lisp/wid-edit.el

   1 ;;; wid-edit.el --- Functions for creating and using widgets.
   2 ;;
   3 ;; Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   4 ;;
   5 ;; Author: Per Abrahamsen <abraham@dina.kvl.dk>
   6 ;; Keywords: extensions
   7 ;; Version: 1.9929
   8 ;; X-URL: http://www.dina.kvl.dk/~abraham/custom/
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software; you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation; either version 2, or (at your option)
  15 ;; any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  25 ;; Boston, MA 02111-1307, USA.
  26
  27 ;;; Commentary:
  28 ;;
  29 ;; See `widget.el'.
  30
  31 ;;; Code:
  32
  33 (require 'widget)
  34 (eval-when-compile (require 'cl))
  35
  36 ;;; Compatibility.
  37
  38 (eval-and-compile
  39   (autoload 'pp-to-string "pp")
  40   (autoload 'Info-goto-node "info")
  41
  42   (when (string-match "XEmacs" emacs-version)
  43     (condition-case nil
  44         (require 'overlay)
  45       (error (load-library "x-overlay"))))
  46
  47   (if (string-match "XEmacs" emacs-version)
  48       (defun widget-event-point (event)
  49         "Character position of the end of event if that exists, or nil."
  50         (if (mouse-event-p event)
  51             (event-point event)
  52           nil))
  53     (defun widget-event-point (event)
  54       "Character position of the end of event if that exists, or nil."
  55       (posn-point (event-end event))))
  56
  57 (defalias 'widget-read-event (if (string-match "XEmacs" emacs-version)
  58                                    'next-event
  59                                  'read-event))
  60
  61   ;; The following should go away when bundled with Emacs.
  62   (condition-case ()
  63       (require 'custom)
  64     (error nil))
  65
  66   (unless (and (featurep 'custom) (fboundp 'custom-declare-variable))
  67     ;; We have the old custom-library, hack around it!
  68     (defmacro defgroup (&rest args) nil)
  69     (defmacro defcustom (var value doc &rest args)
  70       (` (defvar (, var) (, value) (, doc))))
  71     (defmacro defface (&rest args) nil)
  72     (define-widget-keywords :prefix :tag :load :link :options :type :group)
  73     (when (fboundp 'copy-face)
  74       (copy-face 'default 'widget-documentation-face)
  75       (copy-face 'bold 'widget-button-face)
  76       (copy-face 'italic 'widget-field-face)))
  77
  78   (unless (fboundp 'button-release-event-p)
  79     ;; XEmacs function missing from Emacs.
  80     (defun button-release-event-p (event)
  81       "Non-nil if EVENT is a mouse-button-release event object."
  82       (and (eventp event)
  83            (memq (event-basic-type event) '(mouse-1 mouse-2 mouse-3))
  84            (or (memq 'click (event-modifiers event))
  85                (memq  'drag (event-modifiers event))))))
  86
  87   (unless (fboundp 'error-message-string)
  88     ;; Emacs function missing in XEmacs.
  89     (defun error-message-string (obj)
  90       "Convert an error value to an error message."
  91       (let ((buf (get-buffer-create " *error-message*")))
  92         (erase-buffer buf)
  93         (display-error obj buf)
  94         (buffer-string buf)))))
  95
  96 (when (let ((a "foo"))
  97         (put-text-property 1 2 'foo 1 a)
  98         (put-text-property 1 2 'bar 2 a)
  99         (set-text-properties 1 2 nil a)
 100         (text-properties-at 1 a))
 101   ;; XEmacs 20.2 and earlier had a buggy set-text-properties.
 102   (defun set-text-properties (start end props &optional buffer-or-string)
 103     "Completely replace properties of text from START to END.
 104 The third argument PROPS is the new property list.
 105 The optional fourth argument, BUFFER-OR-STRING,
 106 is the string or buffer containing the text."
 107     (map-extents #'(lambda (extent ignored)
 108                      (remove-text-properties
 109                       start end
 110                       (list (extent-property extent 'text-prop)
 111                             nil)
 112                       buffer-or-string)
 113                      nil)
 114                  buffer-or-string start end nil nil 'text-prop)
 115     (add-text-properties start end props buffer-or-string)))
 116
 117 ;;; Customization.
 118
 119 (defgroup widgets nil
 120   "Customization support for the Widget Library."
 121   :link '(custom-manual "(widget)Top")
 122   :link '(url-link :tag "Development Page"
 123                    "http://www.dina.kvl.dk/~abraham/custom/")
 124   :prefix "widget-"
 125   :group 'extensions
 126   :group 'hypermedia)
 127
 128 (defgroup widget-documentation nil
 129   "Options controling the display of documentation strings."
 130   :group 'widgets)
 131
 132 (defgroup widget-faces nil
 133   "Faces used by the widget library."
 134   :group 'widgets
 135   :group 'faces)
 136
 137 (defface widget-documentation-face '((((class color)
 138                                        (background dark))
 139                                       (:foreground "lime green"))
 140                                      (((class color)
 141                                        (background light))
 142                                       (:foreground "dark green"))
 143                                      (t nil))
 144   "Face used for documentation text."
 145   :group 'widget-documentation
 146   :group 'widget-faces)
 147
 148 (defface widget-button-face '((t (:bold t)))
 149   "Face used for widget buttons."
 150   :group 'widget-faces)
 151
 152 (defcustom widget-mouse-face 'highlight
 153   "Face used for widget buttons when the mouse is above them."
 154   :type 'face
 155   :group 'widget-faces)
 156
 157 (defface widget-field-face '((((class grayscale color)
 158                                (background light))
 159                               (:background "gray85"))
 160                              (((class grayscale color)
 161                                (background dark))
 162                               (:background "dim gray"))
 163                              (t
 164                               (:italic t)))
 165   "Face used for editable fields."
 166   :group 'widget-faces)
 167
 168 ;;; Utility functions.
 169 ;;
 170 ;; These are not really widget specific.
 171
 172 (defsubst widget-plist-member (plist prop)
 173   ;; Return non-nil if PLIST has the property PROP.
 174   ;; PLIST is a property list, which is a list of the form
 175   ;; (PROP1 VALUE1 PROP2 VALUE2 ...).  PROP is a symbol.
 176   ;; Unlike `plist-get', this allows you to distinguish between a missing
 177   ;; property and a property with the value nil.
 178   ;; The value is actually the tail of PLIST whose car is PROP.
 179   (while (and plist (not (eq (car plist) prop)))
 180     (setq plist (cdr (cdr plist))))
 181   plist)
 182
 183 (defun widget-princ-to-string (object)
 184   ;; Return string representation of OBJECT, any Lisp object.
 185   ;; No quoting characters are used; no delimiters are printed around
 186   ;; the contents of strings.
 187   (save-excursion
 188     (set-buffer (get-buffer-create " *widget-tmp*"))
 189     (erase-buffer)
 190     (let ((standard-output (current-buffer)))
 191       (princ object))
 192     (buffer-string)))
 193
 194 (defun widget-clear-undo ()
 195   "Clear all undo information."
 196   (buffer-disable-undo (current-buffer))
 197   (buffer-enable-undo))
 198
 199 (defcustom widget-menu-max-size 40
 200   "Largest number of items allowed in a popup-menu.
 201 Larger menus are read through the minibuffer."
 202   :group 'widgets
 203   :type 'integer)
 204
 205 (defun widget-choose (title items &optional event)
 206   "Choose an item from a list.
 207
 208 First argument TITLE is the name of the list.
 209 Second argument ITEMS is an list whose members are either
 210  (NAME . VALUE), to indicate selectable items, or just strings to
 211  indicate unselectable items.
 212 Optional third argument EVENT is an input event.
 213
 214 The user is asked to choose between each NAME from the items alist,
 215 and the VALUE of the chosen element will be returned.  If EVENT is a
 216 mouse event, and the number of elements in items is less than
 217 `widget-menu-max-size', a popup menu will be used, otherwise the
 218 minibuffer."
 219   (cond ((and (< (length items) widget-menu-max-size)
 220               event (fboundp 'x-popup-menu) window-system)
 221          ;; We are in Emacs-19, pressed by the mouse
 222          (x-popup-menu event
 223                        (list title (cons "" items))))
 224         ((and (< (length items) widget-menu-max-size)
 225               event (fboundp 'popup-menu) window-system)
 226          ;; We are in XEmacs, pressed by the mouse
 227          (let ((val (get-popup-menu-response
 228                      (cons title
 229                            (mapcar
 230                             (function
 231                              (lambda (x)
 232                                (if (stringp x)
 233                                    (vector x nil nil)
 234                                  (vector (car x) (list (car x)) t))))
 235                             items)))))
 236            (setq val (and val
 237                           (listp (event-object val))
 238                           (stringp (car-safe (event-object val)))
 239                           (car (event-object val))))
 240            (cdr (assoc val items))))
 241         (t
 242          (setq items (widget-remove-if 'stringp items))
 243          (let ((val (completing-read (concat title ": ") items nil t)))
 244            (if (stringp val)
 245                (let ((try (try-completion val items)))
 246                  (when (stringp try)
 247                    (setq val try))
 248                  (cdr (assoc val items)))
 249              nil)))))
 250
 251 (defun widget-remove-if (predictate list)
 252   (let (result (tail list))
 253     (while tail
 254       (or (funcall predictate (car tail))
 255           (setq result (cons (car tail) result)))
 256       (setq tail (cdr tail)))
 257     (nreverse result)))
 258
 259 ;;; Widget text specifications.
 260 ;;
 261 ;; These functions are for specifying text properties.
 262
 263 (defun widget-specify-none (from to)
 264   ;; Clear all text properties between FROM and TO.
 265   (set-text-properties from to nil))
 266
 267 (defun widget-specify-text (from to)
 268   ;; Default properties.
 269   (add-text-properties from to (list 'read-only t
 270                                      'front-sticky t
 271                                      'rear-nonsticky nil
 272                                      'start-open nil
 273                                      'end-open nil)))
 274
 275 (defcustom widget-field-add-space
 276   (or (< emacs-major-version 20)
 277       (and (eq emacs-major-version 20)
 278            (< emacs-minor-version 3))
 279       (not (string-match "XEmacs" emacs-version)))
 280   "Non-nil means add extra space at the end of editable text fields.
 281
 282 This is needed on all versions of Emacs, and on XEmacs before 20.3.
 283 If you don't add the space, it will become impossible to edit a zero
 284 size field."
 285   :type 'boolean
 286   :group 'widgets)
 287
 288 (defun widget-specify-field (widget from to)
 289   "Specify editable button for WIDGET between FROM and TO."
 290   (put-text-property from to 'read-only nil)
 291   ;; Terminating space is not part of the field, but necessary in
 292   ;; order for local-map to work.  Remove next sexp if local-map works
 293   ;; at the end of the overlay.
 294   (save-excursion
 295     (goto-char to)
 296     (when widget-field-add-space
 297       (insert-and-inherit " "))
 298     (setq to (point)))
 299   (if widget-field-add-space
 300       (add-text-properties (1- to) to
 301                            '(front-sticky nil start-open t read-only to))
 302     (add-text-properties to (1+ to)
 303                          '(front-sticky nil start-open t read-only to)))
 304   (add-text-properties (1- from) from
 305                        '(rear-nonsticky t end-open t read-only from))
 306   (let ((map (widget-get widget :keymap))
 307         (face (or (widget-get widget :value-face) 'widget-field-face))
 308         (help-echo (widget-get widget :help-echo))
 309         (overlay (make-overlay from to nil nil t)))
 310     (unless (or (stringp help-echo) (null help-echo))
 311       (setq help-echo 'widget-mouse-help))
 312     (widget-put widget :field-overlay overlay)
 313     (overlay-put overlay 'detachable nil)
 314     (overlay-put overlay 'field widget)
 315     (overlay-put overlay 'local-map map)
 316     (overlay-put overlay 'keymap map)
 317     (overlay-put overlay 'face face)
 318     (overlay-put overlay 'balloon-help help-echo)
 319     (overlay-put overlay 'help-echo help-echo)))
 320
 321 (defun widget-specify-button (widget from to)
 322   "Specify button for WIDGET between FROM and TO."
 323   (let ((face (widget-apply widget :button-face-get))
 324         (help-echo (widget-get widget :help-echo))
 325         (overlay (make-overlay from to nil t nil)))
 326     (widget-put widget :button-overlay overlay)
 327     (unless (or (null help-echo) (stringp help-echo))
 328       (setq help-echo 'widget-mouse-help))
 329     (overlay-put overlay 'button widget)
 330     (overlay-put overlay 'mouse-face widget-mouse-face)
 331     (overlay-put overlay 'balloon-help help-echo)
 332     (overlay-put overlay 'help-echo help-echo)
 333     (overlay-put overlay 'face face)))
 334
 335 (defun widget-mouse-help (extent)
 336   "Find mouse help string for button in extent."
 337   (let* ((widget (widget-at (extent-start-position extent)))
 338          (help-echo (and widget (widget-get widget :help-echo))))
 339     (cond ((stringp help-echo)
 340            help-echo)
 341           ((and (symbolp help-echo) (fboundp help-echo)
 342                 (stringp (setq help-echo (funcall help-echo widget))))
 343            help-echo)
 344           (t
 345            (format "(widget %S :help-echo %S)" widget help-echo)))))
 346
 347 (defun widget-specify-sample (widget from to)
 348   ;; Specify sample for WIDGET between FROM and TO.
 349   (let ((face (widget-apply widget :sample-face-get)))
 350     (when face
 351       (add-text-properties from to (list 'start-open t
 352                                          'end-open t
 353                                          'face face)))))
 354 (defun widget-specify-doc (widget from to)
 355   ;; Specify documentation for WIDGET between FROM and TO.
 356   (add-text-properties from to (list 'widget-doc widget
 357                                      'face 'widget-documentation-face)))
 358
 359 (defmacro widget-specify-insert (&rest form)
 360   ;; Execute FORM without inheriting any text properties.
 361   (`
 362    (save-restriction
 363      (let ((inhibit-read-only t)
 364            result
 365            before-change-functions
 366            after-change-functions)
 367        (insert "<>")
 368        (narrow-to-region (- (point) 2) (point))
 369        (widget-specify-none (point-min) (point-max))
 370        (goto-char (1+ (point-min)))
 371        (setq result (progn (,@ form)))
 372        (delete-region (point-min) (1+ (point-min)))
 373        (delete-region (1- (point-max)) (point-max))
 374        (goto-char (point-max))
 375        result))))
 376
 377 (defface widget-inactive-face '((((class grayscale color)
 378                                   (background dark))
 379                                  (:foreground "light gray"))
 380                                 (((class grayscale color)
 381                                   (background light))
 382                                  (:foreground "dim gray"))
 383                                 (t
 384                                  (:italic t)))
 385   "Face used for inactive widgets."
 386   :group 'widget-faces)
 387
 388 (defun widget-specify-inactive (widget from to)
 389   "Make WIDGET inactive for user modifications."
 390   (unless (widget-get widget :inactive)
 391     (let ((overlay (make-overlay from to nil t nil)))
 392       (overlay-put overlay 'face 'widget-inactive-face)
 393       ;; This is disabled, as it makes the mouse cursor change shape.
 394       ;; (overlay-put overlay 'mouse-face 'widget-inactive-face)
 395       (overlay-put overlay 'evaporate t)
 396       (overlay-put overlay 'priority 100)
 397       (overlay-put overlay (if (string-match "XEmacs" emacs-version)
 398                                'read-only
 399                              'modification-hooks) '(widget-overlay-inactive))
 400       (widget-put widget :inactive overlay))))
 401
 402 (defun widget-overlay-inactive (&rest junk)
 403   "Ignoring the arguments, signal an error."
