[Emacs-diffs] Changes to emacs/man/widget.texi [gnus-5_10-branch]

[Miles Bader]

Index: emacs/man/widget.texi
diff -c /dev/null emacs/man/widget.texi:1.26.2.1
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--- 1,1811 ----
+ \input texinfo.tex
+ 
+ @c %**start of header
+ @setfilename ../info/widget
+ @settitle The Emacs Widget Library
+ @syncodeindex fn cp
+ @syncodeindex vr cp
+ @syncodeindex ky cp
+ @afourpaper
+ @c %**end of header
+ 
+ @copying
+ Copyright @copyright{} 2000, 2002, 2003 Free Software Foundation, Inc.
+ 
+ @quotation
+ Permission is granted to copy, distribute and/or modify this document
+ under the terms of the GNU Free Documentation License, Version 1.1 or
+ any later version published by the Free Software Foundation; with the
+ Invariant Sections being ``The GNU Manifesto'', ``Distribution'' and
+ ``GNU GENERAL PUBLIC LICENSE'', with the Front-Cover texts being ``A GNU
+ Manual'', and with the Back-Cover Texts as in (a) below.  A copy of the
+ license is included in the section entitled ``GNU Free Documentation
+ License'' in the Emacs manual.
+ 
+ This document is part of a collection distributed under the GNU Free
+ Documentation License.  If you want to distribute this document
+ separately from the collection, you can do so by adding a copy of the
+ license to the document, as described in section 6 of the license.
+ 
+ (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
+ this GNU Manual, like GNU software.  Copies published by the Free
+ Software Foundation raise funds for GNU development.''
+ @end quotation
+ @end copying
+ 
+ @dircategory Emacs
+ @direntry
+ * Widget: (widget).      The "widget" package used by the Emacs Customization
+                            facility.
+ @end direntry
+ 
+ @node Top, Introduction, (dir), (dir)
+ @comment  node-name,  next,  previous,  up
+ @top The Emacs Widget Library
+ 
+ @menu
+ * Introduction::
+ * User Interface::
+ * Programming Example::
+ * Setting Up the Buffer::
+ * Basic Types::
+ * Sexp Types::
+ * Widget Properties::
+ * Defining New Widgets::
+ * Widget Browser::
+ * Widget Minor Mode::
+ * Utilities::
+ * Widget Wishlist::
+ * Index::
+ @end menu
+ 
+ @node  Introduction, User Interface, Top, Top
+ @comment  node-name,  next,  previous,  up
+ @section Introduction
+ 
+ Most graphical user interface toolkits provide a number of standard
+ user interface controls (sometimes known as `widgets' or `gadgets').
+ Emacs doesn't really support anything like this, except for an
+ incredibly powerful text ``widget.''  On the other hand, Emacs does
+ provide the necessary primitives to implement many other widgets
+ within a text buffer.  The @code{widget} package simplifies this task.
+ 
+ @cindex basic widgets
+ @cindex widgets, basic types
+ The basic widgets are:
+ 
+ @table @code
+ @item link
+ Areas of text with an associated action.  Intended for hypertext links
+ embedded in text.
+ @item push-button
+ Like link, but intended for stand-alone buttons.
+ @item editable-field
+ An editable text field.  It can be either variable or fixed length.
+ @item menu-choice
+ Allows the user to choose one of multiple options from a menu, each
+ option is itself a widget.  Only the selected option will be visible in
+ the buffer.
+ @item radio-button-choice
+ Allows the user to choose one of multiple options by activating radio
+ buttons.  The options are implemented as widgets.  All options will be
+ visible in the buffer.
+ @item item
+ A simple constant widget intended to be used in the @code{menu-choice} and
+ @code{radio-button-choice} widgets.
+ @item choice-item
+ A button item only intended for use in choices.  When invoked, the user
+ will be asked to select another option from the choice widget.
+ @item toggle
+ A simple @samp{on}/@samp{off} switch.
+ @item checkbox
+ A checkbox (@samp{[ ]}/@samp{[X]}).
+ @item editable-list
+ Create an editable list.  The user can insert or delete items in the
+ list.  Each list item is itself a widget.
+ @end table
+ 
+ Now, of what possible use can support for widgets be in a text editor?
+ I'm glad you asked.  The answer is that widgets are useful for
+ implementing forms.  A @dfn{form} in Emacs is a buffer where the user is
+ supposed to fill out a number of fields, each of which has a specific
+ meaning.  The user is not supposed to change or delete any of the text
+ between the fields.  Examples of forms in Emacs are the @file{forms}
+ package (of course), the customize buffers, the mail and news compose
+ modes, and the @acronym{HTML} form support in the @file{w3} browser.
+ 
+ @cindex widget library, why use it
+ The advantages for a programmer of using the @code{widget} package to
+ implement forms are:
+ 
+ @enumerate
+ @item
+ More complex fields than just editable text are supported.
+ @item
+ You can give the users immediate feedback if they enter invalid data in a
+ text field, and sometimes prevent entering invalid data.
+ @item
+ You can have fixed sized fields, thus allowing multiple fields to be
+ lined up in columns.
+ @item
+ It is simple to query or set the value of a field.
+ @item
+ Editing happens in the buffer, not in the mini-buffer.
+ @item
+ Packages using the library get a uniform look, making them easier for
+ the user to learn.
+ @item
+ As support for embedded graphics improve, the widget library will be
+ extended to use the GUI features.  This means that your code using the
+ widget library will also use the new graphic features automatically.
+ @end enumerate
+ 
+ In order to minimize the code that is loaded by users who does not
+ create any widgets, the code has been split in two files:
+ 
+ @cindex widget library, files
+ @table @file
+ @item widget.el
+ This will declare the user variables, define the function
+ @code{define-widget}, and autoload the function @code{widget-create}.
+ @item wid-edit.el
+ Everything else is here, there is no reason to load it explicitly, as
+ it will be autoloaded when needed.
+ @end table
+ 
+ @node User Interface, Programming Example, Introduction, Top
+ @comment  node-name,  next,  previous,  up
+ @section User Interface
+ 
+ A form consist of read only text for documentation and some fields,
+ where each field contains two parts, a tag and a value.  The tags are
+ used to identify the fields, so the documentation can refer to the
+ @samp{foo field}, meaning the field tagged with @samp{Foo}. Here is an
+ example form:
+ 
+ @example
+ Here is some documentation.
+ 
+ Name: @i{My Name}     @strong{Choose}: This option
+ Address:  @i{Some Place
+ In some City
+ Some country.}
+ 
+ See also @b{_other work_} for more information.
+ 
+ Numbers: count to three below
+ @b{[INS]} @b{[DEL]} @i{One}
+ @b{[INS]} @b{[DEL]} @i{Eh, two?}
+ @b{[INS]} @b{[DEL]} @i{Five!}
+ @b{[INS]}
+ 
+ Select multiple:
+ 
+ @b{[X]} This
+ @b{[ ]} That
+ @b{[X]} Thus
+ 
+ Select one:
+ 
+ @b{(*)} One
+ @b{( )} Another One.
+ @b{( )} A Final One.
+ 
+ @b{[Apply Form]} @b{[Reset Form]}
+ @end example
+ 
+ The top level widgets in is example are tagged @samp{Name},
+ @samp{Choose}, @samp{Address}, @samp{_other work_}, @samp{Numbers},
+ @samp{Select multiple}, @samp{Select one}, @samp{[Apply Form]}, and
+ @samp{[Reset Form]}.  There are basically two things the user can do
+ within a form, namely editing the editable text fields and activating
+ the buttons.
