This chapter describes a number of features related to the display that Emacs presents to the user.
The function redraw-frame redisplays the entire
contents of a given frame (see section Frames).
Even more powerful is redraw-display:
Processing user input takes absolute priority over redisplay. If you call these functions when input is available, they do nothing immediately, but a full redisplay does happen eventually--after all the input has been processed.
Normally, suspending and resuming Emacs also refreshes the screen. Some terminal emulators record separate contents for display-oriented programs such as Emacs and for ordinary sequential display. If you are using such a terminal, you might want to inhibit the redisplay on resumption.
nil means there is
no need to redraw, nil means redrawing is needed. The
default is nil.
When a line of text extends beyond the right edge of a window, the line can either be continued on the next screen line, or truncated to one screen line. The additional screen lines used to display a long text line are called continuation lines. Normally, a `$' in the rightmost column of the window indicates truncation; a `\' on the rightmost column indicates a line that "wraps" onto the next line, which is also called continuing the line. (The display table can specify alternative indicators; see section Display Tables.)
Note that continuation is different from filling; continuation happens on the screen only, not in the buffer contents, and it breaks a line precisely at the right margin, not at a word boundary. See section Filling.
nil, which specifies
continuation. If the value is non-nil, then these
lines are truncated. If the variable truncate-partial-width-windows is
non-nil, then truncation is always used for
side-by-side windows (within one frame) regardless of the value of
truncate-lines.
truncate-lines, for buffers that do
not have buffer-local values for it.
nil, these lines are truncated; otherwise,
truncate-lines says what to do with them.
When horizontal scrolling (see section Horizontal Scrolling) is in use in a window, that forces truncation.
You can override the glyphs that indicate continuation or truncation using the display table; see section Display Tables.
If your buffer contains very long lines, and you use
continuation to display them, just thinking about them can make
Emacs redisplay slow. The column computation and indentation
functions also become slow. Then you might find it advisable to set
cache-long-line-scans to t.
nil, various indentation and motion functions, and
Emacs redisplay, cache the results of scanning the buffer, and
consult the cache to avoid rescanning regions of the buffer unless
they are modified. Turning on the cache slows down processing of short lines somewhat.
This variable is automatically buffer-local in every buffer.
The echo area is used for displaying messages made with
the message primitive, and for echoing keystrokes. It
is not the same as the minibuffer, despite the fact that the
minibuffer appears (when active) in the same place on the screen as
the echo area. The GNU Emacs Manual specifies the
rules for resolving conflicts between the echo area and the
minibuffer for use of that screen space (see section `The
Minibuffer' in The GNU Emacs Manual). Error messages
appear in the echo area; see section Errors.
You can write output in the echo area by using the Lisp printing
functions with t as the stream (see section Output Functions), or as follows:
printf control string. See
format in section Conversion of Characters and Strings,
for the details on the conversion specifications.
message returns the constructed string. In batch mode, message prints the message text on
the standard error stream, followed by a newline.
If string is nil, message
clears the echo area. If the minibuffer is active, this brings the
minibuffer contents back onto the screen immediately.
(message "Minibuffer depth is %d."
(minibuffer-depth))
-| Minibuffer depth is 0.
=> "Minibuffer depth is 0."
---------- Echo Area ----------
Minibuffer depth is 0.
---------- Echo Area ----------
message, but may display it in a dialog
box instead of the echo area. If this function is called in a
command that was invoked using the mouse--more precisely, if
last-nonmenu-event (see section Information from the Command Loop) is
either nil or a list--then it uses a dialog box or
pop-up menu to display the message. Otherwise, it uses the echo
area. (This is the same criterion that y-or-n-p uses
to make a similar decision; see section Yes-or-No Queries.) You can force use of the mouse or of the echo area by binding
last-nonmenu-event to a suitable value around the
call.
message, but uses a dialog box (or a
pop-up menu) whenever that is possible. If it is impossible to use
a dialog box or pop-up menu, because the terminal does not support
them, then message-box uses the echo area, like
message.
nil if there is
none.
nil, then the cursor appears at the
end of the message. Otherwise, the cursor appears at point--not in
the echo area at all. The value is normally nil; Lisp programs bind it to
t for brief periods of time.
(message nil) or for any other
reason.
Almost all the messages displayed in the echo area are also recorded in the `*Messages*' buffer.
t means there is no limit on how many lines to
keep. The value nil disables message logging entirely.
Here's how to display a message and prevent it from being logged:
(let (message-log-max) (message ...))
