1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997, 2000, 2001
3 @c Free Software Foundation, Inc.
4 @c See file emacs.texi for copying conditions.
5 @node Display, Search, Registers, Top
6 @chapter Controlling the Display
8 Since only part of a large buffer fits in the window, Emacs tries to
9 show a part that is likely to be interesting. Display-control commands
10 allow you to specify which part of the text you want to see, and how to
14 * Faces:: How to change the display style using faces.
15 * Font Lock:: Minor mode for syntactic highlighting using faces.
16 * Highlight Changes:: Using colors to show where you changed the buffer.
17 * Highlight Interactively:: Tell Emacs what text to highlight.
18 * Trailing Whitespace:: Showing possibly-spurious trailing whitespace.
19 * Scrolling:: Moving text up and down in a window.
20 * Horizontal Scrolling:: Moving text left and right in a window.
21 * Follow Mode:: Follow mode lets two windows scroll as one.
22 * Selective Display:: Hiding lines with lots of indentation.
23 * Optional Mode Line:: Optional mode line display features.
24 * Text Display:: How text characters are normally displayed.
25 * Display Custom:: Information on variables for customizing display.
26 * Cursor Display:: Features for displaying the cursor.
30 @section Using Multiple Typefaces
33 When using Emacs with a window system, you can set up multiple
34 styles of displaying characters. Each style is called a @dfn{face}.
35 Each face can specify various attributes, such as the height, weight
36 and slant of the characters, the foreground and background color, and
37 underlining. But it does not have to specify all of them.
39 Features which rely on text in multiple faces (such as Font Lock mode)
40 will also work on non-windowed terminals that can display more than one
41 face, whether by colors or underlining and emboldening. This includes
42 the console on GNU/Linux, an @code{xterm} which supports colors, the
43 MS-DOS display (@pxref{MS-DOS}), and the MS-Windows version invoked with
44 the @option{-nw} option. Emacs determines automatically whether the
45 terminal has this capability.
47 You control the appearance of a part of the text in the buffer by
48 specifying the face or faces to use for it. The style of display used
49 for any given character is determined by combining the attributes of
50 all the applicable faces specified for that character. Any attribute
51 that isn't specified by these faces is taken from the @code{default} face,
52 whose attributes reflect the default settings of the frame itself.
54 Enriched mode, the mode for editing formatted text, includes several
55 commands and menus for specifying faces for text in the buffer.
56 @xref{Format Faces}, for how to specify the font for text in the
57 buffer. @xref{Format Colors}, for how to specify the foreground and
60 @cindex face colors, setting
61 @findex set-face-foreground
62 @findex set-face-background
63 To alter the appearance of a face, use the customization buffer.
64 @xref{Face Customization}. You can also use X resources to specify
65 attributes of particular faces (@pxref{Resources X}). Alternatively,
66 you can change the foreground and background colors of a specific face
67 with @kbd{M-x set-face-foreground} and @kbd{M-x set-face-background}.
68 These commands prompt in the minibuffer for a face name and a color
69 name, with completion, and then set that face to use the specified
70 color. Changing the colors of the @code{default} face also changes
71 the foreground and background colors on all frames, both existing and
72 those to be created in the future. (You can also set foreground and
73 background colors for the current frame only; see @ref{Frame
76 Emacs 21 can correctly display variable-width fonts, but Emacs
77 commands that calculate width and indentation do not know how to
78 calculate variable widths. This can sometimes lead to incorrect
79 results when you use variable-width fonts. In particular, indentation
80 commands can give inconsistent results, so we recommend you avoid
81 variable-width fonts for editing program source code. Filling will
82 sometimes make lines too long or too short. We plan to address these
83 issues in future Emacs versions.
85 @findex list-faces-display
86 To see what faces are currently defined, and what they look like, type
87 @kbd{M-x list-faces-display}. It's possible for a given face to look
88 different in different frames; this command shows the appearance in the
89 frame in which you type it. Here's a list of the standard defined
94 This face is used for ordinary text that doesn't specify any other face.
96 This face is used for mode lines. By default, it's drawn with shadows
97 for a ``raised'' effect on window systems, and drawn as the inverse of
98 the default face on non-windowed terminals. @xref{Display Custom}.
100 Similar to @code{mode-line} for a window's header line. Most modes
101 don't use the header line, but the Info mode does.
103 This face is used for highlighting portions of text, in various modes.
104 For example, mouse-sensitive text is highlighted using this face.
106 This face is used for highlighting Isearch matches.
107 @item isearch-lazy-highlight-face
108 This face is used for lazy highlighting of Isearch matches other than
111 This face is used for displaying a selected region (when Transient Mark
112 mode is enabled---see below).