+ 
+ @subsection Editable Text Fields
+ 
+ In the example, the value for the @samp{Name} is most likely displayed
+ in an editable text field, and so are values for each of the members of
+ the @samp{Numbers} list.  All the normal Emacs editing operations are
+ available for editing these fields.  The only restriction is that each
+ change you make must be contained within a single editable text field.
+ For example, capitalizing all text from the middle of one field to the
+ middle of another field is prohibited.
+ 
+ Editable text fields are created by the @code{editable-field} widget.
+ 
+ @strong{Warning:} In an @code{editable-field} widget, the editable
+ field must not be adjacent to another widget---that won't work.
+ You must put some text in between.  Either make this text part of
+ the @code{editable-field} widget itself, or insert it with
+ @code{widget-insert}.
+ 
+ The @code{:format} keyword is useful for generating the necessary
+ text; for instance, if you give it a value of @code{"Name: %v "},
+ the @samp{Name: } part will provide the necessary separating text
+ before the field and the trailing space will provide the
+ separating text after the field.  If you don't include the
+ @code{:size} keyword, the field will extend to the end of the
+ line, and the terminating newline will provide separation after.
+ 
+ The editing text fields are highlighted with the
+ @code{widget-field-face} face, making them easy to find.
+ 
+ @deffn Face widget-field-face
+ Face used for other editing fields.
+ @end deffn
+ 
+ @subsection Buttons
+ 
+ @cindex widget buttons
+ @cindex button widgets
+ Some portions of the buffer have an associated @dfn{action}, which can
+ be @dfn{invoked} by a standard key or mouse command.  These portions
+ are called @dfn{buttons}.  The default commands for activating a button
+ are:
+ 
+ @table @kbd
+ @item @key{RET}
+ @deffn Command widget-button-press @var{pos} &optional @var{event}
+ Invoke the button at @var{pos}, defaulting to point.
+ If point is not located on a button, invoke the binding in
+ @code{widget-global-map} (by default the global map).
+ @end deffn
+ 
+ @kindex Mouse-2 @r{(on button widgets})
+ @item Mouse-2
+ @deffn Command widget-button-click @var{event}
+ Invoke the button at the location of the mouse pointer.  If the mouse
+ pointer is located in an editable text field, invoke the binding in
+ @code{widget-global-map} (by default the global map).
+ @end deffn
+ @end table
+ 
+ There are several different kind of buttons, all of which are present in
+ the example:
+ 
+ @table @emph
+ @cindex option field tag
+ @item The Option Field Tags
+ When you invoke one of these buttons, you will be asked to choose
+ between a number of different options.  This is how you edit an option
+ field.  Option fields are created by the @code{menu-choice} widget.  In
+ the example, @address@hidden is an option field tag.
+ @item The @address@hidden and @address@hidden buttons
+ Activating these will insert or delete elements from an editable list.
+ The list is created by the @code{editable-list} widget.
+ @cindex embedded buttons
+ @item Embedded Buttons
+ The @address@hidden work_}} is an example of an embedded
+ button.  Embedded buttons are not associated with a fields, but can serve
+ any purpose, such as implementing hypertext references.  They are
+ usually created by the @code{link} widget.
+ @item The @address@hidden ]}} and @address@hidden buttons
+ Activating one of these will convert it to the other.  This is useful
+ for implementing multiple-choice fields.  You can create it with the
+ @code{checkbox} widget.
+ @item The @address@hidden( )}} and @address@hidden(*)}} buttons
+ Only one radio button in a @code{radio-button-choice} widget can be
+ selected at any time.  When you invoke one of the unselected radio
+ buttons, it will be selected and the previous selected radio button will
+ become unselected.
+ @item The @address@hidden Form]}} @address@hidden Form]}} buttons
+ These are explicit buttons made with the @code{push-button} widget.  The
+ main difference from the @code{link} widget is that the buttons will be
+ displayed as GUI buttons when possible.
+ @end table
+ 
+ To make them easier to locate, buttons are emphasized in the buffer.
+ 
+ @deffn Face widget-button-face
+ Face used for buttons.
+ @end deffn
+ 
+ @defopt widget-mouse-face
+ Face used for highlighting a button when the mouse pointer moves across
+ it.
+ @end defopt
+ 
+ @subsection Navigation
+ 
+ You can use all the normal Emacs commands to move around in a form
+ buffer, plus you will have these additional commands:
+ 
+ @table @kbd
+ @item @key{TAB}
+ @deffn Command widget-forward &optional count
+ Move point @var{count} buttons or editing fields forward.
+ @end deffn
+ @item @key{M-TAB}
+ @deffn Command widget-backward &optional count
+ Move point @var{count} buttons or editing fields backward.
+ @end deffn
+ @end table
+ 
+ @node Programming Example, Setting Up the Buffer, User Interface, Top
+ @comment  node-name,  next,  previous,  up
+ @section Programming Example
+ 
+ @cindex widgets, programming example
+ @cindex example of using widgets
+ Here is the code to implement the user interface example (@pxref{User
+ Interface}).
+ 
+ @lisp
+ (require 'widget)
+ 
+ (eval-when-compile
+   (require 'wid-edit))
+ 
+ (defvar widget-example-repeat)
+ 
+ (defun widget-example ()
+   "Create the widgets from the Widget manual."
+   (interactive)
+   (switch-to-buffer "*Widget Example*")
+   (kill-all-local-variables)
+   (make-local-variable 'widget-example-repeat)
+   (let ((inhibit-read-only t))
+     (erase-buffer))
+   (remove-overlays)
+   (widget-insert "Here is some documentation.\n\nName: ")
+   (widget-create 'editable-field
+                :size 13
+                :format "%v " ; Text after the field!
+                "My Name")
+   (widget-create 'menu-choice
+                :tag "Choose"
+                :value "This"
+                :help-echo "Choose me, please!"
+                :notify (lambda (widget &rest ignore)
+                          (message "%s is a good choice!"
+                                   (widget-value widget)))
+                '(item :tag "This option" :value "This")
+                '(choice-item "That option")
+                '(editable-field :menu-tag "No option" "Thus option"))
+   (widget-insert "Address: ")
+   (widget-create 'editable-field
+                "Some Place\nIn some City\nSome country.")
+   (widget-insert "\nSee also ")
+   (widget-create 'link
+                :notify (lambda (&rest ignore)
+                          (widget-value-set widget-example-repeat
+                                            '("En" "To" "Tre"))
+                          (widget-setup))
+                "other work")
+   (widget-insert
+     " for more information.\n\nNumbers: count to three below\n")
+   (setq widget-example-repeat
+       (widget-create 'editable-list
+                      :entry-format "%i %d %v"
+                      :notify (lambda (widget &rest ignore)
+                                (let ((old (widget-get widget
+                                                       ':example-length))
+                                      (new (length (widget-value widget))))
+                                  (unless (eq old new)
+                                    (widget-put widget ':example-length new)
+                                    (message "You can count to %d." new))))
+                      :value '("One" "Eh, two?" "Five!")
+                      '(editable-field :value "three")))
+   (widget-insert "\n\nSelect multiple:\n\n")
+   (widget-create 'checkbox t)
+   (widget-insert " This\n")
+   (widget-create 'checkbox nil)
+   (widget-insert " That\n")
+   (widget-create 'checkbox
+                :notify (lambda (&rest ignore) (message "Tickle"))
+                t)
+   (widget-insert " Thus\n\nSelect one:\n\n")
+   (widget-create 'radio-button-choice
+                :value "One"
+                :notify (lambda (widget &rest ignore)
+                          (message "You selected %s"
+                                   (widget-value widget)))
+                '(item "One") '(item "Another One.") '(item "A Final One."))
