* Faces:: A face defines a graphics style for text characters:
font, colors, etc.
* Fringes:: Controlling window fringes.
+* Fringe Bitmaps:: Customizing fringe bitmaps.
* Scroll Bars:: Controlling vertical scroll bars.
+* Pointer Shape:: Controlling the mouse pointer shape.
* Display Property:: Enabling special display features.
* Images:: Displaying images in Emacs buffers.
* Buttons:: Adding clickable buttons to Emacs buffers.
@defvar buffer-invisibility-spec
This variable specifies which kinds of @code{invisible} properties
-actually make a character invisible.
+actually make a character invisible. Setting this variable makes it
+buffer-local.
@table @asis
@item @code{t}
@item evaporate
@kindex evaporate @r{(overlay property)}
If this property is non-@code{nil}, the overlay is deleted automatically
-if it becomes empty (i.e., if its length becomes zero). However,
-if the overlay is @emph{already} empty, @code{evaporate} does not
-delete it.
+if it becomes empty (i.e., if its length becomes zero). If you give
+an empty overlay a non-@code{nil} @code{evaporate} property, that deletes
+it immediately.
@item local-map
@cindex keymap of character (and overlays)
@item fringe
@kindex fringe @r{(face name)}
-This face controls the colors of window fringes, the thin areas on
+This face controls the default colors of window fringes, the thin areas on
either side that are used to display continuation and truncation glyphs.
@item minibuffer-prompt
@end defun
@defun face-differs-from-default-p face &optional frame
-This returns @code{t} if the face @var{face} displays differently from
-the default face. A face is considered to be ``the same'' as the
-default face if each attribute is either the same as that of the default
-face, or unspecified (meaning to inherit from the default).
+This returns non-@code{nil} if the face @var{face} displays
+differently from the default face.
@end defun
@node Auto Faces
@defvar fringes-outside-margins
If the value is non-@code{nil}, the frames appear outside
-the display margins.
+the display margins.
@end defvar
@defvar left-fringe-width
@var{right-width} @var{frames-outside-margins})}.
@end defun
+@defvar overflow-newline-into-fringe
+This variable, if non-@code{nil}, specifies that lines which are
+exactly as wide as the window (not counting the final newline
+character) shall not be broken into two lines on the display (with
+just the newline on the second line). Instead, the newline now
+overflows into the right fringe, and the cursor will be displayed in
+the fringe when positioned on that newline.
+@end defvar
+
+@defvar indicate-buffer-boundaries
+This buffer-local variable controls how the buffer boundaries and
+window scrolling is indicated in the fringes.
+
+ The buffer boundaries, i.e. first and last line in the buffer, can be
+marked with angle bitmaps in the left or right fringe. This can be
+combined with up and down arrow bitmaps shown at the top and bottom of
+the left or right fringe if the window can be scrolled in either
+direction.
+
+ If the value is @code{left} or @code{right}, both angle and arrow
+bitmaps are displayed in the left or right fringe, respectively.
+Any other non-@code{nil} value causes the bitmap on the top line to be
+displayed in the left fringe, and the bitmap on the bottom line in the
+right fringe.
+
+ If value is a cons @code{(angles . arrows)}, the car specifies the
+position of the angle bitmaps, and the cdr specifies the position of
+the arrow bitmaps. For example, @code{(t . right)} places the top
+angle bitmap in left fringe, the bottom angle bitmap in right fringe,
+and both arrow bitmaps in right fringe. To show just the angle
+bitmaps in the left fringe, but no arrow bitmaps, use @code{(left . nil)}.
+@end defvar
+
+@defvar default-indicate-buffer-boundaries
+The value of this variable is the default value for
+@code{indicate-buffer-boundaries} in buffers that do not override it.
+@end defvar
+
+@node Fringe Bitmaps
+@section Fringe Bitmaps
+@cindex Fringe Bitmaps
+
+ The @dfn{fringe bitmaps} are tiny icons Emacs displays in the fringe
+on a window system to indicate truncated or continued lines, buffer
+boundaries, overlay arrow, etc. The fringe bitmaps are shared by all
+frames and windows.
+
+ You can redefine the built-in fringe bitmaps, and you can define new
+fringe bitmaps. Emacs can handle a maximum of 255 different fringe
+bitmaps.
