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802b0ea7 | 1 | @c This is part of the Emacs manual. |
b65d8176 | 2 | @c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001, |
3f548a7c | 3 | @c 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc. |
6bf7aab6 DL |
4 | @c See file emacs.texi for copying conditions. |
5 | @node Display, Search, Registers, Top | |
6 | @chapter Controlling the Display | |
7 | ||
8 | Since only part of a large buffer fits in the window, Emacs tries to | |
43d67313 RS |
9 | show a part that is likely to be interesting. Display-control |
10 | commands allow you to specify which part of the text you want to see, | |
11 | and how to display it. Many variables also affect the details of | |
12 | redisplay. Unless otherwise stated, the variables described in this | |
13 | chapter have their effect by customizing redisplay itself; therefore, | |
14 | their values only make a difference at the time of redisplay. | |
6bf7aab6 DL |
15 | |
16 | @menu | |
43d67313 RS |
17 | * Scrolling:: Commands to move text up and down in a window. |
18 | * Auto Scrolling:: Redisplay scrolls text automatically when needed. | |
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19 | * Horizontal Scrolling:: Moving text left and right in a window. |
20 | * Follow Mode:: Follow mode lets two windows scroll as one. | |
b8f3a9e3 | 21 | * Faces:: How to change the display style using faces. |
43d08eb9 | 22 | * Standard Faces:: Emacs' predefined faces. |
b8f3a9e3 | 23 | * Font Lock:: Minor mode for syntactic highlighting using faces. |
b8f3a9e3 | 24 | * Highlight Interactively:: Tell Emacs what text to highlight. |
fad78d58 | 25 | * Fringes:: Enabling or disabling window fringes. |
9d2908a6 | 26 | * Displaying Boundaries:: Displaying top and bottom of the buffer. |
fad78d58 | 27 | * Useless Whitespace:: Showing possibly-spurious trailing whitespace. |
6bf7aab6 DL |
28 | * Selective Display:: Hiding lines with lots of indentation. |
29 | * Optional Mode Line:: Optional mode line display features. | |
30 | * Text Display:: How text characters are normally displayed. | |
099bfef9 | 31 | * Cursor Display:: Features for displaying the cursor. |
9d2908a6 RS |
32 | * Line Truncation:: Truncating lines to fit the screen width instead |
33 | of continuing them to multiple screen lines. | |
9d3d42fb | 34 | * Temporary Face Changes:: Commands to temporarily modify the default text face |
0015d677 | 35 | * Display Custom:: Information on variables for customizing display. |
6bf7aab6 DL |
36 | @end menu |
37 | ||
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38 | @node Scrolling |
39 | @section Scrolling | |
40 | ||
41 | If a buffer contains text that is too large to fit entirely within a | |
42 | window that is displaying the buffer, Emacs shows a contiguous portion of | |
43 | the text. The portion shown always contains point. | |
44 | ||
45 | @cindex scrolling | |
46 | @dfn{Scrolling} means moving text up or down in the window so that | |
47 | different parts of the text are visible. Scrolling ``forward'' or | |
48 | ``up'' means that text moves up, and new text appears at the bottom. | |
49 | Scrolling ``backward'' or ``down'' moves text down, and new text | |
50 | appears at the top. | |
51 | ||
52 | Scrolling happens automatically if you move point past the bottom or | |
53 | top of the window. You can also scroll explicitly with the commands | |
54 | in this section. | |
55 | ||
56 | @table @kbd | |
57 | @item C-l | |
58 | Clear screen and redisplay, scrolling the selected window to center | |
59 | point vertically within it (@code{recenter}). | |
60 | @item C-v | |
61 | Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}). | |
62 | @item @key{NEXT} | |
63 | @itemx @key{PAGEDOWN} | |
64 | Likewise, scroll forward. | |
65 | @item M-v | |
66 | Scroll backward (@code{scroll-down}). | |
67 | @item @key{PRIOR} | |
68 | @itemx @key{PAGEUP} | |
69 | Likewise, scroll backward. | |
70 | @item @var{arg} C-l | |
71 | Scroll so point is on line @var{arg} (@code{recenter}). | |
72 | @item C-M-l | |
73 | Scroll heuristically to bring useful information onto the screen | |
74 | (@code{reposition-window}). | |
75 | @end table | |
76 | ||
77 | @kindex C-l | |
78 | @findex recenter | |
79 | The most basic scrolling command is @kbd{C-l} (@code{recenter}) with | |
80 | no argument. It scrolls the selected window so that point is halfway | |
81 | down from the top of the window. On a text terminal, it also clears | |
82 | the screen and redisplays all windows. That is useful in case the | |
83 | screen is garbled (@pxref{Screen Garbled}). | |
84 | ||
85 | @kindex C-v | |
86 | @kindex M-v | |
87 | @kindex NEXT | |
88 | @kindex PRIOR | |
89 | @kindex PAGEDOWN | |
90 | @kindex PAGEUP | |
91 | @findex scroll-up | |
92 | @findex scroll-down | |