 404   (unless inhibit-read-only
 405     (error "Attempt to modify inactive widget")))
 406
 407
 408 (defun widget-specify-active (widget)
 409   "Make WIDGET active for user modifications."
 410   (let ((inactive (widget-get widget :inactive)))
 411     (when inactive
 412       (delete-overlay inactive)
 413       (widget-put widget :inactive nil))))
 414
 415 ;;; Widget Properties.
 416
 417 (defsubst widget-type (widget)
 418   "Return the type of WIDGET, a symbol."
 419   (car widget))
 420
 421 (defun widget-put (widget property value)
 422   "In WIDGET set PROPERTY to VALUE.
 423 The value can later be retrived with `widget-get'."
 424   (setcdr widget (plist-put (cdr widget) property value)))
 425
 426 (defun widget-get (widget property)
 427   "In WIDGET, get the value of PROPERTY.
 428 The value could either be specified when the widget was created, or
 429 later with `widget-put'."
 430   (let ((missing t)
 431         value tmp)
 432     (while missing
 433       (cond ((setq tmp (widget-plist-member (cdr widget) property))
 434              (setq value (car (cdr tmp))
 435                    missing nil))
 436             ((setq tmp (car widget))
 437              (setq widget (get tmp 'widget-type)))
 438             (t
 439              (setq missing nil))))
 440     value))
 441
 442 (defun widget-get-indirect (widget property)
 443   "In WIDGET, get the value of PROPERTY.
 444 If the value is a symbol, return its binding.
 445 Otherwise, just return the value."
 446   (let ((value (widget-get widget property)))
 447     (if (symbolp value)
 448         (symbol-value value)
 449       value)))
 450
 451 (defun widget-member (widget property)
 452   "Non-nil iff there is a definition in WIDGET for PROPERTY."
 453   (cond ((widget-plist-member (cdr widget) property)
 454          t)
 455         ((car widget)
 456          (widget-member (get (car widget) 'widget-type) property))
 457         (t nil)))
 458
 459 ;;;###autoload
 460 (defun widget-apply (widget property &rest args)
 461   "Apply the value of WIDGET's PROPERTY to the widget itself.
 462 ARGS are passed as extra arguments to the function."
 463   (apply (widget-get widget property) widget args))
 464
 465 (defun widget-value (widget)
 466   "Extract the current value of WIDGET."
 467   (widget-apply widget
 468                 :value-to-external (widget-apply widget :value-get)))
 469
 470 (defun widget-value-set (widget value)
 471   "Set the current value of WIDGET to VALUE."
 472   (widget-apply widget
 473                 :value-set (widget-apply widget
 474                                          :value-to-internal value)))
 475
 476 (defun widget-match-inline (widget vals)
 477   ;; In WIDGET, match the start of VALS.
 478   (cond ((widget-get widget :inline)
 479          (widget-apply widget :match-inline vals))
 480         ((and vals
 481               (widget-apply widget :match (car vals)))
 482          (cons (list (car vals)) (cdr vals)))
 483         (t nil)))
 484
 485 (defun widget-apply-action (widget &optional event)
 486   "Apply :action in WIDGET in response to EVENT."
 487   (if (widget-apply widget :active)
 488       (widget-apply widget :action event)
 489     (error "Attempt to perform action on inactive widget")))
 490
 491 ;;; Helper functions.
 492 ;;
 493 ;; These are widget specific.
 494
 495 ;;;###autoload
 496 (defun widget-prompt-value (widget prompt &optional value unbound)
 497   "Prompt for a value matching WIDGET, using PROMPT.
 498 The current value is assumed to be VALUE, unless UNBOUND is non-nil."
 499   (unless (listp widget)
 500     (setq widget (list widget)))
 501   (setq prompt (format "[%s] %s" (widget-type widget) prompt))
 502   (setq widget (widget-convert widget))
 503   (let ((answer (widget-apply widget :prompt-value prompt value unbound)))
 504     (unless (widget-apply widget :match answer)
 505       (error "Value does not match %S type." (car widget)))
 506     answer))
 507
 508 (defun widget-get-sibling (widget)
 509   "Get the item WIDGET is assumed to toggle.
 510 This is only meaningful for radio buttons or checkboxes in a list."
 511   (let* ((parent (widget-get widget :parent))
 512          (children (widget-get parent :children))
 513          child)
 514     (catch 'child
 515       (while children
 516         (setq child (car children)
 517               children (cdr children))
 518         (when (eq (widget-get child :button) widget)
 519           (throw 'child child)))
 520       nil)))
 521
 522 (defun widget-map-buttons (function &optional buffer maparg)
 523   "Map FUNCTION over the buttons in BUFFER.
 524 FUNCTION is called with the arguments WIDGET and MAPARG.
 525
 526 If FUNCTION returns non-nil, the walk is cancelled.
 527
 528 The arguments MAPARG, and BUFFER default to nil and (current-buffer),
 529 respectively."
 530   (let ((cur (point-min))
 531         (widget nil)
 532         (parent nil)
 533         (overlays (if buffer
 534                       (save-excursion (set-buffer buffer) (overlay-lists))
 535                     (overlay-lists))))
 536     (setq overlays (append (car overlays) (cdr overlays)))
 537     (while (setq cur (pop overlays))
 538       (setq widget (overlay-get cur 'button))
 539       (if (and widget (funcall function widget maparg))
 540           (setq overlays nil)))))
 541
 542 ;;; Glyphs.
 543
 544 (defcustom widget-glyph-directory (concat data-directory "custom/")
 545   "Where widget glyphs are located.
 546 If this variable is nil, widget will try to locate the directory
 547 automatically."
 548   :group 'widgets
 549   :type 'directory)
 550
 551 (defcustom widget-glyph-enable t
 552   "If non nil, use glyphs in images when available."
 553   :group 'widgets
 554   :type 'boolean)
 555
 556 (defcustom widget-image-conversion
 557   '((xpm ".xpm") (gif ".gif") (png ".png") (jpeg ".jpg" ".jpeg")
 558     (xbm ".xbm"))
 559   "Conversion alist from image formats to file name suffixes."
 560   :group 'widgets
 561   :type '(repeat (cons :format "%v"
 562                        (symbol :tag "Image Format" unknown)
 563                        (repeat :tag "Suffixes"
 564                                (string :format "%v")))))
 565
 566 (defun widget-glyph-find (image tag)
 567   "Create a glyph corresponding to IMAGE with string TAG as fallback.
 568 IMAGE should either already be a glyph, or be a file name sans
 569 extension (xpm, xbm, gif, jpg, or png) located in
 570 `widget-glyph-directory'."
 571   (cond ((not (and image
 572                    (string-match "XEmacs" emacs-version)
 573                    widget-glyph-enable
 574                    (fboundp 'make-glyph)
 575                    (fboundp 'locate-file)
 576                    image))
 577          ;; We don't want or can't use glyphs.
 578          nil)
 579         ((and (fboundp 'glyphp)
 580               (glyphp image))
 581          ;; Already a glyph.  Use it.
 582          image)
 583         ((stringp image)
 584          ;; A string.  Look it up in relevant directories.
 585          (let* ((dirlist (list (or widget-glyph-directory
 586                                    (concat data-directory
 587                                            "custom/"))
 588                                data-directory))
 589                 (formats widget-image-conversion)
 590                 file)
 591            (while (and formats (not file))
 592              (when (valid-image-instantiator-format-p (car (car formats)))
 593                (setq file (locate-file image dirlist
 594                                        (mapconcat 'identity
 595                                                   (cdr (car formats))
 596                                                   ":"))))
 597              (unless file
 598                (setq formats (cdr formats))))
 599            (and file
 600                 ;; We create a glyph with the file as the default image
 601                 ;; instantiator, and the TAG fallback
 602                 (make-glyph (list (vector (car (car formats)) ':file file)
 603                                   (vector 'string ':data tag))))))
 604         ((valid-instantiator-p image 'image)
 605          ;; A valid image instantiator (e.g. [gif :file "somefile"] etc.)
 606          (make-glyph (list image
 607                            (vector 'string ':data tag))))
 608         ((consp image)
 609          ;; This could be virtually anything.  Let `make-glyph' sort it out.
 610          (make-glyph image))
 611         (t
 612          ;; Oh well.
 613          nil)))
 614
 615 (defun widget-glyph-insert (widget tag image &optional down inactive)
 616   "In WIDGET, insert the text TAG or, if supported, IMAGE.
 617 IMAGE should either be a glyph, an image instantiator, or an image file
 618 name sans extension (xpm, xbm, gif, jpg, or png) located in
 619 `widget-glyph-directory'.
 620
 621 Optional arguments DOWN and INACTIVE is used instead of IMAGE when the
 622 glyph is pressed or inactive, respectively.
 623
 624 WARNING: If you call this with a glyph, and you want the user to be
 625 able to invoke the glyph, make sure it is unique.  If you use the
 626 same glyph for multiple widgets, invoking any of the glyphs will
 627 cause the last created widget to be invoked.
 628
 629 Instead of an instantiator, you can also use a list of instantiators,
 630 or whatever `make-glyph' will accept.  However, in that case you must
 631 provide the fallback TAG as a part of the instantiator yourself."
 632   (let ((glyph (widget-glyph-find image tag)))
 633     (if glyph
 634         (widget-glyph-insert-glyph widget
 635                                    glyph
 636                                    (widget-glyph-find down tag)
 637                                    (widget-glyph-find inactive tag))
 638       (insert tag))))
 639
 640 (defun widget-glyph-insert-glyph (widget glyph &optional down inactive)
 641   "In WIDGET, insert GLYPH.
 642 If optional arguments DOWN and INACTIVE are given, they should be
 643 glyphs used when the widget is pushed and inactive, respectively."
 644   (set-glyph-property glyph 'widget widget)
 645   (when down
 646     (set-glyph-property down 'widget widget))
 647   (when inactive
 648     (set-glyph-property inactive 'widget widget))
 649   (insert "*")
 650   (let ((ext (make-extent (point) (1- (point))))
 651         (help-echo (widget-get widget :help-echo)))
 652     (set-extent-property ext 'invisible t)
 653     (set-extent-property ext 'start-open t)
 654     (set-extent-property ext 'end-open t)
 655     (set-extent-end-glyph ext glyph)
 656     (when help-echo
 657       (set-extent-property ext 'balloon-help help-echo)
 658       (set-extent-property ext 'help-echo help-echo)))
 659   (widget-put widget :glyph-up glyph)
 660   (when down (widget-put widget :glyph-down down))
 661   (when inactive (widget-put widget :glyph-inactive inactive)))
 662
 663 ;;; Buttons.
 664
 665 (defgroup widget-button nil
 666   "The look of various kinds of buttons."
 667   :group 'widgets)
 668
 669 (defcustom widget-button-prefix ""
 670   "String used as prefix for buttons."
 671   :type 'string
 672   :group 'widget-button)
 673
 674 (defcustom widget-button-suffix ""
 675   "String used as suffix for buttons."
 676   :type 'string
 677   :group 'widget-button)
 678
 679 ;;; Creating Widgets.
 680
 681 ;;;###autoload
 682 (defun widget-create (type &rest args)
 683   "Create widget of TYPE.
 684 The optional ARGS are additional keyword arguments."
 685   (let ((widget (apply 'widget-convert type args)))
 686     (widget-apply widget :create)
 687     widget))
 688
 689 (defun widget-create-child-and-convert (parent type &rest args)
 690   "As part of the widget PARENT, create a child widget TYPE.
 691 The child is converted, using the keyword arguments ARGS."
 692   (let ((widget (apply 'widget-convert type args)))
 693     (widget-put widget :parent parent)
 694     (unless (widget-get widget :indent)
 695       (widget-put widget :indent (+ (or (widget-get parent :indent) 0)
 696                                     (or (widget-get widget :extra-offset) 0)
 697                                     (widget-get parent :offset))))
 698     (widget-apply widget :create)
 699     widget))
 700
 701 (defun widget-create-child (parent type)
 702   "Create widget of TYPE."
 703   (let ((widget (copy-sequence type)))
 704     (widget-put widget :parent parent)
 705     (unless (widget-get widget :indent)
 706       (widget-put widget :indent (+ (or (widget-get parent :indent) 0)
 707                                     (or (widget-get widget :extra-offset) 0)
 708                                     (widget-get parent :offset))))
 709     (widget-apply widget :create)
 710     widget))
 711
 712 (defun widget-create-child-value (parent type value)
 713   "Create widget of TYPE with value VALUE."
 714   (let ((widget (copy-sequence type)))
 715     (widget-put widget :value (widget-apply widget :value-to-internal value))
 716     (widget-put widget :parent parent)
 717     (unless (widget-get widget :indent)
 718       (widget-put widget :indent (+ (or (widget-get parent :indent) 0)
 719                                     (or (widget-get widget :extra-offset) 0)
 720                                     (widget-get parent :offset))))
 721     (widget-apply widget :create)
 722     widget))
 723
 724 ;;;###autoload
 725 (defun widget-delete (widget)
 726   "Delete WIDGET."
 727   (widget-apply widget :delete))
 728
 729 (defun widget-convert (type &rest args)
 730   "Convert TYPE to a widget without inserting it in the buffer.
 731 The optional ARGS are additional keyword arguments."
 732   ;; Don't touch the type.
 733   (let* ((widget (if (symbolp type)
 734                      (list type)
 735                    (copy-sequence type)))
 736          (current widget)
 737          (keys args))
 738     ;; First set the :args keyword.
 739     (while (cdr current)                ;Look in the type.
 740       (let ((next (car (cdr current))))
 741         (if (and (symbolp next) (eq (aref (symbol-name next) 0) ?:))
 742             (setq current (cdr (cdr current)))
 743           (setcdr current (list :args (cdr current)))
 744           (setq current nil))))
 745     (while args                         ;Look in the args.
 746       (let ((next (nth 0 args)))
 747         (if (and (symbolp next) (eq (aref (symbol-name next) 0) ?:))
 748             (setq args (nthcdr 2 args))
 749           (widget-put widget :args args)
 750           (setq args nil))))
 751     ;; Then Convert the widget.
 752     (setq type widget)
 753     (while type
 754       (let ((convert-widget (plist-get (cdr type) :convert-widget)))
 755         (if convert-widget
 756             (setq widget (funcall convert-widget widget))))
 757       (setq type (get (car type) 'widget-type)))
 758     ;; Finally set the keyword args.
 759     (while keys
 760       (let ((next (nth 0 keys)))
 761         (if (and (symbolp next) (eq (aref (symbol-name next) 0) ?:))
 762             (progn
 763               (widget-put widget next (nth 1 keys))
 764               (setq keys (nthcdr 2 keys)))
 765           (setq keys nil))))
 766     ;; Convert the :value to internal format.
 767     (if (widget-member widget :value)
 768         (let ((value (widget-get widget :value)))
 769           (widget-put widget
 770                       :value (widget-apply widget :value-to-internal value))))
 771     ;; Return the newly create widget.
 772     widget))
 773
 774 (defun widget-insert (&rest args)
 775   "Call `insert' with ARGS and make the text read only."
 776   (let ((inhibit-read-only t)
 777         before-change-functions
 778         after-change-functions
 779         (from (point)))
 780     (apply 'insert args)
 781     (widget-specify-text from (point))))
 782
 783 (defun widget-convert-text (type from to
 784                                  &optional button-from button-to
 785                                  &rest args)
 786   "Return a widget of type TYPE with endpoint FROM TO.
 787 Optional ARGS are extra keyword arguments for TYPE.
 788 and TO will be used as the widgets end points. If optional arguments
 789 BUTTON-FROM and BUTTON-TO are given, these will be used as the widgets
 790 button end points.