If the value is zero, then command input is not echoed.
You can make characters
invisible, so that they do not appear on the screen, with
the invisible property. This can be either a text
property (see section Text
Properties) or a property of an overlay (see section Overlays).
In the simplest case, any non-nil
invisible property makes a character invisible. This
is the default case--if you don't alter the default value of
buffer-invisibility-spec, this is how the
invisible property works.
More generally, you can use the variable
buffer-invisibility-spec to control which values of
the invisible property make text invisible. This
permits you to classify the text into different subsets in advance,
by giving them different invisible values, and
subsequently make various subsets visible or invisible by changing
the value of buffer-invisibility-spec.
Controlling visibility with
buffer-invisibility-spec is especially useful in a
program to display the list of entries in a data base. It permits
the implementation of convenient filtering commands to view just a
part of the entries in the data base. Setting this variable is very
fast, much faster than scanning all the text in the buffer looking
for properties to change.
invisible properties actually make a
character invisible. tinvisible property
is non-nil. This is the default.
invisible property fits
any one of these criteria, the character is invisible. The list can
have two kinds of elements:
atominvisible property
value is atom or if it is a list with atom as
a member.
(atom . t)invisible property
value is atom or if it is a list with atom as
a member. Moreover, if this character is at the end of a line and
is followed by a visible newline, it displays an ellipsis.
Two functions are specifically provided for adding elements to
buffer-invisibility-spec and removing elements from
it.
buffer-invisibility-spec (if it is not already present
in that list).
buffer-invisibility-spec.
One convention about the use of
buffer-invisibility-spec is that a major mode should
use the mode's own name as an element of
buffer-invisibility-spec and as the value of the
invisible property:
;; If you want to display an ellipsis:
(add-to-invisibility-spec '(my-symbol . t))
;; If you don't want ellipsis:
(add-to-invisibility-spec 'my-symbol)
(overlay-put (make-overlay beginning end)
'invisible 'my-symbol)
;; When done with the overlays:
(remove-from-invisibility-spec '(my-symbol . t))
;; Or respectively:
(remove-from-invisibility-spec 'my-symbol)
Ordinarily, commands that
operate on text or move point do not care whether the text is
invisible. The user-level line motion commands explicitly ignore
invisible newlines if line-move-ignore-invisible is
non-nil, but only because they are explicitly
programmed to do so.
Incremental search can make invisible overlays visible
temporarily and/or permanently when a match includes invisible
text. To enable this, the overlay should have a
non-nil isearch-open-invisible property.
The property value should be a function to be called with the
overlay as an argument. This function should make the overlay
visible permanently; it is used when the match overlaps the overlay
on exit from the search.
During the search, such overlays are made temporarily visible by
temporarily modifying their invisible and intangible properties. If
you want this to be done differently for a certain overlay, give it
an isearch-open-invisible-temporary property which is
a function. The function is called with two arguments: the first is
the overlay, and the second is t to make the overlay
visible, or nil to make it invisible again.
Selective display refers to a pair of related features for hiding certain lines on the screen.
The first variant, explicit selective display, is designed for use in a Lisp program: it controls which lines are hidden by altering the text. The invisible text feature (see section Invisible Text) has partially replaced this feature.
In the second variant, the choice of lines to hide is made automatically based on indentation. This variant is designed to be a user-level feature.
The way you control explicit selective display is by replacing a newline (control-j) with a carriage return (control-m). The text that was formerly a line following that newline is now invisible. Strictly speaking, it is temporarily no longer a line at all, since only newlines can separate lines; it is now part of the previous line.
Selective display does not directly affect editing commands. For
example, C-f (forward-char) moves point
unhesitatingly into invisible text. However, the replacement of
newline characters with carriage return characters affects some
editing commands. For example, next-line skips
invisible lines, since it searches only for newlines. Modes that
use selective display can also define commands that take account of
the newlines, or that make parts of the text visible or
invisible.
When you write a selectively displayed buffer into a file, all the control-m's are output as newlines. This means that when you next read in the file, it looks OK, with nothing invisible. The selective display effect is seen only within Emacs.
selective-display is
t, then any portion of a line that follows a control-m
is not displayed. This is explicit selective display.
selective-display is a positive
integer, then lines that start with more than that many columns of
indentation are not displayed.
When some portion of a buffer is invisible, the vertical
movement commands operate as if that portion did not exist,
allowing a single next-line command to skip any number
of invisible lines. However, character movement commands (such as
forward-char) do not skip the invisible portion, and
it is possible (if tricky) to insert or delete text in an invisible
portion.