+   (widget-insert "\n")
+   (widget-create 'push-button
+                :notify (lambda (&rest ignore)
+                          (if (= (length (widget-value widget-example-repeat))
+                                 3)
+                              (message "Congratulation!")
+                            (error "Three was the count!")))
+                "Apply Form")
+   (widget-insert " ")
+   (widget-create 'push-button
+                :notify (lambda (&rest ignore)
+                          (widget-example))
+                "Reset Form")
+   (widget-insert "\n")
+   (use-local-map widget-keymap)
+   (widget-setup))
+ @end lisp
+ 
+ @node Setting Up the Buffer, Basic Types, Programming Example, Top
+ @comment  node-name,  next,  previous,  up
+ @section Setting Up the Buffer
+ 
+ Widgets are created with @code{widget-create}, which returns a
+ @dfn{widget} object.  This object can be queried and manipulated by
+ other widget functions, until it is deleted with @code{widget-delete}.
+ After the widgets have been created, @code{widget-setup} must be called
+ to enable them.
+ 
+ @defun widget-create type [ keyword argument address@hidden
+ Create and return a widget of type @var{type}.
+ The syntax for the @var{type} argument is described in @ref{Basic Types}.
+ 
+ The keyword arguments can be used to overwrite the keyword arguments
+ that are part of @var{type}.
+ @end defun
+ 
+ @defun widget-delete widget
+ Delete @var{widget} and remove it from the buffer.
+ @end defun
+ 
+ @defun widget-setup
+ Set up a buffer to support widgets.
+ 
+ This should be called after creating all the widgets and before allowing
+ the user to edit them.
+ @refill
+ @end defun
+ 
+ If you want to insert text outside the widgets in the form, the
+ recommended way to do that is with @code{widget-insert}.
+ 
+ @defun widget-insert
+ Insert the arguments, either strings or characters, at point.
+ The inserted text will be read-only.
+ @end defun
+ 
+ There is a standard widget keymap which you might find useful.
+ 
+ @findex widget-button-press
+ @findex widget-button-click
+ @defvr Const widget-keymap
+ A keymap with the global keymap as its address@hidden
+ @key{TAB} and @address@hidden are bound to @code{widget-forward} and
+ @code{widget-backward}, respectively.  @key{RET} and @kbd{Mouse-2}
+ are bound to @code{widget-button-press} and
+ @address@hidden
+ @end defvr
+ 
+ @defvar widget-global-map
+ Keymap used by @code{widget-button-press} and @code{widget-button-click}
+ when not on a button.  By default this is @code{global-map}.
+ @end defvar
+ 
+ @node Basic Types, Sexp Types, Setting Up the Buffer, Top
+ @comment  node-name,  next,  previous,  up
+ @section Basic Types
+ 
+ The syntax of a type specification is given below:
+ 
+ @example
+ NAME ::= (NAME [KEYWORD ARGUMENT]... ARGS)
+      |   NAME
+ @end example
+ 
+ Where, @var{name} is a widget name, @var{keyword} is the name of a
+ property, @var{argument} is the value of the property, and @var{args}
+ are interpreted in a widget specific way.
+ 
+ @cindex keyword arguments
+ The following keyword arguments that apply to all widgets:
+ 
+ @table @code
+ @vindex address@hidden keyword}
+ @item :value
+ The initial value for widgets of this type.
+ 
+ @vindex address@hidden keyword}
+ @item :format
+ This string will be inserted in the buffer when you create a widget.
+ The following @samp{%} escapes are available:
+ 
+ @table @samp
+ @item %[
+ @itemx %]
+ The text inside will be marked as a button.
+ 
+ By default, the text will be shown in @code{widget-button-face}, and
+ surrounded by brackets.
+ 
+ @defopt widget-button-prefix
+ String to prefix buttons.
+ @end defopt
+ 
+ @defopt widget-button-suffix
+ String to suffix buttons.
+ @end defopt
+ 
+ @item address@hidden
+ @itemx address@hidden
+ The text inside will be displayed with the face specified by
+ @code{:sample-face}.
+ 
+ @item %v
+ This will be replaced with the buffer representation of the widget's
+ value.  What this is depends on the widget type.
+ 
+ @item %d
+ Insert the string specified by @code{:doc} here.
+ 
+ @item %h
+ Like @samp{%d}, with the following modifications: If the documentation
+ string is more than one line, it will add a button which will toggle
+ between showing only the first line, and showing the full text.
+ Furthermore, if there is no @code{:doc} property in the widget, it will
+ instead examine the @code{:documentation-property} property.  If it is a
+ lambda expression, it will be called with the widget's value as an
+ argument, and the result will be used as the documentation text.
+ 
+ @item %t
+ Insert the string specified by @code{:tag} here, or the @code{princ}
+ representation of the value if there is no tag.
+ 
+ @item %%
+ Insert a literal @samp{%}.
+ @end table
+ 
+ @vindex address@hidden keyword}
+ @item :button-face
+ Face used to highlight text inside %[ %] in the format.
+ 
+ @vindex address@hidden keyword}
+ @vindex address@hidden keyword}
+ @item :button-prefix
+ @itemx :button-suffix
+ Text around %[ %] in the format.
+ 
+ These can be
+ @table @emph
+ @item nil
+ No text is inserted.
+ 
+ @item a string
+ The string is inserted literally.
+ 
+ @item a symbol
+ The value of the symbol is expanded according to this table.
+ @end table
+ 
+ @vindex address@hidden keyword}
+ @item :doc
+ The string inserted by the @samp{%d} escape in the format
+ string.
+ 
+ @vindex address@hidden keyword}
+ @item :tag
+ The string inserted by the @samp{%t} escape in the format
+ string.
+ 
+ @vindex address@hidden keyword}
+ @item :tag-glyph
+ Name of image to use instead of the string specified by @code{:tag} on
+ Emacsen that supports it.
+ 
+ @vindex address@hidden keyword}
+ @item :help-echo
+ Specifies how to display a message whenever you move to the widget with
+ either @code{widget-forward} or @code{widget-backward} or move the mouse
+ over it (using the standard @code{help-echo} mechanism).  The argument
+ is either a string to display, a function of one argument, the widget,
+ which should return a string to display, or a form that evaluates to
+ such a string.
+ 
+ @vindex address@hidden keyword}
+ @item :indent
+ An integer indicating the absolute number of spaces to indent children
+ of this widget.
+ 
+ @vindex address@hidden keyword}
+ @item :offset
+ An integer indicating how many extra spaces to add to the widget's
+ grandchildren compared to this widget.
+ 
+ @vindex address@hidden keyword}
+ @item :extra-offset
+ An integer indicating how many extra spaces to add to the widget's
+ children compared to this widget.
+ 
+ @vindex address@hidden keyword}
+ @item :notify
+ A function called each time the widget or a nested widget is changed.
+ The function is called with two or three arguments.  The first argument
+ is the widget itself, the second argument is the widget that was
+ changed, and the third argument is the event leading to the change, if
+ any.
+ 
+ @vindex address@hidden keyword}
+ @item :menu-tag
+ Tag used in the menu when the widget is used as an option in a
+ @code{menu-choice} widget.