 791 Optional ARGS are extra keyword arguments for TYPE."
 792   (let ((widget (apply 'widget-convert type :delete 'widget-leave-text args))
 793         (from (copy-marker from))
 794         (to (copy-marker to)))
 795     (widget-specify-text from to)
 796     (set-marker-insertion-type from t)
 797     (set-marker-insertion-type to nil)
 798     (widget-put widget :from from)
 799     (widget-put widget :to to)
 800     (when button-from
 801       (widget-specify-button widget button-from button-to))
 802     widget))
 803
 804 (defun widget-convert-button (type from to &rest args)
 805   "Return a widget of type TYPE with endpoint FROM TO.
 806 Optional ARGS are extra keyword arguments for TYPE.
 807 No text will be inserted to the buffer, instead the text between FROM
 808 and TO will be used as the widgets end points, as well as the widgets
 809 button end points."
 810   (apply 'widget-convert-text type from to from to args))
 811
 812 (defun widget-leave-text (widget)
 813   "Remove markers and overlays from WIDGET and its children."
 814   (let ((from (widget-get widget :from))
 815         (to (widget-get widget :to))
 816         (button (widget-get widget :button-overlay))
 817         (field (widget-get widget :field-overlay))
 818         (children (widget-get widget :children)))
 819     (set-marker from nil)
 820     (set-marker to nil)
 821     (when button
 822       (delete-overlay button))
 823     (when field
 824       (delete-overlay field))
 825     (mapcar 'widget-leave-text children)))
 826
 827 ;;; Keymap and Commands.
 828
 829 (defvar widget-keymap nil
 830   "Keymap containing useful binding for buffers containing widgets.
 831 Recommended as a parent keymap for modes using widgets.")
 832
 833 (unless widget-keymap
 834   (setq widget-keymap (make-sparse-keymap))
 835   (define-key widget-keymap "\t" 'widget-forward)
 836   (define-key widget-keymap [(shift tab)] 'widget-backward)
 837   (define-key widget-keymap [backtab] 'widget-backward)
 838   (if (string-match "XEmacs" emacs-version)
 839       (progn
 840         ;;Glyph support.
 841         (define-key widget-keymap [button1] 'widget-button1-click)
 842         (define-key widget-keymap [button2] 'widget-button-click))
 843     (define-key widget-keymap [down-mouse-2] 'widget-button-click))
 844   (define-key widget-keymap "\C-m" 'widget-button-press))
 845
 846 (defvar widget-global-map global-map
 847   "Keymap used for events the widget does not handle themselves.")
 848 (make-variable-buffer-local 'widget-global-map)
 849
 850 (defvar widget-field-keymap nil
 851   "Keymap used inside an editable field.")
 852
 853 (unless widget-field-keymap
 854   (setq widget-field-keymap (copy-keymap widget-keymap))
 855   (unless (string-match "XEmacs" (emacs-version))
 856     (define-key widget-field-keymap [menu-bar] 'nil))
 857   (define-key widget-field-keymap "\C-k" 'widget-kill-line)
 858   (define-key widget-field-keymap "\M-\t" 'widget-complete)
 859   (define-key widget-field-keymap "\C-m" 'widget-field-activate)
 860   (define-key widget-field-keymap "\C-a" 'widget-beginning-of-line)
 861   (define-key widget-field-keymap "\C-e" 'widget-end-of-line)
 862   (set-keymap-parent widget-field-keymap global-map))
 863
 864 (defvar widget-text-keymap nil
 865   "Keymap used inside a text field.")
 866
 867 (unless widget-text-keymap
 868   (setq widget-text-keymap (copy-keymap widget-keymap))
 869   (unless (string-match "XEmacs" (emacs-version))
 870     (define-key widget-text-keymap [menu-bar] 'nil))
 871   (define-key widget-text-keymap "\C-a" 'widget-beginning-of-line)
 872   (define-key widget-text-keymap "\C-e" 'widget-end-of-line)
 873   (set-keymap-parent widget-text-keymap global-map))
 874
 875 (defun widget-field-activate (pos &optional event)
 876   "Invoke the ediable field at point."
 877   (interactive "@d")
 878   (let ((field (get-char-property pos 'field)))
 879     (if field
 880         (widget-apply-action field event)
 881       (call-interactively
 882        (lookup-key widget-global-map (this-command-keys))))))
 883
 884 (defface widget-button-pressed-face
 885   '((((class color))
 886      (:foreground "red"))
 887     (t
 888      (:bold t :underline t)))
 889   "Face used for pressed buttons."
 890   :group 'widget-faces)
 891
 892 (defun widget-button-click (event)
 893   "Invoke button below mouse pointer."
 894   (interactive "@e")
 895   (cond ((and (fboundp 'event-glyph)
 896               (event-glyph event))
 897          (widget-glyph-click event))
 898         ((widget-event-point event)
 899          (let* ((pos (widget-event-point event))
 900                 (button (get-char-property pos 'button)))
 901            (if button
 902                (let* ((overlay (widget-get button :button-overlay))
 903                       (face (overlay-get overlay 'face))
 904                       (mouse-face (overlay-get overlay 'mouse-face)))
 905                  (unwind-protect
 906                      (let ((track-mouse t))
 907                        (overlay-put overlay
 908                                     'face 'widget-button-pressed-face)
 909                        (overlay-put overlay
 910                                     'mouse-face 'widget-button-pressed-face)
 911                        (unless (widget-apply button :mouse-down-action event)
 912                          (while (not (button-release-event-p event))
 913                            (setq event (widget-read-event)
 914                                  pos (widget-event-point event))
 915                            (if (and pos
 916                                     (eq (get-char-property pos 'button)
 917                                         button))
 918                                (progn
 919                                  (overlay-put overlay
 920                                               'face
 921                                               'widget-button-pressed-face)
 922                                  (overlay-put overlay
 923                                               'mouse-face
 924                                               'widget-button-pressed-face))
 925                              (overlay-put overlay 'face face)
 926                              (overlay-put overlay 'mouse-face mouse-face))))
 927                        (when (and pos
 928                                   (eq (get-char-property pos 'button) button))
 929                          (widget-apply-action button event)))
 930                    (overlay-put overlay 'face face)
 931                    (overlay-put overlay 'mouse-face mouse-face)))
 932              (let (command up)
 933                ;; Find the global command to run, and check whether it
 934                ;; is bound to an up event.
 935                (cond ((setq command     ;down event
 936                             (lookup-key widget-global-map [ button2 ])))
 937                      ((setq command     ;down event
 938                             (lookup-key widget-global-map [ down-mouse-2 ])))
 939                      ((setq command     ;up event
 940                             (lookup-key widget-global-map [ button2up ]))
 941                       (setq up t))
 942                      ((setq command     ;up event
 943                             (lookup-key widget-global-map [ mouse-2]))
 944                       (setq up t)))
 945                (when command
 946                  ;; Don't execute up events twice.
 947                  (when up
 948                    (while (not (button-release-event-p event))
 949                      (setq event (widget-read-event))))
 950                  (call-interactively command))))))
 951         (t
 952          (message "You clicked somewhere weird."))))
 953
 954 (defun widget-button1-click (event)
 955   "Invoke glyph below mouse pointer."
 956   (interactive "@e")
 957   (if (and (fboundp 'event-glyph)
 958            (event-glyph event))
 959       (widget-glyph-click event)
 960     (call-interactively (lookup-key widget-global-map (this-command-keys)))))
 961
 962 (defun widget-glyph-click (event)
 963   "Handle click on a glyph."
 964   (let* ((glyph (event-glyph event))
 965          (widget (glyph-property glyph 'widget))
 966          (extent (event-glyph-extent event))
 967          (down-glyph (or (and widget (widget-get widget :glyph-down)) glyph))
 968          (up-glyph (or (and widget (widget-get widget :glyph-up)) glyph))
 969          (last event))
 970     ;; Wait for the release.
 971     (while (not (button-release-event-p last))
 972       (if (eq extent (event-glyph-extent last))
 973           (set-extent-property extent 'end-glyph down-glyph)
 974         (set-extent-property extent 'end-glyph up-glyph))
 975       (setq last (next-event event)))
 976     ;; Release glyph.
 977     (when down-glyph
 978       (set-extent-property extent 'end-glyph up-glyph))
 979     ;; Apply widget action.
 980     (when (eq extent (event-glyph-extent last))
 981       (let ((widget (glyph-property (event-glyph event) 'widget)))
 982         (cond ((null widget)
 983                (message "You clicked on a glyph."))
 984               ((not (widget-apply widget :active))
 985                (message "This glyph is inactive."))
 986               (t
 987                (widget-apply-action widget event)))))))
 988
 989 (defun widget-button-press (pos &optional event)
 990   "Invoke button at POS."
 991   (interactive "@d")
 992   (let ((button (get-char-property pos 'button)))
 993     (if button
 994         (widget-apply-action button event)
 995       (let ((command (lookup-key widget-global-map (this-command-keys))))
 996         (when (commandp command)
 997           (call-interactively command))))))
 998
 999 (defun widget-tabable-at (&optional pos)
1000   "Return the tabable widget at POS, or nil.
1001 POS defaults to the value of (point)."
1002   (unless pos
1003     (setq pos (point)))
1004   (let ((widget (or (get-char-property (point) 'button)
1005                     (get-char-property (point) 'field))))
1006     (if widget
1007         (let ((order (widget-get widget :tab-order)))
1008           (if order
1009               (if (>= order 0)
1010                   widget
1011                 nil)
1012             widget))
1013       nil)))
1014
1015 (defun widget-move (arg)
1016   "Move point to the ARG next field or button.
1017 ARG may be negative to move backward."
1018   (or (bobp) (> arg 0) (backward-char))
1019   (let ((pos (point))
1020         (number arg)
1021         (old (widget-tabable-at))
1022         new)
1023     ;; Forward.
1024     (while (> arg 0)
1025       (if (eobp)
1026           (goto-char (point-min))
1027         (forward-char 1))
1028       (and (eq pos (point))
1029            (eq arg number)
1030            (error "No buttons or fields found"))
1031       (let ((new (widget-tabable-at)))
1032         (when new
1033           (unless (eq new old)
1034             (setq arg (1- arg))
1035             (setq old new)))))
1036     ;; Backward.
1037     (while (< arg 0)
1038       (if (bobp)
1039           (goto-char (point-max))
1040         (backward-char 1))
1041       (and (eq pos (point))
1042            (eq arg number)
1043            (error "No buttons or fields found"))
1044       (let ((new (widget-tabable-at)))
1045         (when new
1046           (unless (eq new old)
1047             (setq arg (1+ arg))))))
1048     (let ((new (widget-tabable-at)))
1049       (while (eq (widget-tabable-at) new)
1050         (backward-char)))
1051     (forward-char))
1052   (widget-echo-help (point))
1053   (run-hooks 'widget-move-hook))
1054
1055 (defun widget-forward (arg)
1056   "Move point to the next field or button.
1057 With optional ARG, move across that many fields."
1058   (interactive "p")
1059   (run-hooks 'widget-forward-hook)
1060   (widget-move arg))
1061
1062 (defun widget-backward (arg)
1063   "Move point to the previous field or button.
1064 With optional ARG, move across that many fields."
1065   (interactive "p")
1066   (run-hooks 'widget-backward-hook)
1067   (widget-move (- arg)))
1068
1069 (defun widget-beginning-of-line ()
1070   "Go to beginning of field or beginning of line, whichever is first."
1071   (interactive)
1072   (let* ((field (widget-field-find (point)))
1073          (start (and field (widget-field-start field))))
1074     (if (and start (not (eq start (point))))
1075         (goto-char start)
1076       (call-interactively 'beginning-of-line))))
1077
1078 (defun widget-end-of-line ()
1079   "Go to end of field or end of line, whichever is first."
1080   (interactive)
1081   (let* ((field (widget-field-find (point)))
1082          (end (and field (widget-field-end field))))
1083     (if (and end (not (eq end (point))))
1084         (goto-char end)
1085       (call-interactively 'end-of-line))))
1086
1087 (defun widget-kill-line ()
1088   "Kill to end of field or end of line, whichever is first."
1089   (interactive)
1090   (let* ((field (widget-field-find (point)))
1091          (newline (save-excursion (forward-line 1) (point)))
1092          (end (and field (widget-field-end field))))
1093     (if (and field (> newline end))
1094         (kill-region (point) end)
1095       (call-interactively 'kill-line))))
1096
1097 (defcustom widget-complete-field (lookup-key global-map "\M-\t")
1098   "Default function to call for completion inside fields."
1099   :options '(ispell-complete-word complete-tag lisp-complete-symbol)
1100   :type 'function
1101   :group 'widgets)
1102
1103 (defun widget-complete ()
1104   "Complete content of editable field from point.
1105 When not inside a field, move to the previous button or field."
1106   (interactive)
1107   (let ((field (widget-field-find (point))))
1108     (if field
1109         (widget-apply field :complete)
1110       (error "Not in an editable field"))))
1111
1112 ;;; Setting up the buffer.
1113
1114 (defvar widget-field-new nil)
1115 ;; List of all newly created editable fields in the buffer.
1116 (make-variable-buffer-local 'widget-field-new)
1117
1118 (defvar widget-field-list nil)
1119 ;; List of all editable fields in the buffer.
1120 (make-variable-buffer-local 'widget-field-list)
1121
1122 (defun widget-setup ()
1123   "Setup current buffer so editing string widgets works."
1124   (let ((inhibit-read-only t)
1125         (after-change-functions nil)
1126         before-change-functions
1127         field)
1128     (while widget-field-new
1129       (setq field (car widget-field-new)
1130             widget-field-new (cdr widget-field-new)
1131             widget-field-list (cons field widget-field-list))
1132       (let ((from (car (widget-get field :field-overlay)))
1133             (to (cdr (widget-get field :field-overlay))))
1134         (widget-specify-field field
1135                               (marker-position from) (marker-position to))
1136         (set-marker from nil)
1137         (set-marker to nil))))
1138   (widget-clear-undo)
1139   ;; We need to maintain text properties and size of the editing fields.
1140   (make-local-variable 'after-change-functions)
1141   (make-local-variable 'before-change-functions)
1142   (setq after-change-functions
1143         (if widget-field-list '(widget-after-change) nil))
1144   (setq before-change-functions
1145         (if widget-field-list '(widget-before-change) nil)))
1146
1147 (defvar widget-field-last nil)
1148 ;; Last field containing point.
1149 (make-variable-buffer-local 'widget-field-last)
1150
1151 (defvar widget-field-was nil)
1152 ;; The widget data before the change.
1153 (make-variable-buffer-local 'widget-field-was)
1154
1155 (defun widget-field-buffer (widget)
1156   "Return the start of WIDGET's editing field."
1157   (let ((overlay (widget-get widget :field-overlay)))
1158     (and overlay (overlay-buffer overlay))))
1159
1160 (defun widget-field-start (widget)
1161   "Return the start of WIDGET's editing field."
1162   (let ((overlay (widget-get widget :field-overlay)))
1163     (and overlay (overlay-start overlay))))
1164
1165 (defun widget-field-end (widget)
1166   "Return the end of WIDGET's editing field."
1167   (let ((overlay (widget-get widget :field-overlay)))
1168     ;; Don't subtract one if local-map works at the end of the overlay.
1169     (and overlay (if widget-field-add-space
1170                      (1- (overlay-end overlay))
1171                    (overlay-end overlay)))))
1172
1173 (defun widget-field-find (pos)
1174   "Return the field at POS.
1175 Unlike (get-char-property POS 'field) this, works with empty fields too."
1176   (let ((fields widget-field-list)
1177         field found)
1178     (while fields
1179       (setq field (car fields)
1180             fields (cdr fields))
1181       (let ((start (widget-field-start field))
1182             (end (widget-field-end field)))
1183         (when (and (<= start pos) (<= pos end))
1184           (when found
1185             (debug "Overlapping fields"))
1186           (setq found field))))
1187     found))
1188
1189 (defun widget-before-change (from &rest ignore)
1190   ;; This is how, for example, a variable changes its state to `modified'.