In the examples below, we show the display appearance
of the buffer foo, which changes with the value of
selective-display. The contents of the buffer
do not change.
(setq selective-display nil)
=> nil
---------- Buffer: foo ----------
1 on this column
2on this column
3n this column
3n this column
2on this column
1 on this column
---------- Buffer: foo ----------
(setq selective-display 2)
=> 2
---------- Buffer: foo ----------
1 on this column
2on this column
2on this column
1 on this column
---------- Buffer: foo ----------
nil, then Emacs displays
`...' at the end of a line that is followed by
invisible text. This example is a continuation of the previous one.
(setq selective-display-ellipses t)
=> t
---------- Buffer: foo ----------
1 on this column
2on this column ...
2on this column
1 on this column
---------- Buffer: foo ----------
You can use a display table to substitute other text for the ellipsis (`...'). See section Display Tables.
The overlay arrow is useful for directing the user's attention to a particular line in a buffer. For example, in the modes used for interface to debuggers, the overlay arrow indicates the line of code about to be executed.
nil if the arrow feature is not in use.
The overlay string is displayed only in the buffer that this marker points into. Thus, only one buffer can have an overlay arrow at any given time.
You can do a similar job by creating an overlay with a
before-string property. See section Overlay Properties.
Temporary displays are used by Lisp programs to put output into a buffer and then present it to the user for perusal rather than for editing. Many help commands use this feature.
The string buffer-name specifies the temporary
buffer, which need not already exist. The argument must be a
string, not a buffer. The buffer is erased initially (with no
questions asked), and it is marked as unmodified after
with-output-to-temp-buffer exits.
with-output-to-temp-buffer binds
standard-output to the temporary buffer, then it
evaluates the forms in forms. Output using the Lisp
output functions within forms goes by default to that
buffer (but screen display and messages in the echo area, although
they are "output" in the general sense of the word, are not
affected). See section Output
Functions.
The value of the last form in forms is returned.
---------- Buffer: foo ----------
This is the contents of foo.
---------- Buffer: foo ----------
(with-output-to-temp-buffer "foo"
(print 20)
(print standard-output))
=> #<buffer foo>
---------- Buffer: foo ----------
20
#<buffer foo>
---------- Buffer: foo ----------
nil, with-output-to-temp-buffer calls
it as a function to do the job of displaying a help buffer. The
function gets one argument, which is the buffer it should display.
It is a good idea for this function to run
temp-buffer-show-hook just as
with-output-to-temp-buffer normally would, inside of
save-window-excursion and with the chosen window and
buffer selected.
with-output-to-temp-buffer after displaying the help
buffer. When the hook runs, the help buffer is current, and the
window it was displayed in is selected.
The momentary display remains until the next input event. If the
next input event is char,
momentary-string-display ignores it and returns.
Otherwise, that event remains buffered for subsequent use as input.
Thus, typing char will simply remove the string from the
display, while typing (say) C-f will remove the string
from the display and later (presumably) move point forward. The
argument char is a space by default.
The return value of momentary-string-display is not
meaningful.
If the string string does not contain control
characters, you can do the same job in a more general way by
creating (and then subsequently deleting) an overlay with a
before-string property. See section Overlay Properties.
If message is non-nil, it is displayed
in the echo area while string is displayed in the
buffer. If it is nil, a default message says to type
char to continue.
In this example, point is initially located at the beginning of the second line:
---------- Buffer: foo ---------- This is the contents of foo. -!-Second line. ---------- Buffer: foo ---------- (momentary-string-display "**** Important Message! ****" (point) ?\r "Type RET when done reading") => t ---------- Buffer: foo ---------- This is the contents of foo. **** Important Message! ****Second line. ---------- Buffer: foo ---------- ---------- Echo Area ---------- Type RET when done reading ---------- Echo Area ----------
You can use overlays to alter the appearance of a buffer's text on the screen, for the sake of presentation features. An overlay is an object that belongs to a particular buffer, and has a specified beginning and end. It also has properties that you can examine and set; these affect the display of the text within the overlay.