113 @item secondary-selection
114 This face is used for displaying a secondary X selection (@pxref{Secondary
117 This face uses a bold variant of the default font, if it has one.
119 This face uses an italic variant of the default font, if it has one.
121 This face uses a bold italic variant of the default font, if it has one.
123 This face underlines text.
125 The basic fixed-pitch face.
128 The face for the fringes to the left and right of windows on graphic
129 displays. (The fringes are the narrow portions of the Emacs frame
130 between the text area and the window's right and left borders.)
132 This face determines the visual appearance of the scroll bar.
134 This face determines the color of the frame border.
136 This face determines the color of the cursor.
138 This face determines the color of the mouse pointer.
140 This is the basic tool-bar face. No text appears in the tool bar, but the
141 colors of this face affect the appearance of tool bar icons.
143 This face is used for tooltips.
145 This face determines the colors and font of Emacs's menus. Setting the
146 font of LessTif/Motif menus is currently not supported; attempts to set
147 the font are ignored in this case.
148 @item trailing-whitespace
149 The face for highlighting trailing whitespace when
150 @code{show-trailing-whitespace} is non-nil; see @ref{Trailing Whitespace}.
152 The basic variable-pitch face.
155 @cindex @code{region} face
156 When Transient Mark mode is enabled, the text of the region is
157 highlighted when the mark is active. This uses the face named
158 @code{region}; you can control the style of highlighting by changing the
159 style of this face (@pxref{Face Customization}). @xref{Transient Mark},
160 for more information about Transient Mark mode and activation and
161 deactivation of the mark.
163 One easy way to use faces is to turn on Font Lock mode. This minor
164 mode, which is always local to a particular buffer, arranges to
165 choose faces according to the syntax of the text you are editing. It
166 can recognize comments and strings in most languages; in several
167 languages, it can also recognize and properly highlight various other
168 important constructs. @xref{Font Lock}, for more information about
169 Font Lock mode and syntactic highlighting.
171 You can print out the buffer with the highlighting that appears
172 on your screen using the command @code{ps-print-buffer-with-faces}.
176 @section Font Lock mode
177 @cindex Font Lock mode
178 @cindex mode, Font Lock
179 @cindex syntax highlighting and coloring
181 Font Lock mode is a minor mode, always local to a particular
182 buffer, which highlights (or ``fontifies'') using various faces
183 according to the syntax of the text you are editing. It can
184 recognize comments and strings in most languages; in several
185 languages, it can also recognize and properly highlight various other
186 important constructs---for example, names of functions being defined
187 or reserved keywords.
189 @findex font-lock-mode
190 @findex turn-on-font-lock
191 The command @kbd{M-x font-lock-mode} turns Font Lock mode on or off
192 according to the argument, and toggles the mode when it has no argument.
193 The function @code{turn-on-font-lock} unconditionally enables Font Lock
194 mode. This is useful in mode-hook functions. For example, to enable
195 Font Lock mode whenever you edit a C file, you can do this:
198 (add-hook 'c-mode-hook 'turn-on-font-lock)
201 @findex global-font-lock-mode
202 @vindex global-font-lock-mode
203 To turn on Font Lock mode automatically in all modes which support
204 it, customize the user option @code{global-font-lock-mode} or use the
205 function @code{global-font-lock-mode} in your @file{.emacs} file, like
209 (global-font-lock-mode 1)
212 Font Lock mode uses several specifically named faces to do its job,
213 including @code{font-lock-string-face}, @code{font-lock-comment-face},
214 and others. The easiest way to find them all is to use completion
215 on the face name in @code{set-face-foreground}.
217 To change the colors or the fonts used by Font Lock mode to fontify
218 different parts of text, just change these faces. There are
223 Invoke @kbd{M-x set-face-foreground} or @kbd{M-x set-face-background}
224 to change the colors of a particular face used by Font Lock.
225 @xref{Faces}. The command @kbd{M-x list-faces-display} displays all
226 the faces currently known to Emacs, including those used by Font Lock.
229 Customize the faces interactively with @kbd{M-x customize-face}, as
230 described in @ref{Face Customization}.
233 To get the full benefit of Font Lock mode, you need to choose a
234 default font which has bold, italic, and bold-italic variants; or else
235 you need to have a color or gray-scale screen.