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93 | To read the buffer a windowful at a time, use @kbd{C-v} |
94 | (@code{scroll-up}) with no argument. This scrolls forward by nearly | |
95 | the whole window height. The effect is to take the two lines at the | |
96 | bottom of the window and put them at the top, followed by nearly a | |
97 | whole windowful of lines that were not previously visible. If point | |
98 | was in the text that scrolled off the top, it ends up at the new top | |
99 | of the window. | |
100 | ||
43d67313 | 101 | @vindex next-screen-context-lines |
dc917bd9 | 102 | @kbd{M-v} (@code{scroll-down}) with no argument scrolls backward in |
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103 | a similar way, also with overlap. The number of lines of overlap that |
104 | the @kbd{C-v} or @kbd{M-v} commands leave is controlled by the | |
105 | variable @code{next-screen-context-lines}; by default, it is 2. The | |
106 | function keys @key{NEXT} and @key{PRIOR}, or @key{PAGEDOWN} and | |
107 | @key{PAGEUP}, are equivalent to @kbd{C-v} and @kbd{M-v}. | |
dc917bd9 RS |
108 | |
109 | The commands @kbd{C-v} and @kbd{M-v} with a numeric argument scroll | |
110 | the text in the selected window up or down a few lines. @kbd{C-v} | |
111 | with an argument moves the text and point up, together, that many | |
112 | lines; it brings the same number of new lines into view at the bottom | |
113 | of the window. @kbd{M-v} with numeric argument scrolls the text | |
114 | downward, bringing that many new lines into view at the top of the | |
115 | window. @kbd{C-v} with a negative argument is like @kbd{M-v} and vice | |
116 | versa. | |
117 | ||
118 | The names of scroll commands are based on the direction that the | |
119 | text moves in the window. Thus, the command to scroll forward is | |
120 | called @code{scroll-up} because it moves the text upward on the | |
121 | screen. The keys @key{PAGEDOWN} and @key{PAGEUP} derive their names | |
122 | and customary meanings from a different convention that developed | |
123 | elsewhere; hence the strange result that @key{PAGEDOWN} runs | |
124 | @code{scroll-up}. | |
125 | ||
126 | @vindex scroll-preserve-screen-position | |
127 | Some users like the full-screen scroll commands to keep point at the | |
128 | same screen line. To enable this behavior, set the variable | |
129 | @code{scroll-preserve-screen-position} to a non-@code{nil} value. In | |
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130 | this mode, when these commands would scroll the text around point off |
131 | the screen, or within @code{scroll-margin} lines of the edge, they | |
c39bed4b | 132 | move point to keep the same vertical position within the window. |
43d67313 RS |
133 | This mode is convenient for browsing through a file by scrolling by |
134 | screenfuls; if you come back to the screen where you started, point | |
135 | goes back to the line where it started. However, this mode is | |
136 | inconvenient when you move to the next screen in order to move point | |
137 | to the text there. | |
dc917bd9 RS |
138 | |
139 | Another way to do scrolling is with @kbd{C-l} with a numeric argument. | |
140 | @kbd{C-l} does not clear the screen when given an argument; it only scrolls | |
141 | the selected window. With a positive argument @var{n}, it repositions text | |
142 | to put point @var{n} lines down from the top. An argument of zero puts | |
143 | point on the very top line. Point does not move with respect to the text; | |
144 | rather, the text and point move rigidly on the screen. @kbd{C-l} with a | |
145 | negative argument puts point that many lines from the bottom of the window. | |
146 | For example, @kbd{C-u - 1 C-l} puts point on the bottom line, and @kbd{C-u | |
147 | - 5 C-l} puts it five lines from the bottom. @kbd{C-u C-l} scrolls to put | |
148 | point at the center (vertically) of the selected window. | |
149 | ||
150 | @kindex C-M-l | |
151 | @findex reposition-window | |
152 | The @kbd{C-M-l} command (@code{reposition-window}) scrolls the current | |
153 | window heuristically in a way designed to get useful information onto | |
154 | the screen. For example, in a Lisp file, this command tries to get the | |
155 | entire current defun onto the screen if possible. | |
156 | ||
43d67313 RS |
157 | @node Auto Scrolling |
158 | @section Automatic Scrolling | |
159 | ||
dc917bd9 | 160 | @vindex scroll-conservatively |
43d67313 RS |
161 | Redisplay scrolls the buffer automatically when point moves out of |
162 | the visible portion of the text. The purpose of automatic scrolling | |
163 | is to make point visible, but you can customize many aspects of how | |
164 | this is done. | |
165 | ||
166 | Normally, automatic scrolling centers point vertically within the | |
167 | window. However, if you set @code{scroll-conservatively} to a small | |
