete]
\\<custom-mode-map>\
Invoke button under the mouse pointer.     \\[Custom-move-and-invoke]
Invoke button under point.                 \\[widget-button-press]
Set all modifications.                     \\[Custom-set]
Make all modifications default.            \\[Custom-save]
Reset all modified options.                \\[Custom-reset-current]
Reset all modified or set options.         \\[Custom-reset-saved]
Reset all options.                         \\[Custom-reset-standard]

Entry to this mode calls the value of `custom-mode-hook'
if that value is non-nil."
  (kill-all-local-variables)
  (setq major-mode 'custom-mode
        mode-name "Custom")
  (use-local-map custom-mode-map)
  (easy-menu-add Custom-mode-menu)
  (make-local-variable 'custom-options)
  (make-local-variable 'widget-documentation-face)
  (setq widget-documentation-face 'custom-documentation-face)
  (make-local-variable 'widget-button-face)
  (setq widget-button-face 'custom-button-face)
  (set (make-local-variable 'widget-button-pressed-face)
       'custom-button-pressed-face)
  (set (make-local-variable 'widget-mouse-face)
       'custom-button-pressed-face)     ; buttons `depress' when moused
  ;; When possible, use relief for buttons, not bracketing.  This test
  ;; may not be optimal.
  (when custom-raised-buttons
    (set (make-local-variable 'widget-push-button-prefix) "")
    (set (make-local-variable 'widget-push-button-suffix) "")
    (set (make-local-variable 'widget-link-prefix) "")
    (set (make-local-variable 'widget-link-suffix) ""))
  (add-hook 'widget-edit-functions 'custom-state-buffer-message nil t)
  (run-hooks 'custom-mode-hook))

(put 'custom-mode 'mode-class 'special)

(add-to-list
 'debug-ignored-errors
 "^No user options have changed defaults in recent Emacs versions$")

;;; The End.

(provide 'cus-edit)

;;; cus-edit.el ends here