+
+A fringe bitmap is identified by an opaque integer, but Lisp code
+should use the following names defined by @code{(require 'fringe)}:
+
+Truncation and continuation line bitmaps:
+@code{left-truncation-fringe-bitmap},
+@code{right-truncation-fringe-bitmap},
+@code{continued-line-fringe-bitmap},
+@code{continuation-line-fringe-bitmap}.
+
+Buffer indication bitmaps:
+@code{up-arrow-fringe-bitmap},
+@code{down-arrow-fringe-bitmap},
+@code{top-left-angle-fringe-bitmap},
+@code{top-right-angle-fringe-bitmap},
+@code{bottom-left-angle-fringe-bitmap},
+@code{bottom-right-angle-fringe-bitmap},
+@code{left-bracket-fringe-bitmap},
+@code{right-bracket-fringe-bitmap}.
+
+Empty line indication bitmap:
+@code{empty-line-fringe-bitmap}.
+
+Overlay arrow bitmap:
+@code{overlay-arrow-fringe-bitmap}.
+
+Bitmaps for displaying the cursor in right fringe:
+@code{filled-box-cursor-fringe-bitmap},
+@code{hollow-box-cursor-fringe-bitmap},
+@code{hollow-square-fringe-bitmap}, @code{bar-cursor-fringe-bitmap},
+@code{hbar-cursor-fringe-bitmap}.
+
+Fringe bitmap opaque value indicating that no fringe bitmap is present:
+@code{no-fringe-bitmap}.
+
+Fringe bitmap opaque value indicating a reference to an undefined bitmap:
+@code{undef-fringe-bitmap}.
+
+ To display an specific fringe bitmap on a line in an Emacs window,
+use it as a @code{left-fringe} or @code{right-fringe} specifier in the
+@code{display} property of some text that is displayed on that line
+(@pxref{Display Property}).
+
+@defun define-fringe-bitmap bits &optional height width align bitmap
+Define a new fringe bitmap, or change an existing bitmap.
+
+The argument @code{bits} is either a string or a vector of integers,
+where each element (typically) corresponds to one row of the bitmap,
+and each bit of an integer corresponds to one pixel of the bitmap.
+
+The optional argument @code{height} specifies the height of the bitmap.
+If @code{height} is @code{nil}, the length of @code{bits} is used.
+
+The optional argument @code{width} specifies the width of the bitmap;
+it must be an integer between 1 and 16, or @code{nil} which defaults
+to a width of 8 pixels.
+
+The optional argument @code{align} may be one of @code{top},
+@code{center}, or @code{bottom}, indicating the positioning of the
+bitmap relative to the rows where it is used; the default is to center
+the bitmap.
+
+The @code{align} argument may also be a list @code{(ALIGN PERIODIC)}
+where @code{ALIGN} is intepreted as described above, and if
+@code{PERIODIC} is non-@code{nil} it specifies that the @code{bits} should
+be repeated until a bitmap of the specified @code{height} is created.
+
+The optional argument @code{bitmap} specifies the opaque integer that
+identifies an existing bitmap to redefine.
+
+The return value is a new opaque integer identifying the new bitmap number,
+or @code{nil} of there are no more free bitmap slots.
+@end defun
+
+@defun destroy-fringe-bitmap bitmap
+Destroy the fringe bitmap identified by the opaque integer
+@code{bitmap}. If @code{bitmap} identifies a standard fringe bitmap,
+the original built-in bitmap is restored.
+@end defun
+
+@defun set-fringe-bitmap-face bitmap &optional face
+Set face for a specific fringe bitmap @code{bitmap} to the face
+specified by the argument @code{face}.
+If @code{face} is @code{nil}, reset face to default @code{fringe} face.
+
+Normally, the specified face should be a face derived from the
+@code{fringe} face, only specifying the foreground color as the
+desired color of the fringe bitmap.
+@end defun
+
@node Scroll Bars
@section Scroll Bars
@code{set-window-scroll-bars} to specify what to do for a specific window:
@defun set-window-scroll-bars window width &optional vertical-type horizontal-type
-Set width and type of scroll bars of window @var{window}.
+Set width and type of scroll bars of window @var{window}.
If @var{window} is @code{nil}, the selected window is used.
@var{width} specifies the scroll bar width in pixels (@code{nil} means
use whatever is specified for width for the frame).
window take note of the new values by calling @code{set-window-buffer}
specifying the same buffer that is already displayed.