+ 
+ @vindex address@hidden keyword}
+ @item :menu-tag-get
+ Function used for finding the tag when the widget is used as an option
+ in a @code{menu-choice} widget.  By default, the tag used will be either the
+ @code{:menu-tag} or @code{:tag} property if present, or the @code{princ}
+ representation of the @code{:value} property if not.
+ 
+ @vindex address@hidden keyword}
+ @item :match
+ Should be a function called with two arguments, the widget and a value,
+ and returning address@hidden if the widget can represent the specified value.
+ 
+ @vindex address@hidden keyword}
+ @item :validate
+ A function which takes a widget as an argument, and returns @code{nil}
+ if the widget's current value is valid for the widget.  Otherwise it
+ should return the widget containing the invalid data, and set that
+ widget's @code{:error} property to a string explaining the error.
+ 
+ The following predefined function can be used:
+ 
+ @defun widget-children-validate widget
+ All the @code{:children} of @var{widget} must be valid.
+ @end defun
+ 
+ @vindex address@hidden keyword}
+ @item :tab-order
+ Specify the order in which widgets are traversed with
+ @code{widget-forward} or @code{widget-backward}.  This is only partially
+ implemented.
+ 
+ @enumerate a
+ @item
+ Widgets with tabbing order @code{-1} are ignored.
+ 
+ @item
+ (Unimplemented) When on a widget with tabbing order @var{n}, go to the
+ next widget in the buffer with tabbing order @var{n+1} or @code{nil},
+ whichever comes first.
+ 
+ @item
+ When on a widget with no tabbing order specified, go to the next widget
+ in the buffer with a positive tabbing order, or @code{nil}
+ @end enumerate
+ 
+ @vindex address@hidden keyword}
+ @item :parent
+ The parent of a nested widget (e.g.@: a @code{menu-choice} item or an
+ element of a @code{editable-list} widget).
+ 
+ @vindex address@hidden keyword}
+ @item :sibling-args
+ This keyword is only used for members of a @code{radio-button-choice} or
+ @code{checklist}.  The value should be a list of extra keyword
+ arguments, which will be used when creating the @code{radio-button} or
+ @code{checkbox} associated with this item.
+ 
+ @end table
+ 
+ @deffn {User Option} widget-glyph-directory
+ Directory where glyphs are found.
+ Widget will look here for a file with the same name as specified for the
+ image, with either a @file{.xpm} (if supported) or @file{.xbm} extension.
+ @end deffn
+ 
+ @deffn{User Option} widget-glyph-enable
+ If address@hidden, allow glyphs to appear on displays where they are 
supported.
+ @end deffn
+ 
+ 
+ @menu
+ * link::
+ * url-link::
+ * info-link::
+ * push-button::
+ * editable-field::
+ * text::
+ * menu-choice::
+ * radio-button-choice::
+ * item::
+ * choice-item::
+ * toggle::
+ * checkbox::
+ * checklist::
+ * editable-list::
+ * group::
+ @end menu
+ 
+ @node link, url-link, Basic Types, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{link} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (link [KEYWORD ARGUMENT]...  [ VALUE ])
+ @end example
+ 
+ The @var{value}, if present, is used to initialize the @code{:value}
+ property.  The value should be a string, which will be inserted in the
+ buffer.
+ 
+ By default the link will be shown in brackets.
+ 
+ @defopt widget-link-prefix
+ String to prefix links.
+ @end defopt
+ 
+ @defopt widget-link-suffix
+ String to suffix links.
+ @end defopt
+ 
+ @node url-link, info-link, link, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{url-link} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (url-link [KEYWORD ARGUMENT]...  URL)
+ @end example
+ 
+ @findex address@hidden, and @code{url-link} widget}
+ When this link is invoked, the @acronym{WWW} browser specified by
+ @code{browse-url-browser-function} will be called with @var{url}.
+ 
+ @node info-link, push-button, url-link, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{info-link} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (info-link [KEYWORD ARGUMENT]...  ADDRESS)
+ @end example
+ 
+ When this link is invoked, the built-in Info reader is started on
+ @var{address}.
+ 
+ @node  push-button, editable-field, info-link, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{push-button} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (push-button [KEYWORD ARGUMENT]...  [ VALUE ])
+ @end example
+ 
+ The @var{value}, if present, is used to initialize the @code{:value}
+ property.  The value should be a string, which will be inserted in the
+ buffer.
+ 
+ By default the tag will be shown in brackets.
+ 
+ @defopt widget-push-button-prefix
+ String to prefix push buttons.
+ @end defopt
+ 
+ @defopt widget-push-button-suffix
+ String to suffix push buttons.
+ @end defopt
+ 
+ @node editable-field, text, push-button, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{editable-field} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (editable-field [KEYWORD ARGUMENT]... [ VALUE ])
+ @end example
+ 
+ The @var{value}, if present, is used to initialize the @code{:value}
+ property.  The value should be a string, which will be inserted in
+ field.  This widget will match all string values.
+ 
+ The following extra properties are recognized:
+ 
+ @table @code
+ @vindex address@hidden keyword}
+ @item :size
+ The width of the editable address@hidden
+ By default the field will reach to the end of the line.
+ 
+ @vindex address@hidden keyword}
+ @item :value-face
+ Face used for highlighting the editable field.  Default is
+ @code{widget-field-face}, see @ref{User Interface}.
+ 
+ @vindex address@hidden keyword}
+ @item :secret
+ Character used to display the value.  You can set this to e.g.@: @code{?*}
+ if the field contains a password or other secret information.  By
+ default, this is @code{nil}, and the value is not secret.
+ 
+ @vindex address@hidden keyword}
+ @item :valid-regexp
+ By default the @code{:validate} function will match the content of the
+ field with the value of this attribute.  The default value is @code{""}
+ which matches everything.
+ 
+ @vindex address@hidden keyword}
+ @vindex widget-field-keymap
+ @item :keymap
+ Keymap used in the editable field.  The default value is
+ @code{widget-field-keymap}, which allows you to use all the normal
+ editing commands, even if the buffer's major mode suppresses some of
+ them.  Pressing @key{RET} invokes the function specified by
+ @code{:action}.
+ @end table
+ 
+ @node text, menu-choice, editable-field, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{text} Widget
+ @findex address@hidden widget}
+ 
+ @vindex widget-text-keymap
+ This is just like @code{editable-field}, but intended for multiline text
+ fields.  The default @code{:keymap} is @code{widget-text-keymap}, which
+ does not rebind the @key{RET} key.
+ 
+ @node menu-choice, radio-button-choice, text, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{menu-choice} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (menu-choice [KEYWORD ARGUMENT]... TYPE ... )
+ @end example
+ 
+ The @var{type} argument represents each possible choice.  The widget's
+ value will be that of the chosen @var{type} argument.  This widget will
+ match any value matching at least one of the specified @var{type}
+ arguments.
+ 
+ @table @code
+ @vindex address@hidden keyword}
+ @item :void
+ Widget type used as a fallback when the value does not match any of the
+ specified @var{type} arguments.
+ 
+ @vindex address@hidden keyword}
+ @item :case-fold
+ Set this to @code{nil} if you don't want to ignore case when prompting for a
+ choice through the minibuffer.
+ 
+ @vindex address@hidden keyword}
+ @item :children
+ A list whose @sc{car} is the widget representing the currently chosen
+ type in the buffer.
+ 
+ @vindex address@hidden keyword}
+ @item :choice
+ The current chosen type.