1191   ;; when it is being edited.
1192   (condition-case nil
1193       (let ((field (widget-field-find from)))
1194         (widget-apply field :notify field))
1195     (error (debug "Before Change"))))
1196
1197 (defun widget-after-change (from to old)
1198   ;; Adjust field size and text properties.
1199   (condition-case nil
1200       (let ((field (widget-field-find from))
1201             (other (widget-field-find to)))
1202         (when field
1203           (unless (eq field other)
1204             (debug "Change in different fields"))
1205           (let ((size (widget-get field :size))
1206                 (secret (widget-get field :secret)))
1207             (when size
1208               (let ((begin (widget-field-start field))
1209                     (end (widget-field-end field)))
1210                 (cond ((< (- end begin) size)
1211                        ;; Field too small.
1212                        (save-excursion
1213                          (goto-char end)
1214                          (insert-char ?\  (- (+ begin size) end))))
1215                       ((> (- end begin) size)
1216                        ;; Field too large and
1217                        (if (or (< (point) (+ begin size))
1218                                (> (point) end))
1219                            ;; Point is outside extra space.
1220                            (setq begin (+ begin size))
1221                          ;; Point is within the extra space.
1222                          (setq begin (point)))
1223                        (save-excursion
1224                          (goto-char end)
1225                          (while (and (eq (preceding-char) ?\ )
1226                                      (> (point) begin))
1227                            (delete-backward-char 1)))))))
1228             (when secret
1229               (let ((begin (widget-field-start field))
1230                     (end (widget-field-end field)))
1231                 (when size
1232                   (while (and (> end begin)
1233                               (eq (char-after (1- end)) ?\ ))
1234                     (setq end (1- end))))
1235                 (while (< begin end)
1236                   (let ((old (char-after begin)))
1237                     (unless (eq old secret)
1238                       (subst-char-in-region begin (1+ begin) old secret)
1239                       (put-text-property begin (1+ begin) 'secret old))
1240                     (setq begin (1+ begin)))))))
1241           (widget-apply field :notify field)))
1242     (error (debug "After Change"))))
1243
1244 ;;; Widget Functions
1245 ;;
1246 ;; These functions are used in the definition of multiple widgets.
1247
1248 (defun widget-parent-action (widget &optional event)
1249   "Tell :parent of WIDGET to handle the :action.
1250 Optional EVENT is the event that triggered the action."
1251   (widget-apply (widget-get widget :parent) :action event))
1252
1253 (defun widget-children-value-delete (widget)
1254   "Delete all :children and :buttons in WIDGET."
1255   (mapcar 'widget-delete (widget-get widget :children))
1256   (widget-put widget :children nil)
1257   (mapcar 'widget-delete (widget-get widget :buttons))
1258   (widget-put widget :buttons nil))
1259
1260 (defun widget-children-validate (widget)
1261   "All the :children must be valid."
1262   (let ((children (widget-get widget :children))
1263         child found)
1264     (while (and children (not found))
1265       (setq child (car children)
1266             children (cdr children)
1267             found (widget-apply child :validate)))
1268     found))
1269
1270 (defun widget-types-convert-widget (widget)
1271   "Convert :args as widget types in WIDGET."
1272   (widget-put widget :args (mapcar 'widget-convert (widget-get widget :args)))
1273   widget)
1274
1275 (defun widget-value-convert-widget (widget)
1276   "Initialize :value from :args in WIDGET."
1277   (let ((args (widget-get widget :args)))
1278     (when args
1279       (widget-put widget :value (car args))
1280       ;; Don't convert :value here, as this is done in `widget-convert'.
1281       ;; (widget-put widget :value (widget-apply widget
1282       ;;                                      :value-to-internal (car args)))
1283       (widget-put widget :args nil)))
1284   widget)
1285
1286 (defun widget-value-value-get (widget)
1287   "Return the :value property of WIDGET."
1288   (widget-get widget :value))
1289
1290 ;;; The `default' Widget.
1291
1292 (define-widget 'default nil
1293   "Basic widget other widgets are derived from."
1294   :value-to-internal (lambda (widget value) value)
1295   :value-to-external (lambda (widget value) value)
1296   :button-prefix 'widget-button-prefix
1297   :button-suffix 'widget-button-suffix
1298   :complete 'widget-default-complete
1299   :create 'widget-default-create
1300   :indent nil
1301   :offset 0
1302   :format-handler 'widget-default-format-handler
1303   :button-face-get 'widget-default-button-face-get
1304   :sample-face-get 'widget-default-sample-face-get
1305   :delete 'widget-default-delete
1306   :value-set 'widget-default-value-set
1307   :value-inline 'widget-default-value-inline
1308   :menu-tag-get 'widget-default-menu-tag-get
1309   :validate (lambda (widget) nil)
1310   :active 'widget-default-active
1311   :activate 'widget-specify-active
1312   :deactivate 'widget-default-deactivate
1313   :mouse-down-action (lambda (widget event) nil)
1314   :action 'widget-default-action
1315   :notify 'widget-default-notify
1316   :prompt-value 'widget-default-prompt-value)
1317
1318 (defun widget-default-complete (widget)
1319   "Call the value of the :complete-function property of WIDGET.
1320 If that does not exists, call the value of `widget-complete-field'."
1321   (let ((fun (widget-get widget :complete-function)))
1322     (call-interactively (or fun widget-complete-field))))
1323
1324 (defun widget-default-create (widget)
1325   "Create WIDGET at point in the current buffer."
1326   (widget-specify-insert
1327    (let ((from (point))
1328          button-begin button-end
1329          sample-begin sample-end
1330          doc-begin doc-end
1331          value-pos)
1332      (insert (widget-get widget :format))
1333      (goto-char from)
1334      ;; Parse escapes in format.
1335      (while (re-search-forward "%\\(.\\)" nil t)
1336        (let ((escape (aref (match-string 1) 0)))
1337          (replace-match "" t t)
1338          (cond ((eq escape ?%)
1339                 (insert "%"))
1340                ((eq escape ?\[)
1341                 (setq button-begin (point))
1342                 (insert (widget-get-indirect widget :button-prefix)))
1343                ((eq escape ?\])
1344                 (insert (widget-get-indirect widget :button-suffix))
1345                 (setq button-end (point)))
1346                ((eq escape ?\{)
1347                 (setq sample-begin (point)))
1348                ((eq escape ?\})
1349                 (setq sample-end (point)))
1350                ((eq escape ?n)
1351                 (when (widget-get widget :indent)
1352                   (insert "\n")
1353                   (insert-char ?  (widget-get widget :indent))))
1354                ((eq escape ?t)
1355                 (let ((glyph (widget-get widget :tag-glyph))
1356                       (tag (widget-get widget :tag)))
1357                   (cond (glyph
1358                          (widget-glyph-insert widget (or tag "image") glyph))
1359                         (tag
1360                          (insert tag))
1361                         (t
1362                          (let ((standard-output (current-buffer)))
1363                            (princ (widget-get widget :value)))))))
1364                ((eq escape ?d)
1365                 (let ((doc (widget-get widget :doc)))
1366                   (when doc
1367                     (setq doc-begin (point))
1368                     (insert doc)
1369                     (while (eq (preceding-char) ?\n)
1370                       (delete-backward-char 1))
1371                     (insert "\n")
1372                     (setq doc-end (point)))))
1373                ((eq escape ?v)
1374                 (if (and button-begin (not button-end))
1375                     (widget-apply widget :value-create)
1376                   (setq value-pos (point))))
1377                (t
1378                 (widget-apply widget :format-handler escape)))))
1379      ;; Specify button, sample, and doc, and insert value.
1380      (and button-begin button-end
1381           (widget-specify-button widget button-begin button-end))
1382      (and sample-begin sample-end
1383           (widget-specify-sample widget sample-begin sample-end))
1384      (and doc-begin doc-end
1385           (widget-specify-doc widget doc-begin doc-end))
1386      (when value-pos
1387        (goto-char value-pos)
1388        (widget-apply widget :value-create)))
1389    (let ((from (copy-marker (point-min)))
1390          (to (copy-marker (point-max))))
1391      (widget-specify-text from to)
1392      (set-marker-insertion-type from t)
1393      (set-marker-insertion-type to nil)
1394      (widget-put widget :from from)
1395      (widget-put widget :to to)))
1396   (widget-clear-undo))
1397
1398 (defun widget-default-format-handler (widget escape)
1399   ;; We recognize the %h escape by default.
1400   (let* ((buttons (widget-get widget :buttons)))
1401     (cond ((eq escape ?h)
1402            (let* ((doc-property (widget-get widget :documentation-property))
1403                   (doc-try (cond ((widget-get widget :doc))
1404                                  ((symbolp doc-property)
1405                                   (documentation-property
1406                                    (widget-get widget :value)
1407                                    doc-property))
1408                                  (t
1409                                   (funcall doc-property
1410                                            (widget-get widget :value)))))
1411                   (doc-text (and (stringp doc-try)
1412                                  (> (length doc-try) 1)
1413                                  doc-try))
1414                   (doc-indent (widget-get widget :documentation-indent)))
1415              (when doc-text
1416                (and (eq (preceding-char) ?\n)
1417                     (widget-get widget :indent)
1418                     (insert-char ?  (widget-get widget :indent)))
1419                ;; The `*' in the beginning is redundant.
1420                (when (eq (aref doc-text  0) ?*)
1421                  (setq doc-text (substring doc-text 1)))
1422                ;; Get rid of trailing newlines.
1423                (when (string-match "\n+\\'" doc-text)
1424                  (setq doc-text (substring doc-text 0 (match-beginning 0))))
1425                (push (widget-create-child-and-convert
1426                       widget 'documentation-string
1427                       :indent (cond ((numberp doc-indent )
1428                                      doc-indent)
1429                                     ((null doc-indent)
1430                                      nil)
1431                                     (t 0))
1432                       doc-text)
1433                      buttons))))
1434           (t
1435            (error "Unknown escape `%c'" escape)))
1436     (widget-put widget :buttons buttons)))
1437
1438 (defun widget-default-button-face-get (widget)
1439   ;; Use :button-face or widget-button-face
1440   (or (widget-get widget :button-face) 'widget-button-face))
1441
1442 (defun widget-default-sample-face-get (widget)
1443   ;; Use :sample-face.
1444   (widget-get widget :sample-face))
1445
1446 (defun widget-default-delete (widget)
1447   ;; Remove widget from the buffer.
1448   (let ((from (widget-get widget :from))
1449         (to (widget-get widget :to))
1450         (inactive-overlay (widget-get widget :inactive))
1451         (button-overlay (widget-get widget :button-overlay))
1452         before-change-functions
1453         after-change-functions
1454         (inhibit-read-only t))
1455     (widget-apply widget :value-delete)
1456     (when inactive-overlay
1457       (delete-overlay inactive-overlay))
1458     (when button-overlay
1459       (delete-overlay button-overlay))
1460     (when (< from to)
1461       ;; Kludge: this doesn't need to be true for empty formats.
1462       (delete-region from to))
1463     (set-marker from nil)
1464     (set-marker to nil))
1465   (widget-clear-undo))
1466
1467 (defun widget-default-value-set (widget value)
1468   ;; Recreate widget with new value.
1469   (save-excursion
1470     (goto-char (widget-get widget :from))
1471     (widget-apply widget :delete)
1472     (widget-put widget :value value)
1473     (widget-apply widget :create)))
1474
1475 (defun widget-default-value-inline (widget)
1476   ;; Wrap value in a list unless it is inline.
1477   (if (widget-get widget :inline)
1478       (widget-value widget)
1479     (list (widget-value widget))))
1480
1481 (defun widget-default-menu-tag-get (widget)
1482   ;; Use tag or value for menus.
1483   (or (widget-get widget :menu-tag)
1484       (widget-get widget :tag)
1485       (widget-princ-to-string (widget-get widget :value))))
1486
1487 (defun widget-default-active (widget)
1488   "Return t iff this widget active (user modifiable)."
1489   (and (not (widget-get widget :inactive))
1490        (let ((parent (widget-get widget :parent)))
1491          (or (null parent)
1492              (widget-apply parent :active)))))
1493
1494 (defun widget-default-deactivate (widget)
1495   "Make WIDGET inactive for user modifications."
1496   (widget-specify-inactive widget
1497                            (widget-get widget :from)
1498                            (widget-get widget :to)))
1499
1500 (defun widget-default-action (widget &optional event)
1501   ;; Notify the parent when a widget change
1502   (let ((parent (widget-get widget :parent)))
1503     (when parent
1504       (widget-apply parent :notify widget event))))
1505
1506 (defun widget-default-notify (widget child &optional event)
1507   ;; Pass notification to parent.
1508   (widget-default-action widget event))
1509
1510 (defun widget-default-prompt-value (widget prompt value unbound)
1511   ;; Read an arbitrary value.  Stolen from `set-variable'.
1512 ;;  (let ((initial (if unbound
1513 ;;                   nil
1514 ;;                 ;; It would be nice if we could do a `(cons val 1)' here.
1515 ;;                 (prin1-to-string (custom-quote value))))))
1516   (eval-minibuffer prompt ))
1517
1518 ;;; The `item' Widget.
1519
1520 (define-widget 'item 'default
1521   "Constant items for inclusion in other widgets."
1522   :convert-widget 'widget-value-convert-widget
1523   :value-create 'widget-item-value-create
1524   :value-delete 'ignore
1525   :value-get 'widget-value-value-get
1526   :match 'widget-item-match
1527   :match-inline 'widget-item-match-inline
1528   :action 'widget-item-action
1529   :format "%t\n")
1530
1531 (defun widget-item-value-create (widget)
1532   ;; Insert the printed representation of the value.
1533   (let ((standard-output (current-buffer)))
1534     (princ (widget-get widget :value))))
1535
1536 (defun widget-item-match (widget value)
1537   ;; Match if the value is the same.
1538   (equal (widget-get widget :value) value))
1539
1540 (defun widget-item-match-inline (widget values)
1541   ;; Match if the value is the same.
1542   (let ((value (widget-get widget :value)))
1543     (and (listp value)
1544          (<= (length value) (length values))
1545          (let ((head (widget-sublist values 0 (length value))))
1546            (and (equal head value)
1547                 (cons head (widget-sublist values (length value))))))))
1548
1549 (defun widget-sublist (list start &optional end)
1550   "Return the sublist of LIST from START to END.
1551 If END is omitted, it defaults to the length of LIST."
1552   (if (> start 0) (setq list (nthcdr start list)))
1553   (if end
1554       (if (<= end start)
1555           nil
1556         (setq list (copy-sequence list))
1557         (setcdr (nthcdr (- end start 1) list) nil)
1558         list)
1559     (copy-sequence list)))
1560
1561 (defun widget-item-action (widget &optional event)
1562   ;; Just notify itself.
1563   (widget-apply widget :notify widget event))
1564
1565 ;;; The `push-button' Widget.
1566
1567 (defcustom widget-push-button-gui t
1568   "If non nil, use GUI push buttons when available."
1569   :group 'widgets
1570   :type 'boolean)
1571
1572 ;; Cache already created GUI objects.
1573 (defvar widget-push-button-cache nil)
1574
1575 (defcustom widget-push-button-prefix "["
1576   "String used as prefix for buttons."
1577   :type 'string
1578   :group 'widget-button)
1579
1580 (defcustom widget-push-button-suffix "]"
1581   "String used as suffix for buttons."
1582   :type 'string
1583   :group 'widget-button)
1584
1585 (define-widget 'push-button 'item
1586   "A pushable button."