237 @vindex font-lock-maximum-decoration
238 The variable @code{font-lock-maximum-decoration} specifies the
239 preferred level of fontification, for modes that provide multiple
240 levels. Level 1 is the least amount of fontification; some modes
241 support levels as high as 3. The normal default is ``as high as
242 possible.'' You can specify an integer, which applies to all modes, or
243 you can specify different numbers for particular major modes; for
244 example, to use level 1 for C/C++ modes, and the default level
248 (setq font-lock-maximum-decoration
249 '((c-mode . 1) (c++-mode . 1)))
252 @vindex font-lock-maximum-size
253 Fontification can be too slow for large buffers, so you can suppress
254 it. The variable @code{font-lock-maximum-size} specifies a buffer size,
255 beyond which buffer fontification is suppressed.
257 @c @w is used below to prevent a bad page-break.
258 @vindex font-lock-beginning-of-syntax-function
259 Comment and string fontification (or ``syntactic'' fontification)
260 relies on analysis of the syntactic structure of the buffer text. For
261 the sake of speed, some modes, including C mode and Lisp mode,
262 rely on a special convention: an open-parenthesis or open-brace in the
263 leftmost column always defines the @w{beginning} of a defun, and is
264 thus always outside any string or comment. (@xref{Left Margin
265 Paren}.) If you don't follow this convention, Font Lock mode can
266 misfontify the text that follows an open-parenthesis or open-brace in
267 the leftmost column that is inside a string or comment.
269 @cindex slow display during scrolling
270 The variable @code{font-lock-beginning-of-syntax-function} (always
271 buffer-local) specifies how Font Lock mode can find a position
272 guaranteed to be outside any comment or string. In modes which use the
273 leftmost column parenthesis convention, the default value of the variable
274 is @code{beginning-of-defun}---that tells Font Lock mode to use the
275 convention. If you set this variable to @code{nil}, Font Lock no longer
276 relies on the convention. This avoids incorrect results, but the price
277 is that, in some cases, fontification for a changed text must rescan
278 buffer text from the beginning of the buffer. This can considerably
279 slow down redisplay while scrolling, particularly if you are close to
280 the end of a large buffer.
282 @findex font-lock-add-keywords
283 Font Lock highlighting patterns already exist for many modes, but you
284 may want to fontify additional patterns. You can use the function
285 @code{font-lock-add-keywords}, to add your own highlighting patterns for
286 a particular mode. For example, to highlight @samp{FIXME:} words in C
290 (font-lock-add-keywords
292 '(("\\<\\(FIXME\\):" 1 font-lock-warning-face t)))
295 @node Highlight Changes
296 @section Highlight Changes Mode
298 @findex highlight-changes-mode
299 Use @kbd{M-x highlight-changes-mode} to enable a minor mode
300 that uses faces (colors, typically) to indicate which parts of
301 the buffer were changed most recently.
303 @node Highlight Interactively
304 @section Interactive Highlighting by Matching
305 @cindex highlighting by matching
306 @cindex interactive highlighting
308 It is sometimes useful to highlight the strings that match a certain
309 regular expression. For example, you might wish to see all the
310 references to a certain variable in a program source file, or highlight
311 certain parts in a voluminous output of some program, or make certain
312 cliches stand out in an article.
315 Use the @kbd{M-x hi-lock-mode} command to turn on a minor mode that
316 allows you to specify regular expressions of the text to be
317 highlighted. Hi-lock mode works like Font Lock (@pxref{Font Lock}),
318 except that it lets you specify explicitly what parts of text to
319 highlight. You control Hi-lock mode with these commands:
322 @item C-x w h @var{regexp} @key{RET} @var{face} @key{RET}
324 @findex highlight-regexp
325 Highlight text that matches
326 @var{regexp} using face @var{face} (@code{highlight-regexp}).
327 By using this command more than once, you can highlight various
328 parts of the text in different ways.
330 @item C-x w r @var{regexp} @key{RET}
332 @findex unhighlight-regexp
333 Unhighlight @var{regexp} (@code{unhighlight-regexp}). You must enter
334 one of the regular expressions currently specified for highlighting.
335 (You can use completion, or choose from a menu, to enter one of them
338 @item C-x w l @var{regexp} @key{RET} @var{face} @key{RET}
340 @findex highlight-lines-matching-regexp
341 @cindex lines, highlighting
342 @cindex highlighting lines of text
343 Highlight entire lines containing a match for @var{regexp}, using face
344 @var{face} (@code{highlight-lines-matching-regexp}).
348 @findex hi-lock-write-interactive-patterns
349 Insert all the current highlighting regexp/face pairs into the buffer
350 at point, with comment delimiters to prevent them from changing your
351 program. This key binding runs the
352 @code{hi-lock-write-interactive-patterns} command.