+@node Pointer Shape
+@section Pointer Shape
+
+Normally, the mouse pointer has the @code{text} shape over text and
+the @code{arrow} shape over window areas which do not correspond to
+any buffer text.
+
+The available pointer shapes are: @code{text} (or @code{nil}),
+@code{arrow}, @code{hand}, @code{vdrag}, @code{hdrag},
+@code{modeline}, and @code{hourglass}.
+
+The mouse pointer shape over text or images can be changed via the
+@code{pointer} text property, and for image with the @code{:pointer}
+and @code{:map} image properties.
+
+@defvar void-text-area-pointer
+@tindex void-text-area-pointer
+This variable specifies the mouse pointer shape in void text areas,
+i.e. the areas after the end of a line or below the last line in the
+buffer. The default is to use the @code{arrow} (non-text) pointer.
+@end defvar
+
@node Display Property
@section The @code{display} Property
@cindex display specification
@menu
* Specified Space:: Displaying one space with a specified width.
+* Pixel Specification:: Specifying space width or height in pixels.
* Other Display Specs:: Displaying an image; magnifying text; moving it
up or down on the page; adjusting the width
of spaces within text.
* Display Margins:: Displaying text or images to the side of the main text.
+* Display Fringe Bitmaps:: Displaying a fringe bitmap in a specific line.
* Conditional Display:: Making any of the above features conditional
depending on some Lisp expression.
@end menu
@table @code
@item :width @var{width}
-Specifies that the space width should be @var{width} times the normal
-character width. @var{width} can be an integer or floating point
-number.
+If @var{width} is an integer or floating point number, it specifies
+that the space width should be @var{width} times the normal character
+width. The @var{width} may also be a @dfn{pixel width} specification
+(@pxref{Pixel Specification}).
@item :relative-width @var{factor}
Specifies that the width of the stretch should be computed from the
character, multiplied by @var{factor}.
@item :align-to @var{hpos}
-Specifies that the space should be wide enough to reach @var{hpos}. The
-value @var{hpos} is measured in units of the normal character width. It
-may be an integer or a floating point number.
+Specifies that the space should be wide enough to reach @var{hpos}.
+If the value @var{hpos} is an integer or a floating point number, it
+is measured in units of the normal character width. The @var{hpos}
+may also be a @dfn{pixel width} specification (@pxref{Pixel Specification}).
@end table
+ The @code{:height} and @code{:align-to} properties are also supported
+on non-window systems.
+
You should use one and only one of the above properties. You can
also specify the height of the space, with other properties:
@table @code
@item :height @var{height}
-Specifies the height of the space, as @var{height},
-measured in terms of the normal line height.
+Specifies the height of the space.
+If @var{height} is an integer or floating point number, it specifies
+that the space height should be @var{height} times the normal character
+height. The @var{height} may also be a @dfn{pixel height} specification
+(@pxref{Pixel Specification}).
@item :relative-height @var{factor}
Specifies the height of the space, multiplying the ordinary height
of the text having this display specification by @var{factor}.
@item :ascent @var{ascent}
-Specifies that @var{ascent} percent of the height of the space should be
-considered as the ascent of the space---that is, the part above the
-baseline. The value of @var{ascent} must be a non-negative number no
-greater than 100.
+If the value of @var{ascent} is a non-negative number no greater than
+100, it specifies that @var{ascent} percent of the height of the space
+should be considered as the ascent of the space---that is, the part
+above the baseline. The ascent may also be specified in pixel units
+with a @dfn{pixel ascent} specification (@pxref{Pixel Specification}).
+
@end table
Don't use both @code{:height} and @code{:relative-height} together.
+@node Pixel Specification
+@subsection Pixel Specification for Spaces
+@cindex spaces, pixel specification
+
+ The value of the @code{:width}, @code{:align-to}, @code{:height},
+and @code{:ascent} properties can be a (trivial) expression
+which is evaluated during redisplay. The result of the evaluation is
+used as an absolute number of pixels.
+
+ The following expressions are supported:
+
+@example
+@group
+ EXPR ::= NUM | (NUM) | UNIT | ELEM | POS | IMAGE | FORM
+ NUM ::= INTEGER | FLOAT | SYMBOL
+ UNIT ::= in | mm | cm | width | height
+ ELEM ::= left-fringe | right-fringe | left-margin | right-margin
+ | scroll-bar | text
+ POS ::= left | center | right
+ FORM ::= (NUM . EXPR) | (OP EXPR ...)