+ 
+ @vindex address@hidden keyword}
+ @item :args
+ The list of types.
+ @end table
+ 
+ @node radio-button-choice, item, menu-choice, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{radio-button-choice} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (radio-button-choice [KEYWORD ARGUMENT]...  TYPE ... )
+ @end example
+ 
+ The @var{type} argument represents each possible choice.  The widget's
+ value will be that of the chosen @var{type} argument.  This widget will
+ match any value matching at least one of the specified @var{type}
+ arguments.
+ 
+ The following extra properties are recognized.
+ 
+ @table @code
+ @vindex address@hidden keyword}
+ @item :entry-format
+ This string will be inserted for each entry in the list.
+ The following @samp{%} escapes are available:
+ @table @samp
+ @item %v
+ Replace with the buffer representation of the @var{type} widget.
+ @item %b
+ Replace with the radio button.
+ @item %%
+ Insert a literal @samp{%}.
+ @end table
+ 
+ @vindex address@hidden keyword}
+ @item :button-args
+ A list of keywords to pass to the radio buttons.  Useful for setting
+ e.g.@: the @samp{:help-echo} for each button.
+ 
+ @vindex address@hidden keyword}
+ @item :buttons
+ The widgets representing the radio buttons.
+ 
+ @vindex address@hidden keyword}
+ @item :children
+ The widgets representing each type.
+ 
+ @vindex address@hidden keyword}
+ @item :choice
+ The current chosen type
+ 
+ @vindex address@hidden keyword}
+ @item :args
+ The list of types.
+ @end table
+ 
+ You can add extra radio button items to a @code{radio-button-choice}
+ widget after it has been created with the function
+ @code{widget-radio-add-item}.
+ 
+ @defun widget-radio-add-item widget type
+ Add to @code{radio-button-choice} widget @var{widget} a new radio button
+ item of type @var{type}.
+ @end defun
+ 
+ Please note that such items added after the @code{radio-button-choice}
+ widget has been created will @strong{not} be properly destructed when
+ you call @code{widget-delete}.
+ 
+ @node item, choice-item, radio-button-choice, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{item} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ ITEM ::= (item [KEYWORD ARGUMENT]... VALUE)
+ @end example
+ 
+ The @var{value}, if present, is used to initialize the @code{:value}
+ property.  The value should be a string, which will be inserted in the
+ buffer.  This widget will only match the specified value.
+ 
+ @node choice-item, toggle, item, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{choice-item} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ ITEM ::= (choice-item [KEYWORD ARGUMENT]... VALUE)
+ @end example
+ 
+ The @var{value}, if present, is used to initialize the @code{:value}
+ property.  The value should be a string, which will be inserted in the
+ buffer as a button.  Activating the button of a @code{choice-item} is
+ equivalent to activating the parent widget.  This widget will only match
+ the specified value.
+ 
+ @node toggle, checkbox, choice-item, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{toggle} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (toggle [KEYWORD ARGUMENT]...)
+ @end example
+ 
+ The widget has two possible states, @samp{on} and @samp{off}, which
+ correspond to a @code{t} or @code{nil} value, respectively.
+ 
+ The following extra properties are recognized:
+ 
+ @table @code
+ @item :on
+ A string representing the @samp{on} state.  By default the string
+ @samp{on}.
+ @item :off
+ A string representing the @samp{off} state.  By default the string
+ @samp{off}.
+ @vindex address@hidden keyword}
+ @item :on-glyph
+ Name of a glyph to be used instead of the @samp{:on} text string, on
+ emacsen that supports this.
+ @vindex address@hidden keyword}
+ @item :off-glyph
+ Name of a glyph to be used instead of the @samp{:off} text string, on
+ emacsen that supports this.
+ @end table
+ 
+ @node checkbox, checklist, toggle, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{checkbox} Widget
+ @findex address@hidden widget}
+ 
+ This widget has two possible states, @samp{selected} and
+ @samp{unselected}, which corresponds to a @code{t} or @code{nil} value.
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (checkbox [KEYWORD ARGUMENT]...)
+ @end example
+ 
+ @node checklist, editable-list, checkbox, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{checklist} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (checklist [KEYWORD ARGUMENT]...  TYPE ... )
+ @end example
+ 
+ The @var{type} arguments represent each checklist item.  The widget's
+ value will be a list containing the values of all checked @var{type}
+ arguments.  The checklist widget will match a list whose elements all
+ match at least one of the specified @var{type} arguments.
+ 
+ The following extra properties are recognized:
+ 
+ @table @code
+ @vindex address@hidden keyword}
+ @item :entry-format
+ This string will be inserted for each entry in the list.
+ The following @samp{%} escapes are available:
+ @table @samp
+ @item %v
+ Replaced with the buffer representation of the @var{type} widget.
+ @item %b
+ Replace with the checkbox.
+ @item %%
+ Insert a literal @samp{%}.
+ @end table
+ 
+ @vindex address@hidden keyword}
+ @item :greedy
+ Usually a checklist will only match if the items are in the exact
+ sequence given in the specification.  By setting @code{:greedy} to
+ address@hidden, it will allow the items to come in any sequence.
+ However, if you extract the value they will be in the sequence given
+ in the checklist, i.e.@: the original sequence is forgotten.
+ 
+ @vindex address@hidden keyword}
+ @item :button-args
+ A list of keywords to pass to the checkboxes.  Useful for setting
+ e.g.@: the @samp{:help-echo} for each checkbox.
+ 
+ @vindex address@hidden keyword}
+ @item :buttons
+ The widgets representing the checkboxes.
+ 
+ @vindex address@hidden keyword}
+ @item :children
+ The widgets representing each type.
+ 
+ @vindex address@hidden keyword}
+ @item :args
+ The list of types.
+ @end table
+ 
+ @node editable-list, group, checklist, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{editable-list} Widget
+ @findex address@hidden widget}
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (editable-list [KEYWORD ARGUMENT]... TYPE)
+ @end example
+ 
+ The value is a list, where each member represents one widget of type
+ @var{type}.
+ 
+ The following extra properties are recognized:
+ 
+ @table @code
+ @vindex address@hidden keyword}
+ @item :entry-format
+ This string will be inserted for each entry in the list.
+ The following @samp{%} escapes are available:
+ @table @samp
+ @item %v
+ This will be replaced with the buffer representation of the @var{type}
+ widget.
+ @item %i
+ Insert the @b{[INS]} button.
+ @item %d
+ Insert the @b{[DEL]} button.
+ @item %%
+ Insert a literal @samp{%}.
+ @end table
+ 
+ @vindex address@hidden keyword}
+ @item :insert-button-args
+ A list of keyword arguments to pass to the insert buttons.
+ 
+ @vindex address@hidden keyword}
+ @item :delete-button-args
+ A list of keyword arguments to pass to the delete buttons.
+ 
+ @vindex address@hidden keyword}
+ @item :append-button-args
+ A list of keyword arguments to pass to the trailing insert button.
+ 
+ @vindex address@hidden keyword}
+ @item :buttons
+ The widgets representing the insert and delete buttons.
+ 
+ @vindex address@hidden keyword}
+ @item :children
+ The widgets representing the elements of the list.
+ 
+ @vindex address@hidden keyword}
+ @item :args
+ List whose @sc{car} is the type of the list elements.
+ @end table
+ 
+ @node group,  , editable-list, Basic Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The @code{group} Widget
+ @findex address@hidden widget}
+ 
+ This widget simply group other widgets together.