1587   :button-prefix ""
1588   :button-suffix ""
1589   :value-create 'widget-push-button-value-create
1590   :format "%[%v%]")
1591
1592 (defun widget-push-button-value-create (widget)
1593   ;; Insert text representing the `on' and `off' states.
1594   (let* ((tag (or (widget-get widget :tag)
1595                   (widget-get widget :value)))
1596          (text (concat widget-push-button-prefix
1597                        tag widget-push-button-suffix))
1598          (gui (cdr (assoc tag widget-push-button-cache))))
1599     (if (and (fboundp 'make-gui-button)
1600              (fboundp 'make-glyph)
1601              widget-push-button-gui
1602              (fboundp 'device-on-window-system-p)
1603              (device-on-window-system-p)
1604              (string-match "XEmacs" emacs-version))
1605         (progn
1606           (unless gui
1607             (setq gui (make-gui-button tag 'widget-gui-action widget))
1608             (push (cons tag gui) widget-push-button-cache))
1609           (widget-glyph-insert-glyph widget
1610                                      (make-glyph
1611                                       (list (nth 0 (aref gui 1))
1612                                             (vector 'string ':data text)))
1613                                      (make-glyph
1614                                       (list (nth 1 (aref gui 1))
1615                                             (vector 'string ':data text)))
1616                                      (make-glyph
1617                                       (list (nth 2 (aref gui 1))
1618                                             (vector 'string ':data text)))))
1619       (insert text))))
1620
1621 (defun widget-gui-action (widget)
1622   "Apply :action for WIDGET."
1623   (widget-apply-action widget (this-command-keys)))
1624
1625 ;;; The `link' Widget.
1626
1627 (defcustom widget-link-prefix "["
1628   "String used as prefix for links."
1629   :type 'string
1630   :group 'widget-button)
1631
1632 (defcustom widget-link-suffix "]"
1633   "String used as suffix for links."
1634   :type 'string
1635   :group 'widget-button)
1636
1637 (define-widget 'link 'item
1638   "An embedded link."
1639   :button-prefix 'widget-link-prefix
1640   :button-suffix 'widget-link-suffix
1641   :help-echo "Follow the link."
1642   :format "%[%t%]")
1643
1644 ;;; The `info-link' Widget.
1645
1646 (define-widget 'info-link 'link
1647   "A link to an info file."
1648   :action 'widget-info-link-action)
1649
1650 (defun widget-info-link-action (widget &optional event)
1651   "Open the info node specified by WIDGET."
1652   (Info-goto-node (widget-value widget)))
1653
1654 ;;; The `url-link' Widget.
1655
1656 (define-widget 'url-link 'link
1657   "A link to an www page."
1658   :action 'widget-url-link-action)
1659
1660 (defun widget-url-link-action (widget &optional event)
1661   "Open the url specified by WIDGET."
1662   (require 'browse-url)
1663   (funcall browse-url-browser-function (widget-value widget)))
1664
1665 ;;; The `editable-field' Widget.
1666
1667 (define-widget 'editable-field 'default
1668   "An editable text field."
1669   :convert-widget 'widget-value-convert-widget
1670   :keymap widget-field-keymap
1671   :format "%v"
1672   :value ""
1673   :prompt-internal 'widget-field-prompt-internal
1674   :prompt-history 'widget-field-history
1675   :prompt-value 'widget-field-prompt-value
1676   :action 'widget-field-action
1677   :validate 'widget-field-validate
1678   :valid-regexp ""
1679   :error "No match"
1680   :value-create 'widget-field-value-create
1681   :value-delete 'widget-field-value-delete
1682   :value-get 'widget-field-value-get
1683   :match 'widget-field-match)
1684
1685 (defvar widget-field-history nil
1686   "History of field minibuffer edits.")
1687
1688 (defun widget-field-prompt-internal (widget prompt initial history)
1689   ;; Read string for WIDGET promptinhg with PROMPT.
1690   ;; INITIAL is the initial input and HISTORY is a symbol containing
1691   ;; the earlier input.
1692   (read-string prompt initial history))
1693
1694 (defun widget-field-prompt-value (widget prompt value unbound)
1695   ;; Prompt for a string.
1696   (let ((initial (if unbound
1697                      nil
1698                    (cons (widget-apply widget :value-to-internal
1699                                        value) 0)))
1700         (history (widget-get widget :prompt-history)))
1701     (let ((answer (widget-apply widget
1702                                 :prompt-internal prompt initial history)))
1703       (widget-apply widget :value-to-external answer))))
1704
1705 (defun widget-field-action (widget &optional event)
1706   ;; Edit the value in the minibuffer.
1707   (let ((invalid (widget-apply widget :validate)))
1708     (let ((prompt (concat (widget-apply widget :menu-tag-get) ": "))
1709           (value (unless invalid
1710                    (widget-value widget))))
1711       (let ((answer (widget-apply widget :prompt-value prompt value invalid) ))
1712         (widget-value-set widget answer)))
1713     (widget-setup)
1714     (widget-apply widget :notify widget event)))
1715
1716 (defun widget-field-validate (widget)
1717   ;; Valid if the content matches `:valid-regexp'.
1718   (save-excursion
1719     (let ((value (widget-apply widget :value-get))
1720           (regexp (widget-get widget :valid-regexp)))
1721       (if (string-match regexp value)
1722           nil
1723         widget))))
1724
1725 (defun widget-field-value-create (widget)
1726   ;; Create an editable text field.
1727   (let ((size (widget-get widget :size))
1728         (value (widget-get widget :value))
1729         (from (point))
1730         (overlay (cons (make-marker) (make-marker))))
1731     (widget-put widget :field-overlay overlay)
1732     (insert value)
1733     (and size
1734          (< (length value) size)
1735          (insert-char ?\  (- size (length value))))
1736     (unless (memq widget widget-field-list)
1737       (setq widget-field-new (cons widget widget-field-new)))
1738     (move-marker (cdr overlay) (point))
1739     (set-marker-insertion-type (cdr overlay) nil)
1740     (when (null size)
1741       (insert ?\n))
1742     (move-marker (car overlay) from)
1743     (set-marker-insertion-type (car overlay) t)))
1744
1745 (defun widget-field-value-delete (widget)
1746   ;; Remove the widget from the list of active editing fields.
1747   (setq widget-field-list (delq widget widget-field-list))
1748   ;; These are nil if the :format string doesn't contain `%v'.
1749   (let ((overlay (widget-get widget :field-overlay)))
1750     (when overlay
1751       (delete-overlay overlay))))
1752
1753 (defun widget-field-value-get (widget)
1754   ;; Return current text in editing field.
1755   (let ((from (widget-field-start widget))
1756         (to (widget-field-end widget))
1757         (buffer (widget-field-buffer widget))
1758         (size (widget-get widget :size))
1759         (secret (widget-get widget :secret))
1760         (old (current-buffer)))
1761     (if (and from to)
1762         (progn
1763           (set-buffer buffer)
1764           (while (and size
1765                       (not (zerop size))
1766                       (> to from)
1767                       (eq (char-after (1- to)) ?\ ))
1768             (setq to (1- to)))
1769           (let ((result (buffer-substring-no-properties from to)))
1770             (when secret
1771               (let ((index 0))
1772                 (while (< (+ from index) to)
1773                   (aset result index
1774                         (get-char-property (+ from index) 'secret))
1775                   (setq index (1+ index)))))
1776             (set-buffer old)
1777             result))
1778       (widget-get widget :value))))
1779
1780 (defun widget-field-match (widget value)
1781   ;; Match any string.
1782   (stringp value))
1783
1784 ;;; The `text' Widget.
1785
1786 (define-widget 'text 'editable-field
1787   :keymap widget-text-keymap
1788   "A multiline text area.")
1789
1790 ;;; The `menu-choice' Widget.
1791
1792 (define-widget 'menu-choice 'default
1793   "A menu of options."
1794   :convert-widget  'widget-types-convert-widget
1795   :format "%[%t%]: %v"
1796   :case-fold t
1797   :tag "choice"
1798   :void '(item :format "invalid (%t)\n")
1799   :value-create 'widget-choice-value-create
1800   :value-delete 'widget-children-value-delete
1801   :value-get 'widget-choice-value-get
1802   :value-inline 'widget-choice-value-inline
1803   :mouse-down-action 'widget-choice-mouse-down-action
1804   :action 'widget-choice-action
1805   :error "Make a choice"
1806   :validate 'widget-choice-validate
1807   :match 'widget-choice-match
1808   :match-inline 'widget-choice-match-inline)
1809
1810 (defun widget-choice-value-create (widget)
1811   ;; Insert the first choice that matches the value.
1812   (let ((value (widget-get widget :value))
1813         (args (widget-get widget :args))
1814         current)
1815     (while args
1816       (setq current (car args)
1817             args (cdr args))
1818       (when (widget-apply current :match value)
1819         (widget-put widget :children (list (widget-create-child-value
1820                                             widget current value)))
1821         (widget-put widget :choice current)
1822         (setq args nil
1823               current nil)))
1824     (when current
1825       (let ((void (widget-get widget :void)))
1826         (widget-put widget :children (list (widget-create-child-and-convert
1827                                             widget void :value value)))
1828         (widget-put widget :choice void)))))
1829
1830 (defun widget-choice-value-get (widget)
1831   ;; Get value of the child widget.
1832   (widget-value (car (widget-get widget :children))))
1833
1834 (defun widget-choice-value-inline (widget)
1835   ;; Get value of the child widget.
1836   (widget-apply (car (widget-get widget :children)) :value-inline))
1837
1838 (defcustom widget-choice-toggle nil
1839   "If non-nil, a binary choice will just toggle between the values.
1840 Otherwise, the user will explicitly have to choose between the values
1841 when he invoked the menu."
1842   :type 'boolean
1843   :group 'widgets)
1844
1845 (defun widget-choice-mouse-down-action (widget &optional event)
1846   ;; Return non-nil if we need a menu.
1847   (let ((args (widget-get widget :args))
1848         (old (widget-get widget :choice)))
1849     (cond ((not window-system)
1850            ;; No place to pop up a menu.
1851            nil)
1852           ((not (or (fboundp 'x-popup-menu) (fboundp 'popup-menu)))
1853            ;; No way to pop up a menu.
1854            nil)
1855           ((< (length args) 2)
1856            ;; Empty or singleton list, just return the value.
1857            nil)
1858           ((> (length args) widget-menu-max-size)
1859            ;; Too long, prompt.
1860            nil)
1861           ((> (length args) 2)
1862            ;; Reasonable sized list, use menu.
1863            t)
1864           ((and widget-choice-toggle (memq old args))
1865            ;; We toggle.
1866            nil)
1867           (t
1868            ;; Ask which of the two.
1869            t))))
1870
1871 (defun widget-choice-action (widget &optional event)
1872   ;; Make a choice.
1873   (let ((args (widget-get widget :args))
1874         (old (widget-get widget :choice))
1875         (tag (widget-apply widget :menu-tag-get))
1876         (completion-ignore-case (widget-get widget :case-fold))
1877         current choices)
1878     ;; Remember old value.
1879     (if (and old (not (widget-apply widget :validate)))
1880         (let* ((external (widget-value widget))
1881                (internal (widget-apply old :value-to-internal external)))
1882           (widget-put old :value internal)))
1883     ;; Find new choice.
1884     (setq current
1885           (cond ((= (length args) 0)
1886                  nil)
1887                 ((= (length args) 1)
1888                  (nth 0 args))
1889                 ((and widget-choice-toggle
1890                       (= (length args) 2)
1891                       (memq old args))
1892                  (if (eq old (nth 0 args))
1893                      (nth 1 args)
1894                    (nth 0 args)))
1895                 (t
1896                  (while args
1897                    (setq current (car args)
1898                          args (cdr args))
1899                    (setq choices
1900                          (cons (cons (widget-apply current :menu-tag-get)
1901                                      current)
1902                                choices)))
1903                  (widget-choose tag (reverse choices) event))))
1904     (when current
1905       (widget-value-set widget
1906                         (widget-apply current :value-to-external
1907                                       (widget-get current :value)))
1908       (widget-setup)
1909       (widget-apply widget :notify widget event))))
1910
1911 (defun widget-choice-validate (widget)
1912   ;; Valid if we have made a valid choice.
1913   (let ((void (widget-get widget :void))
1914         (choice (widget-get widget :choice))
1915         (child (car (widget-get widget :children))))
1916     (if (eq void choice)
1917         widget
1918       (widget-apply child :validate))))
1919
1920 (defun widget-choice-match (widget value)
1921   ;; Matches if one of the choices matches.
1922   (let ((args (widget-get widget :args))
1923         current found)
1924     (while (and args (not found))
1925       (setq current (car args)
1926             args (cdr args)
1927             found (widget-apply current :match value)))
1928     found))
1929
1930 (defun widget-choice-match-inline (widget values)
1931   ;; Matches if one of the choices matches.
1932   (let ((args (widget-get widget :args))
1933         current found)
1934     (while (and args (null found))
1935       (setq current (car args)
1936             args (cdr args)
1937             found (widget-match-inline current values)))
1938     found))
1939
1940 ;;; The `toggle' Widget.
1941
1942 (define-widget 'toggle 'item
1943   "Toggle between two states."
1944   :format "%[%v%]\n"
1945   :value-create 'widget-toggle-value-create
1946   :action 'widget-toggle-action
1947   :match (lambda (widget value) t)
1948   :on "on"
1949   :off "off")
1950
1951 (defun widget-toggle-value-create (widget)
1952   ;; Insert text representing the `on' and `off' states.
1953   (if (widget-value widget)
1954       (widget-glyph-insert widget
1955                            (widget-get widget :on)
1956                            (widget-get widget :on-glyph))
1957     (widget-glyph-insert widget
1958                          (widget-get widget :off)
1959                          (widget-get widget :off-glyph))))
1960
1961 (defun widget-toggle-action (widget &optional event)
1962   ;; Toggle value.
1963   (widget-value-set widget (not (widget-value widget)))
1964   (widget-apply widget :notify widget event))
1965
1966 ;;; The `checkbox' Widget.
1967
1968 (define-widget 'checkbox 'toggle
1969   "A checkbox toggle."
1970   :button-suffix ""
1971   :button-prefix ""
1972   :format "%[%v%]"
1973   :on "[X]"
1974   :on-glyph "check1"
1975   :off "[ ]"
1976   :off-glyph "check0"
1977   :action 'widget-checkbox-action)
1978
1979 (defun widget-checkbox-action (widget &optional event)
1980   "Toggle checkbox, notify parent, and set active state of sibling."
1981   (widget-toggle-action widget event)
1982   (let ((sibling (widget-get-sibling widget)))
1983     (when sibling
1984       (if (widget-value widget)
1985           (widget-apply sibling :activate)
1986         (widget-apply sibling :deactivate)))))
1987
1988 ;;; The `checklist' Widget.
1989
1990 (define-widget 'checklist 'default
1991   "A multiple choice widget."
1992   :convert-widget 'widget-types-convert-widget
1993   :format "%v"
1994   :offset 4
1995   :entry-format "%b %v"
1996   :menu-tag "checklist"
1997   :greedy nil
1998   :value-create 'widget-checklist-value-create
1999   :value-delete 'widget-children-value-delete
2000   :value-get 'widget-checklist-value-get
2001   :validate 'widget-checklist-validate
2002   :match 'widget-checklist-match
2003   :match-inline 'widget-checklist-match-inline)
2004
2005 (defun widget-checklist-value-create (widget)
2006   ;; Insert all values
2007   (let ((alist (widget-checklist-match-find widget (widget-get widget :value)))
2008         (args (widget-get widget :args)))
2009     (while args
2010       (widget-checklist-add-item widget (car args) (assq (car args) alist))
2011       (setq args (cdr args)))
2012     (widget-put widget :children (nreverse (widget-get widget :children)))))
2013
2014 (defun widget-checklist-add-item (widget type chosen)
2015   ;; Create checklist item in WIDGET of type TYPE.