+ OP ::= + | -
+@end group
+@end example
+
+ The form @var{NUM} specifies a fractional width or height of the
+default frame font size. The form @code{(@var{NUM})} specifies an
+absolute number of pixels. If a symbol @var{SYMBOL} is specified, its
+buffer-local variable binding is used.
+
+ The @code{in}, @code{mm}, and @code{cm} units specifies the number
+of pixels per inch, milli-meter, and centi-meter, resp. The
+@code{width} and @code{height} units correspond to the width and
+height of the current face font. An image specification @var{IMAGE}
+corresponds to the width or height of the image.
+
+ The @code{left-fringe}, @code{right-fringe}, @code{left-margin},
+@code{right-margin}, @code{scroll-bar}, and @code{text} elements
+specify to the width of the corresponding area of the window.
+
+ The @code{left}, @code{center}, and @code{right} positions can be
+used with @code{:align-to} to specify a position relative to the left
+edge, center, or right edge of the text area.
+
+ One of the above window elements (except @code{text}) can also be
+used with @code{:align-to} to specify that the position is relative to
+the left edge of the given area. Once the base offset for a relative
+position has been set (by the first occurrence of one of these
+symbols), further occurences of these symbols are interpreted as the
+width of the specified area. For example, to align to the center of
+the left-margin, use
+
+@example
+:align-to (+ left-margin (0.5 . left-margin))
+@end example
+
+ If no specific base offset is set for alignment, it is always relative
+to the left edge of the text area. For example, @samp{:align-to 0} in a
+header-line aligns with the first text column in the text area.
+
+ The value of the form @code{(@var{NUM} . @var{EXPR})} is the value of
+@var{NUM} multiplied by the value of the expression @var{EXPR}. For
+example, @samp{(2 . in)} specifies a width of 2 inches, while
+@samp{(0.5 . IMAGE)} specifies half the width (or height) of the
+specified image.
+
+ The form @code{(+ @var{EXPR} ...)} adds up the value of the
+expressions. The form @code{(- @var{EXPR} ...)} negates or subtracts
+the value of the expressions.
+
+
@node Other Display Specs
@subsection Other Display Specifications
display specification, it means to display the image instead of the text
that has the display specification.
+@item (slice @var{x} @var{y} @var{width} @var{height})
+This property is used with an @code{image} property to specify a
+@dfn{slice} (a partial area) of the image to display. The top left
+corner of the slice is specified by @var{y} and @var{x} and the width
+and height of the slice is specified by @var{width} and @var{height}.
+Integer values are taken as pixel values. A floating point number in
+the range 0.0 - 1.0 is relative to the width or height of the whole
+image.
+
@item ((margin nil) @var{string})
@itemx @var{string}
A display specification of this form means to display @var{string}
If @var{window} is @code{nil}, the selected window is used.
@end defun
+@node Display Fringe Bitmaps
+@subsection Displaying Bitmaps in the Fringes
+@cindex display fringes
+@cindex margins, fringes
+
+ You can display a bitmap in the left or right fringes for a given
+line in a window using the @code{display} property.
+
+ To put text in the left or right fringe of the window, use a
+display specification of the form @code{(left-fringe @var{bitmap} [@var{face}])}
+or @code{(right-fringe @var{bitmap} [@var{face}])} on one of the
+characters on the corresponding text line.
+
+ The @var{bitmap} is an opaque integer identifying the bitmap, and the
+optional @var{face} is the name of the face whose foreground and
+background color is to be used for displaying the bitmap.
+
+@defun fringe-bitmaps-at-pos &optional pos window
+This function returns the fringe bitmaps of the display row containing
+position @var{pos} in window @var{window}. The return value is a cons
+@code{(@var{left} . @var{right})} where @var{left} and @var{right}
+are the fringe bitmap numbers for the bitmaps in the left and right
+fringe, resp.
+
+ Returns @code{nil} if @var{pos} is not visible in window
+@var{window}. If @var{window} is @code{nil}, use the selected window.
+If @var{pos} is @code{nil}, use value of point in that window.
+@end defun
+
@node Conditional Display
@subsection Conditional Display Specifications
@cindex conditional display specifications
@code{display} property, this feature is available starting in Emacs 21.