+ 
+ Syntax:
+ 
+ @example
+ TYPE ::= (group [KEYWORD ARGUMENT]... TYPE...)
+ @end example
+ 
+ The value is a list, with one member for each @var{type}.
+ 
+ @node Sexp Types, Widget Properties, Basic Types, Top
+ @comment
+ @section Sexp Types
+ @cindex sexp types
+ 
+ A number of widgets for editing @dfn{s-expressions} (Lisp types), sexp
+ for short, are also available.  These basically fall in several
+ categories described in this section.
+ 
+ @menu
+ * constants::
+ * generic::
+ * atoms::
+ * composite::
+ @end menu
+ 
+ @node constants, generic, Sexp Types, Sexp Types
+ @comment  node-name,  next,  previous,  up
+ @subsection The Constant Widgets
+ @cindex constant widgets
+ 
+ The @code{const} widget can contain any Lisp expression, but the user is
+ prohibited from editing it, which is mainly useful as a component of one
+ of the composite widgets.
+ 
+ The syntax for the @code{const} widget is:
+ 
+ @example
+ TYPE ::= (const [KEYWORD ARGUMENT]...  [ VALUE ])
+ @end example
+ 
+ The @var{value}, if present, is used to initialize the @code{:value}
+ property and can be any s-expression.
+ 
+ @deffn Widget const
+ This will display any valid s-expression in an immutable part of the
+ buffer.
+ @end deffn
+ 
+ There are two variations of the @code{const} widget, namely
+ @code{variable-item} and @code{function-item}.  These should contain a
+ symbol with a variable or function binding.  The major difference from
+ the @code{const} widget is that they will allow the user to see the
+ variable or function documentation for the symbol.
+ 
+ @deffn Widget variable-item
+ An immutable symbol that is bound as a variable.
+ @end deffn
+ 
+ @deffn Widget function-item
+ An immutable symbol that is bound as a function.
+ @end deffn
+ 
+ @node generic, atoms, constants, Sexp Types
+ @comment  node-name,  next,  previous,  up
+ @subsection Generic Sexp Widget
+ @cindex generic sexp widget
+ 
+ The @code{sexp} widget can contain any Lisp expression, and allows the
+ user to edit it inline in the buffer.
+ 
+ The syntax for the @code{sexp} widget is:
+ 
+ @example
+ TYPE ::= (sexp [KEYWORD ARGUMENT]...  [ VALUE ])
+ @end example
+ 
+ @deffn Widget sexp
+ This will allow you to edit any valid s-expression in an editable buffer
+ field.
+ 
+ The @code{sexp} widget takes the same keyword arguments as the
+ @code{editable-field} widget.  @xref{editable-field}.
+ @end deffn
+ 
+ @node atoms, composite, generic, Sexp Types
+ @comment  node-name,  next,  previous,  up
+ @subsection Atomic Sexp Widgets
+ @cindex atomic sexp widget
+ 
+ The atoms are s-expressions that do not consist of other s-expressions.
+ For example, a string, a file name, or a symbol are atoms, while a list
+ is a composite type.  You can edit the value of an atom with the
+ following widgets.
+ 
+ The syntax for all the atoms are:
+ 
+ @example
+ TYPE ::= (NAME [KEYWORD ARGUMENT]...  [ VALUE ])
+ @end example
+ 
+ The @var{value}, if present, is used to initialize the @code{:value}
+ property and must be an expression of the same type as the widget.
+ That is, the string widget can only be initialized with a string.
+ 
+ All the atom widgets take the same keyword arguments as the
+ @code{editable-field} widget.  @xref{editable-field}.
+ 
+ @deffn Widget string
+ Allows you to edit a string in an editable field.
+ @end deffn
+ 
+ @deffn Widget regexp
+ Allows you to edit a regular expression in an editable field.
+ @end deffn
+ 
+ @deffn Widget character
+ Allows you to enter a character in an editable field.
+ @end deffn
+ 
+ @deffn Widget file
+ Allows you to edit a file name in an editable field.  If you invoke
+ the tag button, you can edit the file name in the mini-buffer with
+ completion.
+ 
+ Keywords:
+ @table @code
+ @vindex address@hidden keyword}
+ @item :must-match
+ If this is set to address@hidden, only existing file names will be
+ allowed in the minibuffer.
+ @end table
+ @end deffn
+ 
+ @deffn Widget directory
+ Allows you to edit a directory name in an editable field.
+ Similar to the @code{file} widget.
+ @end deffn
+ 
+ @deffn Widget symbol
+ Allows you to edit a Lisp symbol in an editable field.
+ @end deffn
+ 
+ @deffn Widget function
+ Allows you to edit a lambda expression, or a function name with completion.
+ @end deffn
+ 
+ @deffn Widget variable
+ Allows you to edit a variable name, with completion.
+ @end deffn
+ 
+ @deffn Widget integer
+ Allows you to edit an integer in an editable field.
+ @end deffn
+ 
+ @deffn Widget number
+ Allows you to edit a number in an editable field.
+ @end deffn
+ 
+ @deffn Widget boolean
+ Allows you to edit a boolean.  In Lisp this means a variable which is
+ either @code{nil} meaning false, or address@hidden meaning true.
+ @end deffn
+ 
+ 
+ @node composite,  , atoms, Sexp Types
+ @comment  node-name,  next,  previous,  up
+ @subsection Composite Sexp Widgets
+ @cindex composite sexp widgets
+ 
+ The syntax for the composite widget is:
+ 
+ @example
+ TYPE ::= (NAME [KEYWORD ARGUMENT]...  COMPONENT...)
+ @end example
+ 
+ @noindent
+ where each @var{component} must be a widget type.  Each component widget
+ will be displayed in the buffer, and will be editable by the user.
+ 
+ @deffn Widget cons
+ The value of a @code{cons} widget is a cons-cell where the @sc{car} is
+ the value of the first component and the @sc{cdr} is the value of the
+ second component.  There must be exactly two components.
+ @end deffn
+ 
+ @deffn Widget list
+ The value of a @code{list} widget is a list containing the value of
+ each of its component.
+ @end deffn
+ 
+ @deffn Widget vector
+ The value of a @code{vector} widget is a vector containing the value of
+ each of its component.
+ @end deffn
+ 
+ The above suffice for specifying fixed size lists and vectors.  To get
+ variable length lists and vectors, you can use a @code{choice},
+ @code{set}, or @code{repeat} widgets together with the @code{:inline}
+ keywords.  If any component of a composite widget has the @code{:inline}
+ keyword set, its value must be a list which will then be spliced into
+ the composite.  For example, to specify a list whose first element must
+ be a file name, and whose remaining arguments should either by the
+ symbol @code{t} or two files, you can use the following widget
+ specification:
+ 
+ @example
+ (list file
+       (choice (const t)
+               (list :inline t
+                     :value ("foo" "bar")
+                     string string)))
+ @end example
+ 
+ The value of a widget of this type will either have the form
+ @code{(file t)} or @code{(file string string)}.
+ 
+ This concept of inline is probably hard to understand.  It was certainly
+ hard to implement, so instead of confusing you more by trying to explain
+ it here, I'll just suggest you meditate over it for a while.
+ 
+ @deffn Widget choice
+ Allows you to edit a sexp which may have one of a fixed set of types.
+ It is currently implemented with the @code{choice-menu} basic widget,
+ and has a similar syntax.
+ @end deffn
+ 
+ @deffn Widget set
+ Allows you to specify a type which must be a list whose elements all
+ belong to given set.  The elements of the list are not significant.