354 These patterns will be read the next time you visit the file while
355 Hi-lock mode is enabled, or whenever you use the @kbd{M-x
356 hi-lock-find-patterns} command.
360 @findex hi-lock-find-patterns
361 @vindex hi-lock-exclude-modes
362 Re-read regexp/face pairs in the current buffer
363 (@code{hi-lock-write-interactive-patterns}). The list of pairs is
364 found no matter where in the buffer it may be.
366 This command does nothing if the major mode is a member of the list
367 @code{hi-lock-exclude-modes}.
370 @node Trailing Whitespace
371 @section Trailing Whitespace
373 @cindex trailing whitespace
374 @cindex whitespace, trailing
375 @vindex show-trailing-whitespace
376 It is easy to leave unnecessary spaces at the end of a line without
377 realizing it. In most cases, this @dfn{trailing whitespace} has no
378 effect, but there are special circumstances where it matters.
380 You can make trailing whitespace visible on the screen by setting the
381 buffer-local variable @code{show-trailing-whitespace} to @code{t}. Then
382 Emacs displays trailing whitespace in the face
383 @code{trailing-whitespace}.
385 Trailing whitespace is defined as spaces or tabs at the end of a
386 line. But trailing whitespace is not displayed specially if point is
387 at the end of the line containing the whitespace. (Doing that looks
388 ugly while you are typing in new text, and the location of point is
389 enough in that case to show you that the spaces are present.)
391 @findex delete-trailing-whitespace
392 To delete all trailing whitespace within the current buffer's
393 restriction (@pxref{Narrowing}), type @kbd{M-x
394 delete-trailing-whitespace @key{RET}}. (This command does not remove
395 the form-feed characters.)
397 @vindex indicate-empty-lines
398 @vindex default-indicate-empty-lines
400 Emacs can indicate empty lines at the end of the buffer with a
401 special bitmap on the left fringe of the window. To enable this
402 feature, set the buffer-local variable @code{indicate-empty-lines} to
403 a non-@code{nil} value. The default value of this variable is
404 controlled by the variable @code{default-indicate-empty-lines};
405 by setting that variable, you can enable or disable this feature
411 If a buffer contains text that is too large to fit entirely within a
412 window that is displaying the buffer, Emacs shows a contiguous portion of
413 the text. The portion shown always contains point.
416 @dfn{Scrolling} means moving text up or down in the window so that
417 different parts of the text are visible. Scrolling forward means that text
418 moves up, and new text appears at the bottom. Scrolling backward moves
419 text down and new text appears at the top.
421 Scrolling happens automatically if you move point past the bottom or top
422 of the window. You can also explicitly request scrolling with the commands
427 Clear screen and redisplay, scrolling the selected window to center
428 point vertically within it (@code{recenter}).
430 Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}).
432 @itemx @key{PAGEDOWN}
433 Likewise, scroll forward.
435 Scroll backward (@code{scroll-down}).
438 Likewise, scroll backward.
440 Scroll so point is on line @var{arg} (@code{recenter}).
442 Scroll heuristically to bring useful information onto the screen
443 (@code{reposition-window}).
448 The most basic scrolling command is @kbd{C-l} (@code{recenter}) with
449 no argument. It clears the entire screen and redisplays all windows.
450 In addition, it scrolls the selected window so that point is halfway
451 down from the top of the window.
461 @vindex next-screen-context-lines
462 To read the buffer a windowful at a time, use @kbd{C-v}
463 (@code{scroll-up}) with no argument. This scrolls forward by nearly
464 the whole window height. The effect is to take the two lines at the
465 bottom of the window and put them at the top, followed by nearly a
466 whole windowful of lines that were not previously visible. If point
467 was in the text that scrolled off the top, it ends up at the new top
470 @kbd{M-v} (@code{scroll-down}) with no argument scrolls backward in
471 a similar way, also with overlap. The number of lines of overlap
472 across a @kbd{C-v} or @kbd{M-v} is controlled by the variable
473 @code{next-screen-context-lines}; by default, it is 2. The function
474 keys @key{NEXT} and @key{PRIOR}, or @key{PAGEDOWN} and @key{PAGEUP},
475 are equivalent to @kbd{C-v} and @kbd{M-v}.