Emacs can display a number of different image formats; some of them
-are supported only if particular support libraries are installed on your
-machine. The supported image formats include XBM, XPM (needing the
+are supported only if particular support libraries are installed on
+your machine. In some environments, Emacs allows loading image
+libraries on demand; if so, the variable @code{image-library-alist}
+can be used to modify the set of known names for these dynamic
+libraries (though it is not posible to add new image formats).
+
+ The supported image formats include XBM, XPM (needing the
libraries @code{libXpm} version 3.4k and @code{libz}), GIF (needing
@code{libungif} 4.1.0), Postscript, PBM, JPEG (needing the
@code{libjpeg} library version v6a), TIFF (needing @code{libtiff} v3.4),
@defvar image-types
This variable contains a list of those image type symbols that are
-supported in the current configuration.
+potentially supported in the current configuration.
+@emph{Potentially} here means that Emacs knows about the image types,
+not necessarily that they can be loaded (they could depend on
+unavailable dynamic libraries, for example).
+
+To know which image types are really available, use
+@code{image-type-available-p}.
+@end defvar
+
+@defvar image-library-alist
+This in an alist of image types vs external libraries needed to
+display them.
+
+Each element is a list @code{(@var{image-type} @var{library}...)},
+where the car is a supported image format from @code{image-types}, and
+the rest are strings giving alternate filenames for the corresponding
+external libraries to load.
+
+Emacs tries to load the libraries in the order they appear on the
+list; if none is loaded, the running session of Emacs won't support
+the image type. @code{pbm} and @code{xbm} don't need to be listed;
+they're always supported.
+
+This variable is ignored if the image libraries are statically linked
+into Emacs.
@end defvar
+@defun image-type-available-p type
+@findex image-type-available-p
+
+This function returns non-@code{nil} if image type @var{type} is
+available, i.e., if images of this type can be loaded and displayed in
+Emacs. @var{type} should be one of the types contained in
+@code{image-types}.
+
+For image types whose support libraries are statically linked, this
+function always returns @code{t}; for other image types, it returns
+@code{t} if the dynamic library could be loaded, @code{nil} otherwise.
+@end defun
+
@menu
* Image Descriptors:: How to specify an image for use in @code{:display}.
* XBM Images:: Special features for XBM format.
If @var{mask} is @code{nil}, remove a mask from the image, if it has
one. Images in some formats include a mask which can be removed by
specifying @code{:mask nil}.
+
+@item :pointer @var{shape}
+This specifies the pointer shape when the mouse pointer is over this
+image. @xref{Pointer Shapes}, for available pointer shapes.
+
+@item :map @var{map}
+This associates an image map of @dfn{hot spots} with this image.
+
+An image map is an alist where each element has the format
+@code{(@var{area} @var{id} @var{plist})}. An @var{area} is specified
+as either a rectangle, a circle, or a polygon.
+
+A rectangle is a cons
+@code{(rect . ((@var{x0} . @var{y0}) . (@var{x1} . @var{y1})))}
+which specifies the pixel coordinates of the upper left and bottom right
+corners of the rectangle area.
+
+A circle is a cons
+@code{(circle . ((@var{x0} . @var{y0}) . @var{r}))}
+which specifies the center and the radius of the circle; @var{r} may
+be a float or integer.
+
+A polygon is a cons
+@code{(poly . [@var{x0} @var{y0} @var{x1} @var{y1} ...])}
+where each pair in the vector describes one corner in the polygon.
+
+When the mouse pointer is above a hot-spot area of an image, the
+@var{plist} of that hot-spot is consulted; if it contains a @code{help-echo}
+property it defines a tool-tip for the hot-spot, and if it contains
+a @code{pointer} property, it defines the shape of the mouse cursor when
+it is over the hot-spot.
+@xref{Pointer Shapes}, for available pointer shapes.
+
+When you click the mouse when the mouse pointer is over a hot-spot, an
+event is composed by combining the @var{id} of the hot-spot with the
+mouse event, e.g. @samp{[area4 mouse-1]} if the hot-spot's @var{id} is
+@samp{area4}.
+
@end table
@defun image-mask-p spec &optional frame
For GIF images, specify image type @code{gif}. Because of the patents
in the US covering the LZW algorithm, the continued use of GIF format is
a problem for the whole Internet; to end this problem, it is a good idea
-for everyone, even outside the US, to stop using GIFS right away
+for everyone, even outside the US, to stop using GIFs right away
(@uref{http://www.burnallgifs.org/}). But if you still want to use
them, Emacs can display them.
property yourself, but it is easier to use the functions in this
section.