+ This is implemented on top of the @code{checklist} basic widget, and has
+ a similar syntax.
+ @end deffn
+ 
+ @deffn Widget repeat
+ Allows you to specify a variable length list whose members are all of
+ the same type.  Implemented on top of the @code{editable-list} basic
+ widget, and has a similar syntax.
+ @end deffn
+ 
+ @node Widget Properties, Defining New Widgets, Sexp Types, Top
+ @comment  node-name,  next,  previous,  up
+ @section Properties
+ @cindex properties of widgets
+ @cindex widget properties
+ 
+ You can examine or set the value of a widget by using the widget object
+ that was returned by @code{widget-create}.
+ 
+ @defun widget-value widget
+ Return the current value contained in @var{widget}.
+ It is an error to call this function on an uninitialized widget.
+ @end defun
+ 
+ @defun widget-value-set widget value
+ Set the value contained in @var{widget} to @var{value}.
+ It is an error to call this function with an invalid @var{value}.
+ @end defun
+ 
+ @strong{Important:} You @emph{must} call @code{widget-setup} after
+ modifying the value of a widget before the user is allowed to edit the
+ widget again.  It is enough to call @code{widget-setup} once if you
+ modify multiple widgets.  This is currently only necessary if the widget
+ contains an editing field, but may be necessary for other widgets in the
+ future.
+ 
+ If your application needs to associate some information with the widget
+ objects, for example a reference to the item being edited, it can be
+ done with @code{widget-put} and @code{widget-get}.  The property names
+ must begin with a @samp{:}.
+ 
+ @defun widget-put widget property value
+ In @var{widget} set @var{property} to @var{value}.
+ @var{property} should be a symbol, while @var{value} can be anything.
+ @end defun
+ 
+ @defun widget-get widget property
+ In @var{widget} return the value for @var{property}.
+ @var{property} should be a symbol, the value is what was last set by
+ @code{widget-put} for @var{property}.
+ @end defun
+ 
+ @defun widget-member widget property
+ address@hidden if @var{widget} has a value (even @code{nil}) for
+ property @var{property}.
+ @end defun
+ 
+ Occasionally it can be useful to know which kind of widget you have,
+ i.e.@: the name of the widget type you gave when the widget was created.
+ 
+ @defun widget-type widget
+ Return the name of @var{widget}, a symbol.
+ @end defun
+ 
+ @cindex active widget
+ @cindex inactive widget
+ @cindex activate a widget
+ @cindex deactivate a widget
+ Widgets can be in two states: active, which means they are modifiable by
+ the user, or inactive, which means they cannot be modified by the user.
+ You can query or set the state with the following code:
+ 
+ @lisp
+ ;; Examine if @var{widget} is active or not.
+ (if (widget-apply @var{widget} :active)
+     (message "Widget is active.")
+   (message "Widget is inactive.")
+ 
+ ;; Make @var{widget} inactive.
+ (widget-apply @var{widget} :deactivate)
+ 
+ ;; Make @var{widget} active.
+ (widget-apply @var{widget} :activate)
+ @end lisp
+ 
+ A widget is inactive if it, or any of its ancestors (found by
+ following the @code{:parent} link), have been deactivated.  To make sure
+ a widget is really active, you must therefore activate both it and
+ all its ancestors.
+ 
+ @lisp
+ (while widget
+   (widget-apply widget :activate)
+   (setq widget (widget-get widget :parent)))
+ @end lisp
+ 
+ You can check if a widget has been made inactive by examining the value
+ of the @code{:inactive} keyword.  If this is address@hidden, the widget itself
+ has been deactivated.  This is different from using the @code{:active}
+ keyword, in that the latter tells you if the widget @strong{or} any of
+ its ancestors have been deactivated.  Do not attempt to set the
+ @code{:inactive} keyword directly.  Use the @code{:activate}
+ @code{:deactivate} keywords instead.
+ 
+ 
+ @node Defining New Widgets, Widget Browser, Widget Properties, Top
+ @comment  node-name,  next,  previous,  up
+ @section Defining New Widgets
+ @cindex new widgets
+ @cindex defining new widgets
+ 
+ You can define specialized widgets with @code{define-widget}.  It allows
+ you to create a shorthand for more complex widgets, including specifying
+ component widgets and new default values for the keyword
+ arguments.
+ 
+ @defun define-widget name class doc &rest args
+ Define a new widget type named @var{name} from @code{class}.
+ 
+ @var{name} and class should both be symbols, @code{class} should be one
+ of the existing widget types.
+ 
+ The third argument @var{doc} is a documentation string for the widget.
+ 
+ After the new widget has been defined, the following two calls will
+ create identical widgets:
+ 
+ @itemize @bullet
+ @item
+ @lisp
+ (widget-create @var{name})
+ @end lisp
+ 
+ @item
+ @lisp
+ (apply widget-create @var{class} @var{args})
+ @end lisp
+ @end itemize
+ 
+ @end defun
+ 
+ Using @code{define-widget} just stores the definition of the widget type
+ in the @code{widget-type} property of @var{name}, which is what
+ @code{widget-create} uses.
+ 
+ If you only want to specify defaults for keywords with no complex
+ conversions, you can use @code{identity} as your conversion function.
+ 
+ The following additional keyword arguments are useful when defining new
+ widgets:
+ @table @code
+ @vindex address@hidden keyword}
+ @item :convert-widget
+ Function to convert a widget type before creating a widget of that
+ type.  It takes a widget type as an argument, and returns the converted
+ widget type.  When a widget is created, this function is called for the
+ widget type and all the widget's parent types, most derived first.
+ 
+ The following predefined functions can be used here:
+ 
+ @defun widget-types-convert-widget widget
+ Convert @code{:args} as widget types in @var{widget}.
+ @end defun
+ 
+ @defun widget-value-convert-widget widget
+ Initialize @code{:value} from @code{:args} in @var{widget}.
+ @end defun
+ 
+ @vindex address@hidden keyword}
+ @item :copy
+ Function to deep copy a widget type.  It takes a shallow copy of the
+ widget type as an argument (made by @code{copy-sequence}), and returns a
+ deep copy.  The purpose of this is to avoid having different instances
+ of combined widgets share nested attributes.
+ 
+ The following predefined functions can be used here:
+ 
+ @defun widget-types-copy widget
+ Copy @code{:args} as widget types in @var{widget}.
+ @end defun
+ 
+ @vindex address@hidden keyword}
+ @item :value-to-internal
+ Function to convert the value to the internal format.  The function
+ takes two arguments, a widget and an external value, and returns the
+ internal value.  The function is called on the present @code{:value}
+ when the widget is created, and on any value set later with
+ @code{widget-value-set}.
+ 
+ @vindex address@hidden keyword}
+ @item :value-to-external
+ Function to convert the value to the external format.  The function
+ takes two arguments, a widget and an internal value, and returns the
+ external value.  The function is called on the present @code{:value}
+ when the widget is created, and on any value set later with
+ @code{widget-value-set}.
+ 
+ @vindex address@hidden keyword}
+ @item :create
+ Function to create a widget from scratch.  The function takes one
+ argument, a widget type, and creates a widget of that type, inserts it
+ in the buffer, and returns a widget object.
+ 
+ @vindex address@hidden keyword}
+ @item :delete
+ Function to delete a widget.  The function takes one argument, a widget,
+ and should remove all traces of the widget from the buffer.