Overlay properties are like text properties in that the properties that alter how a character is displayed can come from either source. But in most respects they are different. Text properties are considered a part of the text; overlays are specifically considered not to be part of the text. Thus, copying text between various buffers and strings preserves text properties, but does not try to preserve overlays. Changing a buffer's text properties marks the buffer as modified, while moving an overlay or changing its properties does not. Unlike text property changes, overlay changes are not recorded in the buffer's undo list. See section Text Properties, for comparison.
prioritypriority value is larger takes priority over the
other, and its face attributes override the face attributes of the
lower priority overlay. Currently, all overlays take priority over
text properties. Please avoid using negative priority values, as we
have not yet decided just what they should mean.
windowwindow
property is non-nil, then the overlay applies only on
that window.
categorycategory property, we call it the category of
the overlay. It should be a symbol. The properties of the symbol
serve as defaults for the properties of the overlay.
face(foreground-color . color-name) or
(background-color . color-name). These
elements specify just the foreground color or just the background
color; therefore, there is no need to create a face for each color
that you want to use.
mouse-faceface when the mouse is within the range of
the overlay.
modification-hooksnil, and the
beginning and end of the text range to be modified. When called
after a change, each function receives five arguments: the overlay,
t, the beginning and end of the text range just
modified, and the length of the pre-change text replaced by that
range. (For an insertion, the pre-change length is zero; for a
deletion, that length is the number of characters deleted, and the
post-change beginning and end are equal.)
insert-in-front-hooksmodification-hooks functions.
insert-behind-hooksmodification-hooks functions.
invisibleinvisible
property can make the text in the overlay invisible, which means
that it does not appear on the screen. See section Invisible Text, for details.
intangibleintangible
property on an overlay works just like the intangible
text property. See section Properties
with Special Meanings, for details.
isearch-open-invisibleisearch-open-invisible-temporarybefore-stringafter-stringevaporatenil, the overlay is deleted automatically if it
ever becomes empty (i.e., if it spans no characters).
local-mapnil, it
specifies a keymap for a portion of the text. The property's value
replaces the buffer's local map, when the character after point is
within the overlay. See section Active
Keymaps.
These are the functions for reading and writing the properties of an overlay.
category property which
is a symbol, that symbol's prop property is used.
Otherwise, the value is nil.
See also the function get-char-property which
checks both overlay properties and text properties for a given
character. See section Examining Text
Properties.
This section describes the functions to create, delete and move overlays, and to examine their contents.
The arguments front-advance and rear-advance specify the insertion type for the start of the overlay and for the end of the overlay. See section Marker Insertion Types.
A deleted overlay is not permanently useless. You can give it a
new buffer position by calling move-overlay.
The return value is overlay.
This is the only valid way to change the endpoints of an overlay. Do not try modifying the markers in the overlay by hand, as that fails to update other vital data structures and can cause some overlays to be "lost".
Since not all characters have the same width, these functions let you check the width of a character. See section Indentation Primitives, and section Motion by Screen Lines, for related functions.
If string does not reach width, then the result ends where string ends. If one multi-column character in string extends across the column width, that character is not included in the result. Thus, the result can fall short of width but cannot go beyond it.
The optional argument start-column specifies the
starting column. If this is non-nil, then the first
start-column columns of the string are omitted from the
value. If one multi-column character in string extends
across the column start-column, that character is not
included.
The optional argument padding, if
non-nil, is a padding character added at the beginning
and end of the result string, to extend it to exactly
width columns. The padding character is used at the end
of the result if it falls short of width. It is also
used at the beginning of the result if one multi-column character
in string extends across the column
start-column.
(truncate-string-to-width "\tab\t" 12 4)
=> "ab"
(truncate-string-to-width "\tab\t" 12 4 ?\ )
=> " ab "
A face is a named collection of graphical attributes: font, foreground color, background color, and optional underlining. Faces control the display of text on the screen.
Each face has its own face number, which distinguishes faces at low levels within Emacs. However, for most purposes, you can refer to faces in Lisp programs by their names.
t if object is a face name symbol (or if it
is a vector of the kind used internally to record face data). It
returns nil otherwise.
Each face name is meaningful for all frames, and by default it has the same meaning in all frames. But you can arrange to give a particular face name a special meaning in one frame if you wish.
This table lists all the standard faces and their uses.
defaultmodelineregionsecondary-selectionhighlightunderlinebolditalicbold-italicThe way to define a new face is with defface. This
creates a kind of customization item (see section Writing Customization Definitions)
which the user can customize using the Customization buffer (see
section `Easy Customization' in The GNU Emacs
Manual).
When defface executes, it defines the face
according to spec, then uses any customizations that
were read from the `.emacs' file to override that
specification.
The purpose of spec is to specify how the face should
appear on different kinds of terminals. It should be an alist whose
elements have the form (display
atts). The element's CAR, display,
specifies a class of terminals. The CDR, atts, is a list
of face attributes and their values; it specifies what the face
should look like on that kind of terminal. The possible attributes
are defined in the value of
custom-face-attributes.