168 | number @var{n}, then if you move point just a little off the | |
169 | screen---less than @var{n} lines---then Emacs scrolls the text just | |
170 | far enough to bring point back on screen. By default, | |
9705fb37 | 171 | @code{scroll-conservatively} is@tie{}0. |
dc917bd9 RS |
172 | |
173 | @cindex aggressive scrolling | |
174 | @vindex scroll-up-aggressively | |
175 | @vindex scroll-down-aggressively | |
176 | When the window does scroll by a longer distance, you can control | |
177 | how aggressively it scrolls, by setting the variables | |
178 | @code{scroll-up-aggressively} and @code{scroll-down-aggressively}. | |
179 | The value of @code{scroll-up-aggressively} should be either | |
180 | @code{nil}, or a fraction @var{f} between 0 and 1. A fraction | |
181 | specifies where on the screen to put point when scrolling upward. | |
182 | More precisely, when a window scrolls up because point is above the | |
183 | window start, the new start position is chosen to put point @var{f} | |
184 | part of the window height from the top. The larger @var{f}, the more | |
185 | aggressive the scrolling. | |
186 | ||
187 | @code{nil}, which is the default, scrolls to put point at the center. | |
188 | So it is equivalent to .5. | |
189 | ||
190 | Likewise, @code{scroll-down-aggressively} is used for scrolling | |
191 | down. The value, @var{f}, specifies how far point should be placed | |
192 | from the bottom of the window; thus, as with | |
193 | @code{scroll-up-aggressively}, a larger value is more aggressive. | |
194 | ||
195 | @vindex scroll-margin | |
196 | The variable @code{scroll-margin} restricts how close point can come | |
197 | to the top or bottom of a window. Its value is a number of screen | |
198 | lines; if point comes within that many lines of the top or bottom of the | |
199 | window, Emacs recenters the window. By default, @code{scroll-margin} is | |
200 | 0. | |
201 | ||
202 | @node Horizontal Scrolling | |
203 | @section Horizontal Scrolling | |
204 | @cindex horizontal scrolling | |
205 | ||
206 | @dfn{Horizontal scrolling} means shifting all the lines sideways | |
207 | within a window---so that some of the text near the left margin is not | |
208 | displayed at all. When the text in a window is scrolled horizontally, | |
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209 | text lines are truncated rather than continued (@pxref{Line |
210 | Truncation}). Whenever a window shows truncated lines, Emacs | |
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211 | automatically updates its horizontal scrolling whenever point moves |
212 | off the left or right edge of the screen. You can also use these | |
213 | commands to do explicit horizontal scrolling. | |
214 | ||
215 | @table @kbd | |
216 | @item C-x < | |
217 | Scroll text in current window to the left (@code{scroll-left}). | |
218 | @item C-x > | |
219 | Scroll to the right (@code{scroll-right}). | |
220 | @end table | |
221 | ||
222 | @kindex C-x < | |
223 | @kindex C-x > | |
224 | @findex scroll-left | |
225 | @findex scroll-right | |
226 | The command @kbd{C-x <} (@code{scroll-left}) scrolls the selected | |
227 | window to the left by @var{n} columns with argument @var{n}. This moves | |
228 | part of the beginning of each line off the left edge of the window. | |
229 | With no argument, it scrolls by almost the full width of the window (two | |
230 | columns less, to be precise). | |
231 | ||
232 | @kbd{C-x >} (@code{scroll-right}) scrolls similarly to the right. The | |
233 | window cannot be scrolled any farther to the right once it is displayed | |
234 | normally (with each line starting at the window's left margin); | |
235 | attempting to do so has no effect. This means that you don't have to | |
236 | calculate the argument precisely for @w{@kbd{C-x >}}; any sufficiently large | |
237 | argument will restore the normal display. | |
238 | ||
239 | If you use those commands to scroll a window horizontally, that sets | |
240 | a lower bound for automatic horizontal scrolling. Automatic scrolling | |
241 | will continue to scroll the window, but never farther to the right | |
242 | than the amount you previously set by @code{scroll-left}. | |
243 | ||
244 | @vindex hscroll-margin | |
245 | The value of the variable @code{hscroll-margin} controls how close | |
246 | to the window's edges point is allowed to get before the window will | |
247 | be automatically scrolled. It is measured in columns. If the value | |
248 | is 5, then moving point within 5 columns of the edge causes horizontal | |
249 | scrolling away from that edge. | |
250 | ||
251 | @vindex hscroll-step | |
252 | The variable @code{hscroll-step} determines how many columns to | |
253 | scroll the window when point gets too close to the edge. If it's | |
254 | zero, horizontal scrolling centers point horizontally within the | |