+ 
+ The default value is:
+ 
+ @defun widget-default-delete widget
+ Remove @var{widget} from the buffer.
+ Delete all @code{:children} and @code{:buttons} in @var{widget}.
+ @end defun
+ 
+ In most cases you should not change this value, but instead use
+ @code{:value-delete} to make any additional cleanup.
+ 
+ @vindex address@hidden keyword}
+ @item :value-create
+ Function to expand the @samp{%v} escape in the format string.  It will
+ be called with the widget as its argument and should insert a
+ representation of the widget's value in the buffer.
+ 
+ Nested widgets should be listed in @code{:children} or @code{:buttons}
+ to make sure they are automatically deleted.
+ 
+ @vindex address@hidden keyword}
+ @item :value-delete
+ Should remove the representation of the widget's value from the buffer.
+ It will be called with the widget as its argument.  It doesn't have to
+ remove the text, but it should release markers and delete nested widgets
+ if these are not listed in @code{:children} or @code{:buttons}.
+ 
+ @vindex address@hidden keyword}
+ @item :value-get
+ Function to extract the value of a widget, as it is displayed in the
+ buffer.
+ 
+ The following predefined function can be used here:
+ 
+ @defun widget-value-value-get widget
+ Return the @code{:value} property of @var{widget}.
+ @end defun
+ 
+ @vindex address@hidden keyword}
+ @item :format-handler
+ Function to handle unknown @samp{%} escapes in the format string.  It
+ will be called with the widget and the character that follows the
+ @samp{%} as arguments.  You can set this to allow your widget to handle
+ non-standard escapes.
+ 
+ @findex widget-default-format-handler
+ You should end up calling @code{widget-default-format-handler} to handle
+ unknown escape sequences, which will handle the @samp{%h} and any future
+ escape sequences, as well as give an error for unknown escapes.
+ 
+ @vindex address@hidden keyword}
+ @item :action
+ Function to handle user initiated events.  By default, @code{:notify}
+ the parent.
+ 
+ The following predefined function can be used here:
+ 
+ @defun widget-parent-action widget &optional event
+ Tell @code{:parent} of @var{widget} to handle the @code{:action}.
+ Optional @var{event} is the event that triggered the action.
+ @end defun
+ 
+ @vindex address@hidden keyword}
+ @item :prompt-value
+ Function to prompt for a value in the minibuffer.  The function should
+ take four arguments, @var{widget}, @var{prompt}, @var{value}, and
+ @var{unbound} and should return a value for widget entered by the user.
+ @var{prompt} is the prompt to use.  @var{value} is the default value to
+ use, unless @var{unbound} is address@hidden, in which case there is no default
+ value.  The function should read the value using the method most natural
+ for this widget, and does not have to check that it matches.
+ @end table
+ 
+ If you want to define a new widget from scratch, use the @code{default}
+ widget as its base.
+ 
+ @deffn Widget default
+ Widget used as a base for other widgets.
+ 
+ It provides most of the functionality that is referred to as ``by
+ default'' in this text.
+ @end deffn
+ 
+ @node Widget Browser, Widget Minor Mode, Defining New Widgets, Top
+ @comment  node-name,  next,  previous,  up
+ @section Widget Browser
+ @cindex widget browser
+ 
+ There is a separate package to browse widgets.  This is intended to help
+ programmers who want to examine the content of a widget.  The browser
+ shows the value of each keyword, but uses links for certain keywords
+ such as @samp{:parent}, which avoids printing cyclic structures.
+ 
+ @deffn Command widget-browse @var{widget}
+ Create a widget browser for @var{widget}.
+ When called interactively, prompt for @var{widget}.
+ @end deffn
+ 
+ @deffn Command widget-browse-other-window @var{widget}
+ Create a widget browser for @var{widget} and show it in another window.
+ When called interactively, prompt for @var{widget}.
+ @end deffn
+ 
+ @deffn Command widget-browse-at @var{pos}
+ Create a widget browser for the widget at @var{pos}.
+ When called interactively, use the position of point.
+ @end deffn
+ 
+ @node  Widget Minor Mode, Utilities, Widget Browser, Top
+ @comment  node-name,  next,  previous,  up
+ @section Widget Minor Mode
+ @cindex widget minor mode
+ 
+ There is a minor mode for manipulating widgets in major modes that
+ don't provide any support for widgets themselves.  This is mostly
+ intended to be useful for programmers doing experiments.
+ 
+ @deffn Command widget-minor-mode
+ Toggle minor mode for traversing widgets.
+ With arg, turn widget mode on if and only if arg is positive.
+ @end deffn
+ 
+ @defvar widget-minor-mode-keymap
+ Keymap used in @code{widget-minor-mode}.
+ @end defvar
+ 
+ @node  Utilities, Widget Wishlist, Widget Minor Mode, Top
+ @comment  node-name,  next,  previous,  up
+ @section Utilities.
+ @cindex utility functions for widgets
+ 
+ @defun widget-prompt-value widget prompt [ value unbound ]
+ Prompt for a value matching @var{widget}, using @var{prompt}.
+ The current value is assumed to be @var{value}, unless @var{unbound} is
+ address@hidden@refill
+ @end defun
+ 
+ @defun widget-get-sibling widget
+ Get the item which @var{widget} is assumed to toggle.
+ This is only meaningful for radio buttons or checkboxes in a list.
+ @end defun
+ 
+ @node  Widget Wishlist,  Index, Utilities, Top
+ @comment  node-name,  next,  previous,  up
+ @section Wishlist
+ @cindex todo
+ 
+ @itemize @bullet
+ @item
+ It should be possible to add or remove items from a list with @kbd{C-k}
+ and @kbd{C-o} (suggested by @sc{rms}).
+ 
+ @item
+ The @samp{[INS]} and @samp{[DEL]} buttons should be replaced by a single
+ dash (@samp{-}).  The dash should be a button that, when invoked, asks
+ whether you want to add or delete an item (@sc{rms} wanted to git rid of
+ the ugly buttons, the dash is my idea).
+ 
+ @item
+ The @code{menu-choice} tag should be prettier, something like the abbreviated
+ menus in Open Look.
+ 
+ @item
+ Finish @code{:tab-order}.
+ 
+ @item
+ Make indentation work with glyphs and proportional fonts.
+ 
+ @item
+ Add commands to show overview of object and class hierarchies to the
+ browser.
+ 
+ @item
+ Find a way to disable mouse highlight for inactive widgets.
+ 
+ @item
+ Find a way to make glyphs look inactive.
+ 
+ @item
+ Add @code{property-list} widget.
+ 
+ @item
+ Add @code{association-list} widget.
+ 
+ @item
+ Add @code{key-binding} widget.
+ 
+ @item
+ Add @code{widget} widget for editing widget specifications.
+ 
+ @item
+ Find clean way to implement variable length list.
+ See @code{TeX-printer-list} for an explanation.
+ 
+ @item
+ @kbd{C-h} in @code{widget-prompt-value} should give type specific help.
+ 
+ @item
+ Add a @code{mailto} widget.
+ @end itemize
+ 
+ @node Index, , Widget Wishlist, Top
+ @comment  node-name,  next,  previous,  up
+ @unnumbered Index
+ 
+ This is an alphabetical listing of all concepts, functions, commands,
+ variables, and widgets described in this manual.
+ @printindex cp
+ 
+ @setchapternewpage odd
+ @contents
+ @bye
+ 
+ @ignore
+    arch-tag: 2b427731-4c61-4e72-85de-5ccec9c623f0
+ @end ignore