The display part of an element of spec determines which frames the element applies to. If more than one element of spec matches a given frame, the first matching element is the only one used for that frame. There are two possibilities for display:
tt is used in the last (or only) element of
spec.
(characteristic value...).
Here characteristic specifies a way of classifying
frames, and the values are possible classifications
which display should apply to. Here are the possible
values of characteristic:
typex, pc (for the MS-DOS console),
w32 (for MS Windows 9X/NT), or tty.
classcolor, grayscale, or
mono.
backgroundlight or
dark.
Here's how the standard face region could be
defined with defface:
(defface region
((((class color) (background dark))
(:background "blue"))
(t (:background "gray")))
"Used for displaying the region.")
Internally, defface uses the symbol property
face-defface-spec to record the face attributes
specified in defface, saved-face for the
attributes saved by the user with the customization buffer, and
face-documentation for the documentation string.
nil, specifies the background type to use for
interpreting face definitions. If it is dark, then
Emacs treats all frames as if they had a dark background,
regardless of their actual background colors. If it is
light, then Emacs treats all frames as if they had a
light background.
Here are all the ways to specify which face to use for display of text:
face
property; if so, it is displayed with that face. See section Properties with Special Meanings. If
the character has a mouse-face property, that is used
instead of the face property when the mouse is "near
enough" to the character.
face and
mouse-face properties too; they apply to all the text
covered by the overlay.
region-face, below).
If these various sources together specify more than one face for a particular character, Emacs merges the attributes of the various faces specified. The attributes of the faces of special glyphs come first; then comes the face for region highlighting, if appropriate; then come attributes of faces from overlays, followed by those from text properties, and last the default face.
When multiple overlays cover one character, an overlay with higher priority overrides those with lower priority. See section Overlays.
If an attribute such as the font or a color is not specified in any of the above ways, the frame's own font or color is used.
The attributes a face can specify include the font, the
foreground color, the background color, and underlining. The face
can also leave these unspecified by giving the value
nil for them.
Here are the primitives for creating and changing faces.
nil. It does nothing if there is already a face named
name.
If the optional argument frame is given, this function applies only to that frame. Otherwise it applies to each frame individually, copying attributes from old-face in each frame to new-face in the same frame.
If the optional argument new-frame is given, then
copy-face copies the attributes of old-face
in frame to new-name in
new-frame.
You can modify the attributes of an existing face with the following functions. If you specify frame, they affect just that frame; otherwise, they affect all frames as well as the defaults that apply to new frames.
Certain shades of gray are implemented by stipple patterns on black-and-white screens.
nil meaning don't use stipple. Normally there is no need to pay attention to stipple patterns, because they are used automatically to handle certain shades of gray.
nil means bold; nil
means non-bold.
nil means italic;
nil means non-italic.
nil
means do underline; nil means don't.
These functions examine the attributes of a face. If you don't specify frame, they refer to the default data for new frames.
nil if it doesn't have one.
nil if none was specified
for it.
t
if the faces face1 and face2 have the same
attributes for display.
t
if the face face displays differently from the default
face. A face is considered to be "the same" as the normal face if
each attribute is either the same as that of the default face or
nil (meaning to inherit from the default).
Normally, the value is the face number of the face named
region.
This section describes the mechanism by which Emacs shows a matching open parenthesis when the user inserts a close parenthesis.
blink-paren-function may be nil, in which
case nothing is done.
nil, then blink-matching-open does
nothing.
blink-paren-function. It assumes that
point follows a character with close parenthesis syntax and moves
the cursor momentarily to the matching opening character. If that
character is not already on the screen, it displays the character's
context in the echo area. To avoid long delays, this function does
not search farther than blink-matching-paren-distance
characters. Here is an example of calling this function explicitly.
(defun interactive-blink-matching-open ()
"Indicate momentarily the start of sexp before point."
(interactive)
(let ((blink-matching-paren-distance
(buffer-size))
(blink-matching-paren t))
(blink-matching-open)))
nil
means yes, nil means no. The default is
nil.
nil,
then mode lines are displayed in inverse video. Otherwise, mode
lines are displayed normally, just like text. The default is
t. For window frames, this displays mode lines using the face named
modeline, which is normally the inverse of the default
face unless you change it.