477 The commands @kbd{C-v} and @kbd{M-v} with a numeric argument scroll
478 the text in the selected window up or down a few lines. @kbd{C-v}
479 with an argument moves the text and point up, together, that many
480 lines; it brings the same number of new lines into view at the bottom
481 of the window. @kbd{M-v} with numeric argument scrolls the text
482 downward, bringing that many new lines into view at the top of the
483 window. @kbd{C-v} with a negative argument is like @kbd{M-v} and vice
486 The names of scroll commands are based on the direction that the
487 text moves in the window. Thus, the command to scroll forward is
488 called @code{scroll-up} because it moves the text upward on the
489 screen. The keys @key{PAGEDOWN} and @key{PAGEUP} derive their names
490 and customary meanings from a different convention that developed
491 elsewhere; hence the strange result that @key{PAGEDOWN} runs
494 @vindex scroll-preserve-screen-position
495 Some users like the full-screen scroll commands to keep point at the
496 same screen line. To enable this behavior, set the variable
497 @code{scroll-preserve-screen-position} to a non-@code{nil} value. This
498 mode is convenient for browsing through a file by scrolling by
499 screenfuls; if you come back to the screen where you started, point goes
500 back to the line where it started. However, this mode is inconvenient
501 when you move to the next screen in order to move point to the text
504 Another way to do scrolling is with @kbd{C-l} with a numeric argument.
505 @kbd{C-l} does not clear the screen when given an argument; it only scrolls
506 the selected window. With a positive argument @var{n}, it repositions text
507 to put point @var{n} lines down from the top. An argument of zero puts
508 point on the very top line. Point does not move with respect to the text;
509 rather, the text and point move rigidly on the screen. @kbd{C-l} with a
510 negative argument puts point that many lines from the bottom of the window.
511 For example, @kbd{C-u - 1 C-l} puts point on the bottom line, and @kbd{C-u
512 - 5 C-l} puts it five lines from the bottom. @kbd{C-u C-l} scrolls to put
513 point at the center (vertically) of the selected window.
516 @findex reposition-window
517 The @kbd{C-M-l} command (@code{reposition-window}) scrolls the current
518 window heuristically in a way designed to get useful information onto
519 the screen. For example, in a Lisp file, this command tries to get the
520 entire current defun onto the screen if possible.
522 @vindex scroll-conservatively
523 Scrolling happens automatically when point moves out of the visible
524 portion of the text. Normally, automatic scrolling centers point
525 vertically within the window. However, if you set
526 @code{scroll-conservatively} to a small number @var{n}, then if you
527 move point just a little off the screen---less than @var{n}
528 lines---then Emacs scrolls the text just far enough to bring point
529 back on screen. By default, @code{scroll-conservatively} is 0.
531 @cindex aggressive scrolling
532 @vindex scroll-up-aggressively
533 @vindex scroll-down-aggressively
534 When the window does scroll by a longer distance, you can control
535 how aggressively it scrolls, by setting the variables
536 @code{scroll-up-aggressively} and @code{scroll-down-aggressively}.
537 The value of @code{scroll-up-aggressively} should be either
538 @code{nil}, or a fraction @var{f} between 0 and 1. A fraction
539 specifies where on the screen to put point when scrolling upward.
540 More precisely, when a window scrolls up because point is above the
541 window start, the new start position is chosen to put point @var{f}
542 part of the window height from the top. The larger @var{f}, the more
543 aggressive the scrolling.
545 @code{nil}, which is the default, scrolls to put point at the center.
546 So it is equivalent to .5.
548 Likewise, @code{scroll-down-aggressively} is used for scrolling
549 down. The value, @var{f}, specifies how far point should be placed
550 from the bottom of the window; thus, as with
551 @code{scroll-up-aggressively}, a larger value is more aggressive.
553 @vindex scroll-margin
554 The variable @code{scroll-margin} restricts how close point can come
555 to the top or bottom of a window. Its value is a number of screen
556 lines; if point comes within that many lines of the top or bottom of the
557 window, Emacs recenters the window. By default, @code{scroll-margin} is
560 @node Horizontal Scrolling
561 @section Horizontal Scrolling
562 @cindex horizontal scrolling
564 @dfn{Horizontal scrolling} means shifting all the lines sideways
565 within a window---so that some of the text near the left margin is not
566 displayed at all. Emacs does this automatically in any window that
567 uses line truncation rather than continuation: whenever point moves
568 off the left or right edge of the screen, Emacs scrolls the buffer
569 horizontally to make point visible.
571 When a window has been scrolled horizontally, text lines are truncated
572 rather than continued (@pxref{Continuation Lines}), with a @samp{$}
573 appearing in the first column when there is text truncated to the left,
574 and in the last column when there is text truncated to the right.
576 You can use these commands to do explicit horizontal scrolling.
580 Scroll text in current window to the left (@code{scroll-left}).
582 Scroll to the right (@code{scroll-right}).
589 The command @kbd{C-x <} (@code{scroll-left}) scrolls the selected
590 window to the left by @var{n} columns with argument @var{n}. This moves
591 part of the beginning of each line off the left edge of the window.