2016   ;; If the item is checked, CHOSEN is a cons whose cdr is the value.
2017   (and (eq (preceding-char) ?\n)
2018        (widget-get widget :indent)
2019        (insert-char ?  (widget-get widget :indent)))
2020   (widget-specify-insert
2021    (let* ((children (widget-get widget :children))
2022           (buttons (widget-get widget :buttons))
2023           (button-args (or (widget-get type :sibling-args)
2024                            (widget-get widget :button-args)))
2025           (from (point))
2026           child button)
2027      (insert (widget-get widget :entry-format))
2028      (goto-char from)
2029      ;; Parse % escapes in format.
2030      (while (re-search-forward "%\\([bv%]\\)" nil t)
2031        (let ((escape (aref (match-string 1) 0)))
2032          (replace-match "" t t)
2033          (cond ((eq escape ?%)
2034                 (insert "%"))
2035                ((eq escape ?b)
2036                 (setq button (apply 'widget-create-child-and-convert
2037                                     widget 'checkbox
2038                                     :value (not (null chosen))
2039                                     button-args)))
2040                ((eq escape ?v)
2041                 (setq child
2042                       (cond ((not chosen)
2043                              (let ((child (widget-create-child widget type)))
2044                                (widget-apply child :deactivate)
2045                                child))
2046                             ((widget-get type :inline)
2047                              (widget-create-child-value
2048                               widget type (cdr chosen)))
2049                             (t
2050                              (widget-create-child-value
2051                               widget type (car (cdr chosen)))))))
2052                (t
2053                 (error "Unknown escape `%c'" escape)))))
2054      ;; Update properties.
2055      (and button child (widget-put child :button button))
2056      (and button (widget-put widget :buttons (cons button buttons)))
2057      (and child (widget-put widget :children (cons child children))))))
2058
2059 (defun widget-checklist-match (widget values)
2060   ;; All values must match a type in the checklist.
2061   (and (listp values)
2062        (null (cdr (widget-checklist-match-inline widget values)))))
2063
2064 (defun widget-checklist-match-inline (widget values)
2065   ;; Find the values which match a type in the checklist.
2066   (let ((greedy (widget-get widget :greedy))
2067         (args (copy-sequence (widget-get widget :args)))
2068         found rest)
2069     (while values
2070       (let ((answer (widget-checklist-match-up args values)))
2071         (cond (answer
2072                (let ((vals (widget-match-inline answer values)))
2073                  (setq found (append found (car vals))
2074                        values (cdr vals)
2075                        args (delq answer args))))
2076               (greedy
2077                (setq rest (append rest (list (car values)))
2078                      values (cdr values)))
2079               (t
2080                (setq rest (append rest values)
2081                      values nil)))))
2082     (cons found rest)))
2083
2084 (defun widget-checklist-match-find (widget vals)
2085   ;; Find the vals which match a type in the checklist.
2086   ;; Return an alist of (TYPE MATCH).
2087   (let ((greedy (widget-get widget :greedy))
2088         (args (copy-sequence (widget-get widget :args)))
2089         found)
2090     (while vals
2091       (let ((answer (widget-checklist-match-up args vals)))
2092         (cond (answer
2093                (let ((match (widget-match-inline answer vals)))
2094                  (setq found (cons (cons answer (car match)) found)
2095                        vals (cdr match)
2096                        args (delq answer args))))
2097               (greedy
2098                (setq vals (cdr vals)))
2099               (t
2100                (setq vals nil)))))
2101     found))
2102
2103 (defun widget-checklist-match-up (args vals)
2104   ;; Rerturn the first type from ARGS that matches VALS.
2105   (let (current found)
2106     (while (and args (null found))
2107       (setq current (car args)
2108             args (cdr args)
2109             found (widget-match-inline current vals)))
2110     (if found
2111         current
2112       nil)))
2113
2114 (defun widget-checklist-value-get (widget)
2115   ;; The values of all selected items.
2116   (let ((children (widget-get widget :children))
2117         child result)
2118     (while children
2119       (setq child (car children)
2120             children (cdr children))
2121       (if (widget-value (widget-get child :button))
2122           (setq result (append result (widget-apply child :value-inline)))))
2123     result))
2124
2125 (defun widget-checklist-validate (widget)
2126   ;; Ticked chilren must be valid.
2127   (let ((children (widget-get widget :children))
2128         child button found)
2129     (while (and children (not found))
2130       (setq child (car children)
2131             children (cdr children)
2132             button (widget-get child :button)
2133             found (and (widget-value button)
2134                        (widget-apply child :validate))))
2135     found))
2136
2137 ;;; The `option' Widget
2138
2139 (define-widget 'option 'checklist
2140   "An widget with an optional item."
2141   :inline t)
2142
2143 ;;; The `choice-item' Widget.
2144
2145 (define-widget 'choice-item 'item
2146   "Button items that delegate action events to their parents."
2147   :action 'widget-parent-action
2148   :format "%[%t%] \n")
2149
2150 ;;; The `radio-button' Widget.
2151
2152 (define-widget 'radio-button 'toggle
2153   "A radio button for use in the `radio' widget."
2154   :notify 'widget-radio-button-notify
2155   :format "%[%v%]"
2156   :button-suffix ""
2157   :button-prefix ""
2158   :on "(*)"
2159   :on-glyph "radio1"
2160   :off "( )"
2161   :off-glyph "radio0")
2162
2163 (defun widget-radio-button-notify (widget child &optional event)
2164   ;; Tell daddy.
2165   (widget-apply (widget-get widget :parent) :action widget event))
2166
2167 ;;; The `radio-button-choice' Widget.
2168
2169 (define-widget 'radio-button-choice 'default
2170   "Select one of multiple options."
2171   :convert-widget 'widget-types-convert-widget
2172   :offset 4
2173   :format "%v"
2174   :entry-format "%b %v"
2175   :menu-tag "radio"
2176   :value-create 'widget-radio-value-create
2177   :value-delete 'widget-children-value-delete
2178   :value-get 'widget-radio-value-get
2179   :value-inline 'widget-radio-value-inline
2180   :value-set 'widget-radio-value-set
2181   :error "You must push one of the buttons"
2182   :validate 'widget-radio-validate
2183   :match 'widget-choice-match
2184   :match-inline 'widget-choice-match-inline
2185   :action 'widget-radio-action)
2186
2187 (defun widget-radio-value-create (widget)
2188   ;; Insert all values
2189   (let ((args (widget-get widget :args))
2190         arg)
2191     (while args
2192       (setq arg (car args)
2193             args (cdr args))
2194       (widget-radio-add-item widget arg))))
2195
2196 (defun widget-radio-add-item (widget type)
2197   "Add to radio widget WIDGET a new radio button item of type TYPE."
2198   ;; (setq type (widget-convert type))
2199   (and (eq (preceding-char) ?\n)
2200        (widget-get widget :indent)
2201        (insert-char ?  (widget-get widget :indent)))
2202   (widget-specify-insert
2203    (let* ((value (widget-get widget :value))
2204           (children (widget-get widget :children))
2205           (buttons (widget-get widget :buttons))
2206           (button-args (or (widget-get type :sibling-args)
2207                            (widget-get widget :button-args)))
2208           (from (point))
2209           (chosen (and (null (widget-get widget :choice))
2210                        (widget-apply type :match value)))
2211           child button)
2212      (insert (widget-get widget :entry-format))
2213      (goto-char from)
2214      ;; Parse % escapes in format.
2215      (while (re-search-forward "%\\([bv%]\\)" nil t)
2216        (let ((escape (aref (match-string 1) 0)))
2217          (replace-match "" t t)
2218          (cond ((eq escape ?%)
2219                 (insert "%"))
2220                ((eq escape ?b)
2221                 (setq button (apply 'widget-create-child-and-convert
2222                                     widget 'radio-button
2223                                     :value (not (null chosen))
2224                                     button-args)))
2225                ((eq escape ?v)
2226                 (setq child (if chosen
2227                                 (widget-create-child-value
2228                                  widget type value)
2229                               (widget-create-child widget type)))
2230                 (unless chosen
2231                   (widget-apply child :deactivate)))
2232                (t
2233                 (error "Unknown escape `%c'" escape)))))
2234      ;; Update properties.
2235      (when chosen
2236        (widget-put widget :choice type))
2237      (when button
2238        (widget-put child :button button)
2239        (widget-put widget :buttons (nconc buttons (list button))))
2240      (when child
2241        (widget-put widget :children (nconc children (list child))))
2242      child)))
2243
2244 (defun widget-radio-value-get (widget)
2245   ;; Get value of the child widget.
2246   (let ((chosen (widget-radio-chosen widget)))
2247     (and chosen (widget-value chosen))))
2248
2249 (defun widget-radio-chosen (widget)
2250   "Return the widget representing the chosen radio button."
2251   (let ((children (widget-get widget :children))
2252         current found)
2253     (while children
2254       (setq current (car children)
2255             children (cdr children))
2256       (let* ((button (widget-get current :button))
2257              (value (widget-apply button :value-get)))
2258         (when value
2259           (setq found current
2260                 children nil))))
2261     found))
2262
2263 (defun widget-radio-value-inline (widget)
2264   ;; Get value of the child widget.
2265   (let ((children (widget-get widget :children))
2266         current found)
2267     (while children
2268       (setq current (car children)
2269             children (cdr children))
2270       (let* ((button (widget-get current :button))
2271              (value (widget-apply button :value-get)))
2272         (when value
2273           (setq found (widget-apply current :value-inline)
2274                 children nil))))
2275     found))
2276
2277 (defun widget-radio-value-set (widget value)
2278   ;; We can't just delete and recreate a radio widget, since children
2279   ;; can be added after the original creation and won't be recreated
2280   ;; by `:create'.
2281   (let ((children (widget-get widget :children))
2282         current found)
2283     (while children
2284       (setq current (car children)
2285             children (cdr children))
2286       (let* ((button (widget-get current :button))
2287              (match (and (not found)
2288                          (widget-apply current :match value))))
2289         (widget-value-set button match)
2290         (if match
2291             (progn
2292               (widget-value-set current value)
2293               (widget-apply current :activate))
2294           (widget-apply current :deactivate))
2295         (setq found (or found match))))))
2296
2297 (defun widget-radio-validate (widget)
2298   ;; Valid if we have made a valid choice.
2299   (let ((children (widget-get widget :children))
2300         current found button)
2301     (while (and children (not found))
2302       (setq current (car children)
2303             children (cdr children)
2304             button (widget-get current :button)
2305             found (widget-apply button :value-get)))
2306     (if found
2307         (widget-apply current :validate)
2308       widget)))
2309
2310 (defun widget-radio-action (widget child event)
2311   ;; Check if a radio button was pressed.
2312   (let ((children (widget-get widget :children))
2313         (buttons (widget-get widget :buttons))
2314         current)
2315     (when (memq child buttons)
2316       (while children
2317         (setq current (car children)
2318               children (cdr children))
2319         (let* ((button (widget-get current :button)))
2320           (cond ((eq child button)
2321                  (widget-value-set button t)
2322                  (widget-apply current :activate))
2323                 ((widget-value button)
2324                  (widget-value-set button nil)
2325                  (widget-apply current :deactivate)))))))
2326   ;; Pass notification to parent.
2327   (widget-apply widget :notify child event))
2328
2329 ;;; The `insert-button' Widget.
2330
2331 (define-widget 'insert-button 'push-button
2332   "An insert button for the `editable-list' widget."
2333   :tag "INS"
2334   :help-echo "Insert a new item into the list at this position."
2335   :action 'widget-insert-button-action)
2336
2337 (defun widget-insert-button-action (widget &optional event)
2338   ;; Ask the parent to insert a new item.
2339   (widget-apply (widget-get widget :parent)
2340                 :insert-before (widget-get widget :widget)))
2341
2342 ;;; The `delete-button' Widget.
2343
2344 (define-widget 'delete-button 'push-button
2345   "A delete button for the `editable-list' widget."
2346   :tag "DEL"
2347   :help-echo "Delete this item from the list."
2348   :action 'widget-delete-button-action)
2349
2350 (defun widget-delete-button-action (widget &optional event)
2351   ;; Ask the parent to insert a new item.
2352   (widget-apply (widget-get widget :parent)
2353                 :delete-at (widget-get widget :widget)))
2354
2355 ;;; The `editable-list' Widget.
2356
2357 (defcustom widget-editable-list-gui nil
2358   "If non nil, use GUI push-buttons in editable list when available."
2359   :type 'boolean
2360   :group 'widgets)
2361
2362 (define-widget 'editable-list 'default
2363   "A variable list of widgets of the same type."
2364   :convert-widget 'widget-types-convert-widget
2365   :offset 12
2366   :format "%v%i\n"
2367   :format-handler 'widget-editable-list-format-handler
2368   :entry-format "%i %d %v"
2369   :menu-tag "editable-list"
2370   :value-create 'widget-editable-list-value-create
2371   :value-delete 'widget-children-value-delete
2372   :value-get 'widget-editable-list-value-get
2373   :validate 'widget-children-validate
2374   :match 'widget-editable-list-match
2375   :match-inline 'widget-editable-list-match-inline
2376   :insert-before 'widget-editable-list-insert-before
2377   :delete-at 'widget-editable-list-delete-at)
2378
2379 (defun widget-editable-list-format-handler (widget escape)
2380   ;; We recognize the insert button.
2381   (let ((widget-push-button-gui widget-editable-list-gui))
2382     (cond ((eq escape ?i)
2383            (and (widget-get widget :indent)
2384                 (insert-char ?  (widget-get widget :indent)))
2385            (apply 'widget-create-child-and-convert
2386                   widget 'insert-button
2387                   (widget-get widget :append-button-args)))
2388           (t
2389            (widget-default-format-handler widget escape)))))
2390
2391 (defun widget-editable-list-value-create (widget)
2392   ;; Insert all values
2393   (let* ((value (widget-get widget :value))
2394          (type (nth 0 (widget-get widget :args)))
2395          (inlinep (widget-get type :inline))
2396          children)
2397     (widget-put widget :value-pos (copy-marker (point)))
2398     (set-marker-insertion-type (widget-get widget :value-pos) t)
2399     (while value
2400       (let ((answer (widget-match-inline type value)))
2401         (if answer
2402             (setq children (cons (widget-editable-list-entry-create
2403                                   widget
2404                                   (if inlinep
2405                                       (car answer)
2406                                     (car (car answer)))
2407                                   t)
2408                                  children)
2409                   value (cdr answer))
2410           (setq value nil))))
2411     (widget-put widget :children (nreverse children))))
2412
2413 (defun widget-editable-list-value-get (widget)
2414   ;; Get value of the child widget.
2415   (apply 'append (mapcar (lambda (child) (widget-apply child :value-inline))
2416                          (widget-get widget :children))))
2417
2418 (defun widget-editable-list-match (widget value)
2419   ;; Value must be a list and all the members must match the type.
2420   (and (listp value)
2421        (null (cdr (widget-editable-list-match-inline widget value)))))
2422
2423 (defun widget-editable-list-match-inline (widget value)
2424   (let ((type (nth 0 (widget-get widget :args)))
2425         (ok t)
2426         found)
2427     (while (and value ok)
2428       (let ((answer (widget-match-inline type value)))
2429         (if answer
2430             (setq found (append found (car answer))
2431                   value (cdr answer))
2432           (setq ok nil))))
2433     (cons found value)))
2434
2435 (defun widget-editable-list-insert-before (widget before)
2436   ;; Insert a new child in the list of children.