The usual display conventions define how to display each character code. You can override these conventions by setting up a display table (see section Display Tables). Here are the usual display conventions:
tab-width.
ctl-arrow. If it is non-nil, these codes
map to sequences of two glyphs, where the first glyph is the ASCII
code for `^'. (A display table can specify a glyph to
use instead of `^'.) Otherwise, these codes map just
like the codes in the range 128 to 255.
The usual display conventions apply even when there is a display
table, for any character whose entry in the active display table is
nil. Thus, when you set up a display table, you need
only specify the characters for which you want special
behavior.
These variables affect the way certain characters are displayed
on the screen. Since they change the number of columns the
characters occupy, they also affect the indentation functions.
These variables also affect how the mode line is displayed; if you
want to force redisplay of the mode line using the new values, call
the function force-mode-line-update (see section Mode Line Format).
nil, they are
displayed as a caret followed by the character: `^A'.
If it is nil, they are displayed as a backslash
followed by three octal digits: `\001'.
ctl-arrow in buffers that do
not override it. See section The
Default Value of a Buffer-Local Variable.
tab-to-tab-stop. See section Adjustable "Tab Stops".
You can use the display table feature to control how all possible character codes display on the screen. This is useful for displaying European languages that have letters not in the ASCII character set.
The display table maps each character code into a sequence of glyphs, each glyph being an image that takes up one character position on the screen. You can also define how to display each glyph on your terminal, using the glyph table.
Display tables affect how the mode line is displayed; if you
want to force redisplay of the mode line using a new display table,
call force-mode-line-update (see section Mode Line Format).
A display table is actually a char-table (see section Char-Tables) with
display-table as its subtype.
nil in all
elements.
The ordinary elements of the display table are indexed by
character codes; the element at index c says how to
display the character code c. The value should be
nil or a vector of glyph values (see section Glyphs). If an element is
nil, it says to display that character according to
the usual display conventions (see section Usual Display Conventions).
If you use the display table to change the display of newline characters, the whole buffer will be displayed as one long "line."
The display table also has six "extra slots" which serve special
purposes. Here is a table of their meanings; nil in
any slot means to use the default for that slot, as stated
below.
For example, here is how to construct a display table that
mimics the effect of setting ctl-arrow to a
non-nil value:
(setq disptab (make-display-table))
(let ((i 0))
(while (< i 32)
(or (= i ?\t) (= i ?\n)
(aset disptab i (vector ?^ (+ i 64))))
(setq i (1+ i)))
(aset disptab 127 (vector ?^ ??)))
truncation,
wrap, escape, control,
selective-display, and
vertical-border.
truncation,
wrap, escape, control,
selective-display, and
vertical-border.
Each window can specify a display table, and so can each buffer. When a buffer b is displayed in window w, display uses the display table for window w if it has one; otherwise, the display table for buffer b if it has one; otherwise, the standard display table if any. The display table chosen is called the active display table.
nil if
window does not have an assigned display table.
nil.
nil, that means the buffer does not have an
assigned display table.
nil by default.
If there is no display table to use for a particular
window--that is, if the window specifies none, its buffer specifies
none, and standard-display-table is
nil---then Emacs uses the usual display conventions
for all character codes in that window. See section Usual Display Conventions.
A glyph is a generalization of a character; it stands for an image that takes up a single character position on the screen. Glyphs are represented in Lisp as integers, just as characters are.
The meaning of each integer,
as a glyph, is defined by the glyph table, which is the value of
the variable glyph-table.
nil instead of a vector, then all glyphs are
simple (see below).
Here are the possible types of elements in the glyph table:
nilIf a glyph code is greater than or equal to the length of the glyph table, that code is automatically simple.
This section describes how to make Emacs ring the bell (or blink the screen) to attract the user's attention. Be conservative about how often you do this; frequent bells can become irritating. Also be careful not to use just beeping when signaling an error is more appropriate. (See section Errors.)
visible-bell below). It also terminates any keyboard
macro currently executing unless do-not-terminate is
non-nil.
ding.
nil means yes, nil means no. This is
effective on a window system, and on a character-only terminal
provided the terminal's Termcap entry defines the visible bell
capability (`vb').
nil, it specifies
how Emacs should "ring the bell." Its value should be a function of
no arguments.
Emacs works with several window systems, most notably the X Window System. Both Emacs and X use the term "window", but use it differently. An Emacs frame is a single window as far as X is concerned; the individual Emacs windows are not known to X at all.
xpcw32nilterm-setup-hook. This hook is used for internal purposes: setting up communication with the window system, and creating the initial window. Users should not interfere with it.