592 With no argument, it scrolls by almost the full width of the window (two
593 columns less, to be precise).
595 @kbd{C-x >} (@code{scroll-right}) scrolls similarly to the right. The
596 window cannot be scrolled any farther to the right once it is displayed
597 normally (with each line starting at the window's left margin);
598 attempting to do so has no effect. This means that you don't have to
599 calculate the argument precisely for @w{@kbd{C-x >}}; any sufficiently large
600 argument will restore the normal display.
602 If you scroll a window horizontally by hand, that sets a lower bound
603 for automatic horizontal scrolling. Automatic scrolling will continue
604 to scroll the window, but never farther to the right than the amount
605 you previously set by @code{scroll-left}.
607 @vindex automatic-hscrolling
608 To disable automatic horizontal scrolling, set the variable
609 @code{automatic-hscrolling} to @code{nil}.
616 @cindex windows, synchronizing
617 @cindex synchronizing windows
619 @dfn{Follow mode} is a minor mode that makes two windows showing the
620 same buffer scroll as one tall ``virtual window.'' To use Follow mode,
621 go to a frame with just one window, split it into two side-by-side
622 windows using @kbd{C-x 3}, and then type @kbd{M-x follow-mode}. From
623 then on, you can edit the buffer in either of the two windows, or scroll
624 either one; the other window follows it.
626 In Follow mode, if you move point outside the portion visible in one
627 window and into the portion visible in the other window, that selects
628 the other window---again, treating the two as if they were parts of
631 To turn off Follow mode, type @kbd{M-x follow-mode} a second time.
633 @node Selective Display
634 @section Selective Display
635 @cindex selective display
636 @findex set-selective-display
639 Emacs has the ability to hide lines indented more than a certain number
640 of columns (you specify how many columns). You can use this to get an
641 overview of a part of a program.
643 To hide lines, type @kbd{C-x $} (@code{set-selective-display}) with a
644 numeric argument @var{n}. Then lines with at least @var{n} columns of
645 indentation disappear from the screen. The only indication of their
646 presence is that three dots (@samp{@dots{}}) appear at the end of each
647 visible line that is followed by one or more hidden ones.
649 The commands @kbd{C-n} and @kbd{C-p} move across the hidden lines as
650 if they were not there.
652 The hidden lines are still present in the buffer, and most editing
653 commands see them as usual, so you may find point in the middle of the
654 hidden text. When this happens, the cursor appears at the end of the
655 previous line, after the three dots. If point is at the end of the
656 visible line, before the newline that ends it, the cursor appears before
659 To make all lines visible again, type @kbd{C-x $} with no argument.
661 @vindex selective-display-ellipses
662 If you set the variable @code{selective-display-ellipses} to
663 @code{nil}, the three dots do not appear at the end of a line that
664 precedes hidden lines. Then there is no visible indication of the
665 hidden lines. This variable becomes local automatically when set.
667 @node Optional Mode Line
668 @section Optional Mode Line Features
670 @cindex line number display
671 @cindex display of line number
672 @findex line-number-mode
673 The current line number of point appears in the mode line when Line
674 Number mode is enabled. Use the command @kbd{M-x line-number-mode} to
675 turn this mode on and off; normally it is on. The line number appears
676 before the buffer percentage @var{pos}, with the letter @samp{L} to
677 indicate what it is. @xref{Minor Modes}, for more information about
678 minor modes and about how to use this command.
680 @cindex narrowing, and line number display
681 If you have narrowed the buffer (@pxref{Narrowing}), the displayed
682 line number is relative to the accessible portion of the buffer.
684 @vindex line-number-display-limit
685 If the buffer is very large (larger than the value of
686 @code{line-number-display-limit}), then the line number doesn't appear.
687 Emacs doesn't compute the line number when the buffer is large, because
688 that would be too slow. Set it to @code{nil} to remove the limit.
690 @vindex line-number-display-limit-width
691 Line-number computation can also be slow if the lines in the buffer
692 are too long. For this reason, Emacs normally doesn't display line
693 numbers if the average width, in characters, of lines near point is
694 larger than the value of the variable
695 @code{line-number-display-limit-width}. The default value is 200
698 @cindex Column Number mode
699 @cindex mode, Column Number
700 @findex column-number-mode
701 You can also display the current column number by turning on Column
702 Number mode. It displays the current column number preceded by the
703 letter @samp{C}. Type @kbd{M-x column-number-mode} to toggle this mode.