2437   (save-excursion
2438     (let ((children (widget-get widget :children))
2439           (inhibit-read-only t)
2440           before-change-functions
2441           after-change-functions)
2442       (cond (before
2443              (goto-char (widget-get before :entry-from)))
2444             (t
2445              (goto-char (widget-get widget :value-pos))))
2446       (let ((child (widget-editable-list-entry-create
2447                     widget nil nil)))
2448         (when (< (widget-get child :entry-from) (widget-get widget :from))
2449           (set-marker (widget-get widget :from)
2450                       (widget-get child :entry-from)))
2451         (widget-specify-text (widget-get child :entry-from)
2452                              (widget-get child :entry-to))
2453         (if (eq (car children) before)
2454             (widget-put widget :children (cons child children))
2455           (while (not (eq (car (cdr children)) before))
2456             (setq children (cdr children)))
2457           (setcdr children (cons child (cdr children)))))))
2458   (widget-setup)
2459   (widget-apply widget :notify widget))
2460
2461 (defun widget-editable-list-delete-at (widget child)
2462   ;; Delete child from list of children.
2463   (save-excursion
2464     (let ((buttons (copy-sequence (widget-get widget :buttons)))
2465           button
2466           (inhibit-read-only t)
2467           before-change-functions
2468           after-change-functions)
2469       (while buttons
2470         (setq button (car buttons)
2471               buttons (cdr buttons))
2472         (when (eq (widget-get button :widget) child)
2473           (widget-put widget
2474                       :buttons (delq button (widget-get widget :buttons)))
2475           (widget-delete button))))
2476     (let ((entry-from (widget-get child :entry-from))
2477           (entry-to (widget-get child :entry-to))
2478           (inhibit-read-only t)
2479           before-change-functions
2480           after-change-functions)
2481       (widget-delete child)
2482       (delete-region entry-from entry-to)
2483       (set-marker entry-from nil)
2484       (set-marker entry-to nil))
2485     (widget-put widget :children (delq child (widget-get widget :children))))
2486   (widget-setup)
2487   (widget-apply widget :notify widget))
2488
2489 (defun widget-editable-list-entry-create (widget value conv)
2490   ;; Create a new entry to the list.
2491   (let ((type (nth 0 (widget-get widget :args)))
2492         (widget-push-button-gui widget-editable-list-gui)
2493         child delete insert)
2494     (widget-specify-insert
2495      (save-excursion
2496        (and (widget-get widget :indent)
2497             (insert-char ?  (widget-get widget :indent)))
2498        (insert (widget-get widget :entry-format)))
2499      ;; Parse % escapes in format.
2500      (while (re-search-forward "%\\(.\\)" nil t)
2501        (let ((escape (aref (match-string 1) 0)))
2502          (replace-match "" t t)
2503          (cond ((eq escape ?%)
2504                 (insert "%"))
2505                ((eq escape ?i)
2506                 (setq insert (apply 'widget-create-child-and-convert
2507                                     widget 'insert-button
2508                                     (widget-get widget :insert-button-args))))
2509                ((eq escape ?d)
2510                 (setq delete (apply 'widget-create-child-and-convert
2511                                     widget 'delete-button
2512                                     (widget-get widget :delete-button-args))))
2513                ((eq escape ?v)
2514                 (if conv
2515                     (setq child (widget-create-child-value
2516                                  widget type value))
2517                   (setq child (widget-create-child widget type))))
2518                (t
2519                 (error "Unknown escape `%c'" escape)))))
2520      (widget-put widget
2521                  :buttons (cons delete
2522                                 (cons insert
2523                                       (widget-get widget :buttons))))
2524      (let ((entry-from (copy-marker (point-min)))
2525            (entry-to (copy-marker (point-max))))
2526        (widget-specify-text entry-from entry-to)
2527        (set-marker-insertion-type entry-from t)
2528        (set-marker-insertion-type entry-to nil)
2529        (widget-put child :entry-from entry-from)
2530        (widget-put child :entry-to entry-to)))
2531     (widget-put insert :widget child)
2532     (widget-put delete :widget child)
2533     child))
2534
2535 ;;; The `group' Widget.
2536
2537 (define-widget 'group 'default
2538   "A widget which group other widgets inside."
2539   :convert-widget 'widget-types-convert-widget
2540   :format "%v"
2541   :value-create 'widget-group-value-create
2542   :value-delete 'widget-children-value-delete
2543   :value-get 'widget-editable-list-value-get
2544   :validate 'widget-children-validate
2545   :match 'widget-group-match
2546   :match-inline 'widget-group-match-inline)
2547
2548 (defun widget-group-value-create (widget)
2549   ;; Create each component.
2550   (let ((args (widget-get widget :args))
2551         (value (widget-get widget :value))
2552         arg answer children)
2553     (while args
2554       (setq arg (car args)
2555             args (cdr args)
2556             answer (widget-match-inline arg value)
2557             value (cdr answer))
2558       (and (eq (preceding-char) ?\n)
2559            (widget-get widget :indent)
2560            (insert-char ?  (widget-get widget :indent)))
2561       (push (cond ((null answer)
2562                    (widget-create-child widget arg))
2563                   ((widget-get arg :inline)
2564                    (widget-create-child-value widget arg  (car answer)))
2565                   (t
2566                    (widget-create-child-value widget arg  (car (car answer)))))
2567             children))
2568     (widget-put widget :children (nreverse children))))
2569
2570 (defun widget-group-match (widget values)
2571   ;; Match if the components match.
2572   (and (listp values)
2573        (let ((match (widget-group-match-inline widget values)))
2574          (and match (null (cdr match))))))
2575
2576 (defun widget-group-match-inline (widget vals)
2577   ;; Match if the components match.
2578   (let ((args (widget-get widget :args))
2579         argument answer found)
2580     (while args
2581       (setq argument (car args)
2582             args (cdr args)
2583             answer (widget-match-inline argument vals))
2584       (if answer
2585           (setq vals (cdr answer)
2586                 found (append found (car answer)))
2587         (setq vals nil
2588               args nil)))
2589     (if answer
2590         (cons found vals)
2591       nil)))
2592
2593 ;;; The `visibility' Widget.
2594
2595 (define-widget 'visibility 'item
2596   "An indicator and manipulator for hidden items."
2597   :format "%[%v%]"
2598   :button-prefix ""
2599   :button-suffix ""
2600   :on "Hide"
2601   :off "Show"
2602   :value-create 'widget-visibility-value-create
2603   :action 'widget-toggle-action
2604   :match (lambda (widget value) t))
2605
2606 (defun widget-visibility-value-create (widget)
2607   ;; Insert text representing the `on' and `off' states.
2608   (let ((on (widget-get widget :on))
2609         (off (widget-get widget :off)))
2610     (if on
2611         (setq on (concat widget-push-button-prefix
2612                          on
2613                          widget-push-button-suffix))
2614       (setq on ""))
2615     (if off
2616         (setq off (concat widget-push-button-prefix
2617                           off
2618                           widget-push-button-suffix))
2619       (setq off ""))
2620     (if (widget-value widget)
2621         (widget-glyph-insert widget on "down" "down-pushed")
2622       (widget-glyph-insert widget off "right" "right-pushed"))))
2623
2624 ;;; The `documentation-link' Widget.
2625 ;;
2626 ;; This is a helper widget for `documentation-string'.
2627
2628 (define-widget 'documentation-link 'link
2629   "Link type used in documentation strings."
2630   :tab-order -1
2631   :help-echo 'widget-documentation-link-echo-help
2632   :action 'widget-documentation-link-action)
2633
2634 (defun widget-documentation-link-echo-help (widget)
2635   "Tell what this link will describe."
2636   (concat "Describe the `" (widget-get widget :value) "' symbol."))
2637
2638 (defun widget-documentation-link-action (widget &optional event)
2639   "Run apropos on WIDGET's value.  Ignore optional argument EVENT."
2640   (apropos (concat "\\`" (regexp-quote (widget-get widget :value)) "\\'")))
2641
2642 (defcustom widget-documentation-links t
2643   "Add hyperlinks to documentation strings when non-nil."
2644   :type 'boolean
2645   :group 'widget-documentation)
2646
2647 (defcustom widget-documentation-link-regexp "`\\([^\n`' ]+\\)'"
2648   "Regexp for matching potential links in documentation strings.
2649 The first group should be the link itself."
2650   :type 'regexp
2651   :group 'widget-documentation)
2652
2653 (defcustom widget-documentation-link-p 'intern-soft
2654   "Predicate used to test if a string is useful as a link.
2655 The value should be a function.  The function will be called one
2656 argument, a string, and should return non-nil if there should be a
2657 link for that string."
2658   :type 'function
2659   :options '(widget-documentation-link-p)
2660   :group 'widget-documentation)
2661
2662 (defcustom widget-documentation-link-type 'documentation-link
2663   "Widget type used for links in documentation strings."
2664   :type 'symbol
2665   :group 'widget-documentation)
2666
2667 (defun widget-documentation-link-add (widget from to)
2668   (widget-specify-doc widget from to)
2669   (when widget-documentation-links
2670     (let ((regexp widget-documentation-link-regexp)
2671           (predicate widget-documentation-link-p)
2672           (type widget-documentation-link-type)
2673           (buttons (widget-get widget :buttons)))
2674       (save-excursion
2675         (goto-char from)
2676         (while (re-search-forward regexp to t)
2677           (let ((name (match-string 1))
2678                 (begin (match-beginning 1))
2679                 (end (match-end 1)))
2680             (when (funcall predicate name)
2681               (push (widget-convert-button type begin end :value name)
2682                     buttons)))))
2683       (widget-put widget :buttons buttons)))
2684   (let ((indent (widget-get widget :indent)))
2685     (when (and indent (not (zerop indent)))
2686       (save-excursion
2687         (save-restriction
2688           (narrow-to-region from to)
2689           (goto-char (point-min))
2690           (while (search-forward "\n" nil t)
2691             (insert-char ?\  indent)))))))
2692
2693 ;;; The `documentation-string' Widget.
2694
2695 (define-widget 'documentation-string 'item
2696   "A documentation string."
2697   :format "%v"
2698   :action 'widget-documentation-string-action
2699   :value-delete 'widget-children-value-delete
2700   :value-create 'widget-documentation-string-value-create)
2701
2702 (defun widget-documentation-string-value-create (widget)
2703   ;; Insert documentation string.
2704   (let ((doc (widget-value widget))
2705         (indent (widget-get widget :indent))
2706         (shown (widget-get (widget-get widget :parent) :documentation-shown))
2707         (start (point)))
2708     (if (string-match "\n" doc)
2709         (let ((before (substring doc 0 (match-beginning 0)))
2710               (after (substring doc (match-beginning 0)))
2711               buttons)
2712           (insert before " ")
2713           (widget-documentation-link-add widget start (point))
2714           (push (widget-create-child-and-convert
2715                  widget 'visibility
2716                  :help-echo "Show or hide rest of the documentation."
2717                  :off "More"
2718                  :action 'widget-parent-action
2719                  shown)
2720                 buttons)
2721           (when shown
2722             (setq start (point))
2723             (when (and indent (not (zerop indent)))
2724               (insert-char ?\  indent))
2725             (insert after)
2726             (widget-documentation-link-add widget start (point)))
2727           (widget-put widget :buttons buttons))
2728       (insert doc)
2729       (widget-documentation-link-add widget start (point))))
2730   (insert "\n"))
2731
2732 (defun widget-documentation-string-action (widget &rest ignore)
2733   ;; Toggle documentation.
2734   (let ((parent (widget-get widget :parent)))
2735     (widget-put parent :documentation-shown
2736                 (not (widget-get parent :documentation-shown))))
2737   ;; Redraw.
2738   (widget-value-set widget (widget-value widget)))
2739
2740 ;;; The Sexp Widgets.
2741
2742 (define-widget 'const 'item
2743   "An immutable sexp."
2744   :prompt-value 'widget-const-prompt-value
2745   :format "%t\n%d")
2746
2747 (defun widget-const-prompt-value (widget prompt value unbound)
2748   ;; Return the value of the const.
2749   (widget-value widget))
2750
2751 (define-widget 'function-item 'const
2752   "An immutable function name."
2753   :format "%v\n%h"
2754   :documentation-property (lambda (symbol)
2755                             (condition-case nil
2756                                 (documentation symbol t)
2757                               (error nil))))
2758
2759 (define-widget 'variable-item 'const
2760   "An immutable variable name."
2761   :format "%v\n%h"
2762   :documentation-property 'variable-documentation)
2763
2764 (defvar widget-string-prompt-value-history nil
2765   "History of input to `widget-string-prompt-value'.")
2766
2767 (define-widget 'string 'editable-field
2768   "A string"
2769   :tag "String"
2770   :format "%{%t%}: %v"
2771   :complete-function 'ispell-complete-word
2772   :prompt-history 'widget-string-prompt-value-history)
2773
2774 (define-widget 'regexp 'string
2775   "A regular expression."
2776   :match 'widget-regexp-match
2777   :validate 'widget-regexp-validate
2778   :tag "Regexp")
2779
2780 (defun widget-regexp-match (widget value)
2781   ;; Match valid regexps.
2782   (and (stringp value)
2783        (condition-case nil
2784            (prog1 t
2785              (string-match value ""))
2786          (error nil))))
2787
2788 (defun widget-regexp-validate (widget)
2789   "Check that the value of WIDGET is a valid regexp."
2790   (let ((val (widget-value widget)))
2791     (condition-case data
2792         (prog1 nil
2793           (string-match val ""))
2794       (error (widget-put widget :error (error-message-string data))
2795              widget))))
2796
2797 (define-widget 'file 'string
2798   "A file widget.
2799 It will read a file name from the minibuffer when invoked."
2800   :prompt-value 'widget-file-prompt-value
2801   :format "%{%t%}: %v"
2802   :tag "File"
2803   :action 'widget-file-action)
2804
2805 (defun widget-file-prompt-value (widget prompt value unbound)
2806   ;; Read file from minibuffer.
2807   (abbreviate-file-name
2808    (if unbound
2809        (read-file-name prompt)
2810      (let ((prompt2 (format "%s (default %s) " prompt value))
2811            (dir (file-name-directory value))
2812            (file (file-name-nondirectory value))
2813            (must-match (widget-get widget :must-match)))
2814        (read-file-name prompt2 dir nil must-match file)))))
2815
2816 (defun widget-file-action (widget &optional event)
2817   ;; Read a file name from the minibuffer.
2818   (let* ((value (widget-value widget))
2819          (dir (file-name-directory value))
2820          (file (file-name-nondirectory value))
2821          (menu-tag (widget-apply widget :menu-tag-get))
2822          (must-match (widget-get widget :must-match))
2823          (answer (read-file-name (concat menu-tag ": (default `" value "') ")
2824                                  dir nil must-match file)))
2825     (widget-value-set widget (abbreviate-file-name answer))
2826     (widget-setup)
2827     (widget-apply widget :notify widget event)))
2828
2829 (define-widget 'directory 'file
2830   "A directory widget.
2831 It will read a directory name from the minibuffer when invoked."
2832   :tag "Directory")
2833
2834 (defvar widget-symbol-prompt-value-history nil
2835   "History of input to `widget-symbol-prompt-value'.")
2836
2837 (define-widget 'symbol 'editable-field
2838   "A lisp symbol."
2839   :value nil
2840   :tag "Symbol"
2841   :format "%{%t%}: %v"
2842   :match (lambda (widget value) (symbolp value))
2843   :prompt-internal 'widget-symbol-prompt-internal
2844   :prompt-match 'symbolp
2845   :prompt-history 'widget-symbol-prompt-value-history
2846   :value-to-internal (lambda (widget value)
2847                        (if (symbolp value)
2848                            (symbol-name value)
2849                          value))
2850   :value-to-external (lambda (widget value)
2851                        (if (stringp value)
2852                            (intern value)
2853                          value)))
2854
2855 (defun widget-symbol-prompt-internal (widget prompt initial history)
2856   ;; Read file from minibuffer.