-@defun insert-image image &optional string area
+@defun insert-image image &optional string area slice
This function inserts @var{image} in the current buffer at point. The
value @var{image} should be an image descriptor; it could be a value
returned by @code{create-image}, or the value of a symbol defined with
@code{nil} or omitted, the image is displayed at point within the
buffer's text.
+The argument @var{slice} specifies a slice of the image to insert. If
+@var{slice} is @code{nil} or omitted the whole image is inserted.
+Otherwise, @var{slice} is a list
+@code{(@var{x} @var{y} @var{width} @var{height})}
+which specifies the @var{x} and @var{y} positions and
+@var{width} and @var{height} of the image area to insert. Integer
+values are taken as pixel values. A floating point number in the
+range 0.0 - 1.0 is relative to the width or height of the image.
+
Internally, this function inserts @var{string} in the buffer, and gives
it a @code{display} property which specifies @var{image}. @xref{Display
Property}.
@end defun
+@defun insert-sliced-image image &optional string area rows cols
+This function inserts @var{image} in the current buffer at point like
+@code{insert-image}, but the image is automatically split into
+@var{rows} x @var{cols} equally sized slices.
+@end defun
+
@defun put-image image pos &optional string area
This function puts image @var{image} in front of @var{pos} in the
current buffer. The argument @var{pos} should be an integer or a
etc. Emacs uses buttons for the hyper-links in help text and the like.
A button is essentially a set of properties attached (via text
-properties or overlays) to a region of text in an emacs buffer, which
+properties or overlays) to a region of text in an Emacs buffer, which
are called its button properties. @xref{Button Properties}.
One of the these properties (@code{action}) is a function, which will
The invoked function may then examine the button and use its other
properties as desired.
-In some ways the emacs button package duplicates functionality offered
+In some ways the Emacs button package duplicates functionality offered
by the widget package (@pxref{Top, , Introduction, widget, The Emacs
Widget Library}), but the button package has the advantage that it is
much faster, much smaller, and much simpler to use (for elisp
@menu
* Button Properties:: Button properties with special meanings.
* Button Types:: Defining common properties for classes of buttons.
-* Making Buttons:: Adding buttons to emacs buffers.
+* Making Buttons:: Adding buttons to Emacs buffers.
* Manipulating Buttons:: Getting and setting properties of buttons.
* Button Buffer Commands:: Buffer-wide commands and bindings for buttons.
-* Manipulating Button Types::
+* Manipulating Button Types::
@end menu
@node Button Properties
@item face
@kindex face @r{(button property)}
-This is an emacs face controlling how buttons of this type are
+This is an Emacs face controlling how buttons of this type are
displayed; by default this is the @code{button} face.
@item mouse-face
@kindex mouse-face @r{(button property)}
This is an additional face which controls appearance during
mouse-overs (merged with the usual button face); by default this is
-the usual emacs @code{highlight} face.
+the usual Emacs @code{highlight} face.
@item keymap
@kindex keymap @r{(button property)}
@item help-echo
@kindex help-index @r{(button property)}
-A string displayed by the emacs tool-tip help system; by default,
+A string displayed by the Emacs tool-tip help system; by default,
@code{"mouse-2, RET: Push this button"}.
@item button
Buttons are associated with a region of text, using an overlay or
text-properties to hold button-specific information, all of which are
initialized from the button's type (which defaults to the built-in
-button type @code{button}). Like all emacs text, the appearance of
+button type @code{button}). Like all Emacs text, the appearance of
the button is governed by the @code{face} property; by default (via
the @code{face} property inherited from the @code{button} button-type)
this is a simple underline, like a typical web-page link.
Insert a button with the label @var{label}.
@end defun
-The following functions are similar, but use emacs text-properties
+The following functions are similar, but use Emacs text-properties
(@pxref{Text Properties}) to hold the button properties, making the
button actually part of the text instead of being a property of the
buffer (using text-properties is usually faster than using overlays,
@cindex button buffer commands
These are commands and functions for locating and operating on
-buttons in an emacs buffer.
+buttons in an Emacs buffer.
@code{push-button} is the command that a user uses to actually `push'
a button, and is bound by default in the button itself to @key{RET}