706 @cindex time (on mode line)
707 Emacs can optionally display the time and system load in all mode
708 lines. To enable this feature, type @kbd{M-x display-time} or customize
709 the option @code{display-time-mode}. The information added to the mode
710 line usually appears after the buffer name, before the mode names and
711 their parentheses. It looks like this:
714 @var{hh}:@var{mm}pm @var{l.ll}
718 @vindex display-time-24hr-format
719 Here @var{hh} and @var{mm} are the hour and minute, followed always by
720 @samp{am} or @samp{pm}. @var{l.ll} is the average number of running
721 processes in the whole system recently. (Some fields may be missing if
722 your operating system cannot support them.) If you prefer time display
723 in 24-hour format, set the variable @code{display-time-24hr-format}
726 @cindex mail (on mode line)
727 @vindex display-time-use-mail-icon
728 @vindex display-time-mail-face
729 The word @samp{Mail} appears after the load level if there is mail
730 for you that you have not read yet. On a graphical display you can use
731 an icon instead of @samp{Mail} by customizing
732 @code{display-time-use-mail-icon}; this may save some space on the mode
733 line. You can customize @code{display-time-mail-face} to make the mail
736 @cindex mode line, 3D appearence
737 @cindex attributes of mode line, changing
738 @cindex non-integral number of lines in a window
739 By default, the mode line is drawn on graphics displays with
740 3D-style highlighting, like that of a button when it is not being
741 pressed. If you don't like this effect, you can disable the 3D
742 highlighting of the mode line, by customizing the attributes of the
743 @code{mode-line} face in your @file{.emacs} init file, like this:
746 (set-face-attribute 'mode-line nil :box nil)
750 Alternatively, you can turn off the box attribute in your
751 @file{.Xdefaults} file:
754 Emacs.mode-line.AttributeBox: off
758 @section How Text Is Displayed
759 @cindex characters (in text)
761 ASCII printing characters (octal codes 040 through 0176) in Emacs
762 buffers are displayed with their graphics, as are non-ASCII multibyte
763 printing characters (octal codes above 0400).
765 Some ASCII control characters are displayed in special ways. The
766 newline character (octal code 012) is displayed by starting a new line.
767 The tab character (octal code 011) is displayed by moving to the next
768 tab stop column (normally every 8 columns).
770 Other ASCII control characters are normally displayed as a caret
771 (@samp{^}) followed by the non-control version of the character; thus,
772 control-A is displayed as @samp{^A}.
774 Non-ASCII characters 0200 through 0237 (octal) are displayed with
775 octal escape sequences; thus, character code 0230 (octal) is displayed
776 as @samp{\230}. The display of character codes 0240 through 0377
777 (octal) may be either as escape sequences or as graphics. They do not
778 normally occur in multibyte buffers, but if they do, they are displayed
779 as Latin-1 graphics. In unibyte mode, if you enable European display
780 they are displayed using their graphics (assuming your terminal supports
781 them), otherwise as escape sequences. @xref{Single-Byte Character
785 @section Customization of Display
787 This section contains information for customization only. Beginning
788 users should skip it.
790 @vindex mode-line-inverse-video
791 The variable @code{mode-line-inverse-video} is an obsolete way of
792 controlling whether the mode line is displayed in inverse video; the
793 preferred way of doing this is to change the @code{mode-line} face.
794 @xref{Mode Line}. However, if @code{mode-line-inverse-video} has a
795 value of @code{nil}, then the @code{mode-line} face will be ignored,
796 and mode-lines will be drawn using the default text face.
799 @vindex inverse-video
800 If the variable @code{inverse-video} is non-@code{nil}, Emacs attempts
801 to invert all the lines of the display from what they normally are.
804 If the variable @code{visible-bell} is non-@code{nil}, Emacs attempts
805 to make the whole screen blink when it would normally make an audible bell
806 sound. This variable has no effect if your terminal does not have a way
807 to make the screen blink.@refill
809 @vindex no-redraw-on-reenter
810 When you reenter Emacs after suspending, Emacs normally clears the
811 screen and redraws the entire display. On some terminals with more than
812 one page of memory, it is possible to arrange the termcap entry so that
813 the @samp{ti} and @samp{te} strings (output to the terminal when Emacs
814 is entered and exited, respectively) switch between pages of memory so
815 as to use one page for Emacs and another page for other output. Then
816 you might want to set the variable @code{no-redraw-on-reenter}
817 non-@code{nil}; this tells Emacs to assume, when resumed, that the
818 screen page it is using still contains what Emacs last wrote there.