2857   (let ((answer (completing-read prompt obarray
2858                                  (widget-get widget :prompt-match)
2859                                  nil initial history)))
2860     (if (and (stringp answer)
2861              (not (zerop (length answer))))
2862         answer
2863       (error "No value"))))
2864
2865 (defvar widget-function-prompt-value-history nil
2866   "History of input to `widget-function-prompt-value'.")
2867
2868 (define-widget 'function 'sexp
2869   "A lisp function."
2870   :complete-function 'lisp-complete-symbol
2871   :prompt-value 'widget-field-prompt-value
2872   :prompt-internal 'widget-symbol-prompt-internal
2873   :prompt-match 'fboundp
2874   :prompt-history 'widget-function-prompt-value-history
2875   :action 'widget-field-action
2876   :tag "Function")
2877
2878 (defvar widget-variable-prompt-value-history nil
2879   "History of input to `widget-variable-prompt-value'.")
2880
2881 (define-widget 'variable 'symbol
2882   ;; Should complete on variables.
2883   "A lisp variable."
2884   :prompt-match 'boundp
2885   :prompt-history 'widget-variable-prompt-value-history
2886   :tag "Variable")
2887
2888 (when (featurep 'mule)
2889   (defvar widget-coding-system-prompt-value-history nil
2890     "History of input to `widget-coding-system-prompt-value'.")
2891
2892   (define-widget 'coding-system 'symbol
2893     "A MULE coding-system."
2894     :format "%{%t%}: %v"
2895     :tag "Coding system"
2896     :prompt-history 'widget-coding-system-prompt-value-history
2897     :prompt-value 'widget-coding-system-prompt-value
2898     :action 'widget-coding-system-action)
2899
2900   (defun widget-coding-system-prompt-value (widget prompt value unbound)
2901     ;; Read coding-system from minibuffer.
2902     (intern
2903      (completing-read (format "%s (default %s) " prompt value)
2904                       (mapcar (function
2905                                (lambda (sym)
2906                                  (list (symbol-name sym))
2907                                  ))
2908                               (coding-system-list)))))
2909
2910   (defun widget-coding-system-action (widget &optional event)
2911     ;; Read a file name from the minibuffer.
2912     (let ((answer
2913            (widget-coding-system-prompt-value
2914             widget
2915             (widget-apply widget :menu-tag-get)
2916             (widget-value widget)
2917             t)))
2918       (widget-value-set widget answer)
2919       (widget-apply widget :notify widget event)
2920       (widget-setup)))
2921   )
2922
2923 (define-widget 'sexp 'editable-field
2924   "An arbitrary lisp expression."
2925   :tag "Lisp expression"
2926   :format "%{%t%}: %v"
2927   :value nil
2928   :validate 'widget-sexp-validate
2929   :match (lambda (widget value) t)
2930   :value-to-internal 'widget-sexp-value-to-internal
2931   :value-to-external (lambda (widget value) (read value))
2932   :prompt-history 'widget-sexp-prompt-value-history
2933   :prompt-value 'widget-sexp-prompt-value)
2934
2935 (defun widget-sexp-value-to-internal (widget value)
2936   ;; Use pp for printer representation.
2937   (let ((pp (if (symbolp value)
2938                 (prin1-to-string value)
2939               (pp-to-string value))))
2940     (while (string-match "\n\\'" pp)
2941       (setq pp (substring pp 0 -1)))
2942     (if (or (string-match "\n\\'" pp)
2943             (> (length pp) 40))
2944         (concat "\n" pp)
2945       pp)))
2946
2947 (defun widget-sexp-validate (widget)
2948   ;; Valid if we can read the string and there is no junk left after it.
2949   (save-excursion
2950     (let ((buffer (set-buffer (get-buffer-create " *Widget Scratch*"))))
2951       (erase-buffer)
2952       (insert (widget-apply widget :value-get))
2953       (goto-char (point-min))
2954       (condition-case data
2955           (let ((value (read buffer)))
2956             (if (eobp)
2957                 (if (widget-apply widget :match value)
2958                     nil
2959                   (widget-put widget :error (widget-get widget :type-error))
2960                   widget)
2961               (widget-put widget
2962                           :error (format "Junk at end of expression: %s"
2963                                          (buffer-substring (point)
2964                                                            (point-max))))
2965               widget))
2966         (error (widget-put widget :error (error-message-string data))
2967                widget)))))
2968
2969 (defvar widget-sexp-prompt-value-history nil
2970   "History of input to `widget-sexp-prompt-value'.")
2971
2972 (defun widget-sexp-prompt-value (widget prompt value unbound)
2973   ;; Read an arbitrary sexp.
2974   (let ((found (read-string prompt
2975                             (if unbound nil (cons (prin1-to-string value) 0))
2976                             (widget-get widget :prompt-history))))
2977     (save-excursion
2978       (let ((buffer (set-buffer (get-buffer-create " *Widget Scratch*"))))
2979         (erase-buffer)
2980         (insert found)
2981         (goto-char (point-min))
2982         (let ((answer (read buffer)))
2983           (unless (eobp)
2984             (error "Junk at end of expression: %s"
2985                    (buffer-substring (point) (point-max))))
2986           answer)))))
2987
2988 (define-widget 'integer 'sexp
2989   "An integer."
2990   :tag "Integer"
2991   :value 0
2992   :type-error "This field should contain an integer"
2993   :value-to-internal (lambda (widget value)
2994                        (if (integerp value)
2995                            (prin1-to-string value)
2996                          value))
2997   :match (lambda (widget value) (integerp value)))
2998
2999 (define-widget 'character 'editable-field
3000   "An character."
3001   :tag "Character"
3002   :value 0
3003   :size 1
3004   :format "%{%t%}: %v\n"
3005   :valid-regexp "\\`.\\'"
3006   :error "This field should contain a single character"
3007   :value-to-internal (lambda (widget value)
3008                        (if (stringp value)
3009                            value
3010                          (char-to-string value)))
3011   :value-to-external (lambda (widget value)
3012                        (if (stringp value)
3013                            (aref value 0)
3014                          value))
3015   :match (lambda (widget value)
3016            (if (fboundp 'characterp)
3017                (characterp value)
3018              (integerp value))))
3019
3020 (define-widget 'number 'sexp
3021   "A floating point number."
3022   :tag "Number"
3023   :value 0.0
3024   :type-error "This field should contain a number"
3025   :value-to-internal (lambda (widget value)
3026                        (if (numberp value)
3027                            (prin1-to-string value)
3028                          value))
3029   :match (lambda (widget value) (numberp value)))
3030
3031 (define-widget 'list 'group
3032   "A lisp list."
3033   :tag "List"
3034   :format "%{%t%}:\n%v")
3035
3036 (define-widget 'vector 'group
3037   "A lisp vector."
3038   :tag "Vector"
3039   :format "%{%t%}:\n%v"
3040   :match 'widget-vector-match
3041   :value-to-internal (lambda (widget value) (append value nil))
3042   :value-to-external (lambda (widget value) (apply 'vector value)))
3043
3044 (defun widget-vector-match (widget value)
3045   (and (vectorp value)
3046        (widget-group-match widget
3047                            (widget-apply widget :value-to-internal value))))
3048
3049 (define-widget 'cons 'group
3050   "A cons-cell."
3051   :tag "Cons-cell"
3052   :format "%{%t%}:\n%v"
3053   :match 'widget-cons-match
3054   :value-to-internal (lambda (widget value)
3055                        (list (car value) (cdr value)))
3056   :value-to-external (lambda (widget value)
3057                        (cons (nth 0 value) (nth 1 value))))
3058
3059 (defun widget-cons-match (widget value)
3060   (and (consp value)
3061        (widget-group-match widget
3062                            (widget-apply widget :value-to-internal value))))
3063
3064 (define-widget 'choice 'menu-choice
3065   "A union of several sexp types."
3066   :tag "Choice"
3067   :format "%{%t%}: %[Value Menu%] %v"
3068   :button-prefix 'widget-push-button-prefix
3069   :button-suffix 'widget-push-button-suffix
3070   :prompt-value 'widget-choice-prompt-value)
3071
3072 (defun widget-choice-prompt-value (widget prompt value unbound)
3073   "Make a choice."
3074   (let ((args (widget-get widget :args))
3075         (completion-ignore-case (widget-get widget :case-fold))
3076         current choices old)
3077     ;; Find the first arg that match VALUE.
3078     (let ((look args))
3079       (while look
3080         (if (widget-apply (car look) :match value)
3081             (setq old (car look)
3082                   look nil)
3083           (setq look (cdr look)))))
3084     ;; Find new choice.
3085     (setq current
3086           (cond ((= (length args) 0)
3087                  nil)
3088                 ((= (length args) 1)
3089                  (nth 0 args))
3090                 ((and (= (length args) 2)
3091                       (memq old args))
3092                  (if (eq old (nth 0 args))
3093                      (nth 1 args)
3094                    (nth 0 args)))
3095                 (t
3096                  (while args
3097                    (setq current (car args)
3098                          args (cdr args))
3099                    (setq choices
3100                          (cons (cons (widget-apply current :menu-tag-get)
3101                                      current)
3102                                choices)))
3103                  (let ((val (completing-read prompt choices nil t)))
3104                    (if (stringp val)
3105                        (let ((try (try-completion val choices)))
3106                          (when (stringp try)
3107                            (setq val try))
3108                          (cdr (assoc val choices)))
3109                      nil)))))
3110     (if current
3111         (widget-prompt-value current prompt nil t)
3112       value)))
3113
3114 (define-widget 'radio 'radio-button-choice
3115   "A union of several sexp types."
3116   :tag "Choice"
3117   :format "%{%t%}:\n%v"
3118   :prompt-value 'widget-choice-prompt-value)
3119
3120 (define-widget 'repeat 'editable-list
3121   "A variable length homogeneous list."
3122   :tag "Repeat"
3123   :format "%{%t%}:\n%v%i\n")
3124
3125 (define-widget 'set 'checklist
3126   "A list of members from a fixed set."
3127   :tag "Set"
3128   :format "%{%t%}:\n%v")
3129
3130 (define-widget 'boolean 'toggle
3131   "To be nil or non-nil, that is the question."
3132   :tag "Boolean"
3133   :prompt-value 'widget-boolean-prompt-value
3134   :button-prefix 'widget-push-button-prefix
3135   :button-suffix 'widget-push-button-suffix
3136   :format "%{%t%}: %[Toggle%]  %v\n"
3137   :on "on (non-nil)"
3138   :off "off (nil)")
3139
3140 (defun widget-boolean-prompt-value (widget prompt value unbound)
3141   ;; Toggle a boolean.
3142   (y-or-n-p prompt))
3143
3144 ;;; The `color' Widget.
3145
3146 (define-widget 'color-item 'choice-item
3147   "A color name (with sample)."
3148   :format "%v (%{sample%})\n"
3149   :sample-face-get 'widget-color-item-button-face-get)
3150
3151 (defun widget-color-item-button-face-get (widget)
3152   (let ((symbol (intern (concat "fg:" (widget-value widget)))))
3153     (if (string-match "XEmacs" emacs-version)
3154         (prog1 symbol
3155           (or (find-face symbol)
3156               (set-face-foreground (make-face symbol) (widget-value widget))))
3157       (condition-case nil
3158           (facemenu-get-face symbol)
3159         (error 'default)))))
3160
3161 (define-widget 'color 'push-button
3162   "Choose a color name (with sample)."
3163   :format "%[%t%]: %v"
3164   :tag "Color"
3165   :value "black"
3166   :value-create 'widget-color-value-create
3167   :value-delete 'widget-children-value-delete
3168   :value-get 'widget-color-value-get
3169   :value-set 'widget-color-value-set
3170   :action 'widget-color-action
3171   :match 'widget-field-match
3172   :tag "Color")
3173
3174 (defvar widget-color-choice-list nil)
3175 ;; Variable holding the possible colors.
3176
3177 (defun widget-color-choice-list ()
3178   (unless widget-color-choice-list
3179     (setq widget-color-choice-list
3180           (mapcar '(lambda (color) (list color))
3181                   (x-defined-colors))))
3182   widget-color-choice-list)
3183
3184 (defun widget-color-value-create (widget)
3185   (let ((child (widget-create-child-and-convert
3186                 widget 'color-item (widget-get widget :value))))
3187     (widget-put widget :children (list child))))
3188
3189 (defun widget-color-value-get (widget)
3190   ;; Pass command to first child.
3191   (widget-apply (car (widget-get widget :children)) :value-get))
3192
3193 (defun widget-color-value-set (widget value)
3194   ;; Pass command to first child.
3195   (widget-apply (car (widget-get widget :children)) :value-set value))
3196
3197 (defvar widget-color-history nil
3198   "History of entered colors")
3199
3200 (defun widget-color-action (widget &optional event)
3201   ;; Prompt for a color.
3202   (let* ((tag (widget-apply widget :menu-tag-get))
3203          (prompt (concat tag ": "))
3204          (answer (cond ((string-match "XEmacs" emacs-version)
3205                         (read-color prompt))
3206                        ((fboundp 'x-defined-colors)
3207                         (completing-read (concat tag ": ")
3208                                          (widget-color-choice-list)
3209                                          nil nil nil 'widget-color-history))
3210                        (t
3211                         (read-string prompt (widget-value widget))))))
3212     (unless (zerop (length answer))
3213       (widget-value-set widget answer)
3214       (widget-setup)
3215       (widget-apply widget :notify widget event))))
3216
3217 ;;; The Help Echo
3218
3219 (defun widget-echo-help-mouse ()
3220   "Display the help message for the widget under the mouse.
3221 Enable with (run-with-idle-timer 1 t 'widget-echo-help-mouse)"
3222   (let* ((pos (mouse-position))
3223          (frame (car pos))
3224          (x (car (cdr pos)))
3225          (y (cdr (cdr pos)))
3226          (win (window-at x y frame))
3227          (where (coordinates-in-window-p (cons x y) win)))
3228     (when (consp where)
3229       (save-window-excursion
3230         (progn ; save-excursion
3231           (select-window win)
3232           (let* ((result (compute-motion (window-start win)
3233                                          '(0 . 0)
3234                                          (window-end win)
3235                                          where
3236                                          (window-width win)
3237                                          (cons (window-hscroll) 0)
3238                                          win)))
3239             (when (and (eq (nth 1 result) x)
3240                        (eq (nth 2 result) y))
3241               (widget-echo-help (nth 0 result))))))))
3242   (unless track-mouse
3243     (setq track-mouse t)
3244     (add-hook 'post-command-hook 'widget-stop-mouse-tracking)))
3245
3246 (defun widget-stop-mouse-tracking (&rest args)
3247   "Stop the mouse tracking done while idle."
3248   (remove-hook 'post-command-hook 'widget-stop-mouse-tracking)
3249   (setq track-mouse nil))
3250
3251 (defun widget-at (pos)
3252   "The button or field at POS."
3253   (or (get-char-property pos 'button)
3254       (get-char-property pos 'field)))
3255
3256 (defun widget-echo-help (pos)
3257   "Display the help echo for widget at POS."
3258   (let* ((widget (widget-at pos))
3259          (help-echo (and widget (widget-get widget :help-echo))))
3260     (cond ((stringp help-echo)
3261            (message "%s" help-echo))
3262           ((and (symbolp help-echo) (fboundp help-echo)
3263                 (stringp (setq help-echo (funcall help-echo widget))))
3264            (message "%s" help-echo)))))
3265
3266 ;;; The End:
3267
3268 (provide 'wid-edit)
3269
3270 ;; wid-edit.el ends here