820 @vindex echo-keystrokes
821 The variable @code{echo-keystrokes} controls the echoing of multi-character
822 keys; its value is the number of seconds of pause required to cause echoing
823 to start, or zero meaning don't echo at all. @xref{Echo Area}.
826 If the variable @code{ctl-arrow} is @code{nil}, all control characters in
827 the buffer are displayed with octal escape sequences, except for newline
828 and tab. Altering the value of @code{ctl-arrow} makes it local to the
829 current buffer; until that time, the default value is in effect. The
830 default is initially @code{t}. @xref{Display Tables,, Display Tables,
831 elisp, The Emacs Lisp Reference Manual}.
834 Normally, a tab character in the buffer is displayed as whitespace which
835 extends to the next display tab stop position, and display tab stops come
836 at intervals equal to eight spaces. The number of spaces per tab is
837 controlled by the variable @code{tab-width}, which is made local by
838 changing it, just like @code{ctl-arrow}. Note that how the tab character
839 in the buffer is displayed has nothing to do with the definition of
840 @key{TAB} as a command. The variable @code{tab-width} must have an
841 integer value between 1 and 1000, inclusive.
843 @c @vindex truncate-lines @c No index entry here, because we have one
844 @c in the continuation section.
845 If the variable @code{truncate-lines} is non-@code{nil}, then each
846 line of text gets just one screen line for display; if the text line is
847 too long, display shows only the part that fits. If
848 @code{truncate-lines} is @code{nil}, then long text lines display as
849 more than one screen line, enough to show the whole text of the line.
850 @xref{Continuation Lines}. Altering the value of @code{truncate-lines}
851 makes it local to the current buffer; until that time, the default value
852 is in effect. The default is initially @code{nil}.
854 @c @vindex truncate-partial-width-windows @c Idx entry is in Split Windows.
855 If the variable @code{truncate-partial-width-windows} is
856 non-@code{nil}, it forces truncation rather than continuation in any
857 window less than the full width of the screen or frame, regardless of
858 the value of @code{truncate-lines}. For information about side-by-side
859 windows, see @ref{Split Window}. See also @ref{Display,, Display,
860 elisp, The Emacs Lisp Reference Manual}.
863 The variable @code{baud-rate} holds the output speed of the
864 terminal, as far as Emacs knows. Setting this variable does not
865 change the speed of actual data transmission, but the value is used
866 for calculations. On terminals, it affects padding, and decisions
867 about whether to scroll part of the screen or redraw it instead.
868 It also affects the behavior of incremental search.
870 On window-systems, @code{baud-rate} is only used to determine how
871 frequently to look for pending input during display updating. A
872 higher value of @code{baud-rate} means that check for pending input
873 will be done less frequently.
875 You can customize the way any particular character code is displayed
876 by means of a display table. @xref{Display Tables,, Display Tables,
877 elisp, The Emacs Lisp Reference Manual}.
879 @cindex hourglass pointer display
880 @vindex hourglass-delay
881 On a window system, Emacs can optionally display the mouse pointer
882 in a special shape to say that Emacs is busy. To turn this feature on
883 or off, customize the group @code{cursor}. You can also control the
884 amount of time Emacs must remain busy before the busy indicator is
885 displayed, by setting the variable @code{hourglass-delay}.
888 @section Displaying the Cursor
891 @cindex highlight current line
892 @findex blink-cursor-mode
893 @cindex cursor, locating visually
894 @cindex cursor, blinking
895 There are a number of ways to customize the display of the cursor.
896 @kbd{M-x hl-line-mode} enables or disables a global minor mode which
897 highlights the line containing point. On window systems, the command
898 @kbd{M-x blink-cursor-mode} turns on or off the blinking of the
899 cursor. (On terminals, the terminal itself blinks the cursor, and
900 Emacs has no control over it.)
902 You can customize the cursor's color, and whether it blinks, using
903 the @code{cursor} Custom group (@pxref{Easy Customization}).
905 @vindex x-stretch-cursor
906 @cindex wide block cursor
907 When displaying on a window system, Emacs can optionally draw the
908 block cursor as wide as the character under the cursor---for example,
909 if the cursor is on a tab character, it would cover the full width
910 occupied by that tab character. To enable this feature, set the
911 variable @code{x-stretch-cursor} to a non-@code{nil} value.
913 @cindex cursor in non-selected windows
914 @vindex cursor-in-non-selected-windows
915 Normally, the cursor in non-selected windows is shown as a hollow box.
916 To turn off cursor display in non-selected windows, customize the option
917 @code{cursor-in-non-selected-windows} to assign it a @code{nil} value.