255 | window. If it's a positive integer, it specifies the number of | |
256 | columns to scroll by. If it's a floating-point number, it specifies | |
257 | the fraction of the window's width to scroll by. The default is zero. | |
258 | ||
259 | @vindex auto-hscroll-mode | |
260 | To disable automatic horizontal scrolling, set the variable | |
261 | @code{auto-hscroll-mode} to @code{nil}. | |
262 | ||
263 | @node Follow Mode | |
264 | @section Follow Mode | |
265 | @cindex Follow mode | |
266 | @cindex mode, Follow | |
267 | @findex follow-mode | |
268 | @cindex windows, synchronizing | |
269 | @cindex synchronizing windows | |
270 | ||
271 | @dfn{Follow mode} is a minor mode that makes two windows, both | |
272 | showing the same buffer, scroll as a single tall ``virtual window.'' | |
273 | To use Follow mode, go to a frame with just one window, split it into | |
274 | two side-by-side windows using @kbd{C-x 3}, and then type @kbd{M-x | |
275 | follow-mode}. From then on, you can edit the buffer in either of the | |
276 | two windows, or scroll either one; the other window follows it. | |
277 | ||
278 | In Follow mode, if you move point outside the portion visible in one | |
279 | window and into the portion visible in the other window, that selects | |
280 | the other window---again, treating the two as if they were parts of | |
281 | one large window. | |
282 | ||
283 | To turn off Follow mode, type @kbd{M-x follow-mode} a second time. | |
284 | ||
b8f3a9e3 | 285 | @node Faces |
b18a8f7f | 286 | @section Faces: Controlling Text Display Style |
b8f3a9e3 GM |
287 | @cindex faces |
288 | ||
0015d677 RS |
289 | You can specify various styles for displaying text using |
290 | @dfn{faces}. Each face can specify various @dfn{face attributes}, | |
291 | such as the font family, the height, weight and slant of the | |
292 | characters, the foreground and background color, and underlining or | |
293 | overlining. A face does not have to specify all of these attributes; | |
294 | often it inherits most of them from another face. | |
306da12e | 295 | |
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296 | On graphical display, all the Emacs face attributes are meaningful. |
297 | On a text-only terminal, only some of them work. Some text-only | |
306da12e | 298 | terminals support inverse video, bold, and underline attributes; some |
54952612 | 299 | support colors. Text-only terminals generally do not support changing |
306da12e | 300 | the height and width or the font family. |
c1b45553 | 301 | |
b18a8f7f RS |
302 | Most major modes assign faces to the text automatically through the |
303 | work of Font Lock mode. @xref{Font Lock}, for more information about | |
304 | Font Lock mode and syntactic highlighting. You can print the current | |
305 | buffer with the highlighting that appears on your screen using the | |
306 | command @code{ps-print-buffer-with-faces}. @xref{PostScript}. | |
43d08eb9 | 307 | |
0073fd65 RS |
308 | You control the appearance of a part of the text in the buffer by |
309 | specifying the face or faces to use for it. The style of display used | |
310 | for any given character is determined by combining the attributes of | |
311 | all the applicable faces specified for that character. Any attribute | |
0ec1f115 | 312 | that isn't specified by these faces is taken from the @code{default} face, |
04d0b662 | 313 | whose attributes reflect the default settings of the frame itself. |
b8f3a9e3 GM |
314 | |
315 | Enriched mode, the mode for editing formatted text, includes several | |
0073fd65 RS |
316 | commands and menus for specifying faces for text in the buffer. |
317 | @xref{Format Faces}, for how to specify the font for text in the | |
318 | buffer. @xref{Format Colors}, for how to specify the foreground and | |
319 | background color. | |
b8f3a9e3 GM |
320 | |
321 | @cindex face colors, setting | |
322 | @findex set-face-foreground | |
323 | @findex set-face-background | |
0073fd65 RS |
324 | To alter the appearance of a face, use the customization buffer. |
325 | @xref{Face Customization}. You can also use X resources to specify | |
186e9bcc | 326 | attributes of particular faces (@pxref{Resources}). Alternatively, |
0073fd65 RS |
327 | you can change the foreground and background colors of a specific face |
328 | with @kbd{M-x set-face-foreground} and @kbd{M-x set-face-background}. | |
329 | These commands prompt in the minibuffer for a face name and a color | |
330 | name, with completion, and then set that face to use the specified | |
3ae02d92 EZ |
331 | color. Changing the colors of the @code{default} face also changes |
332 | the foreground and background colors on all frames, both existing and | |
333 | those to be created in the future. (You can also set foreground and | |
334 | background colors for the current frame only; see @ref{Frame | |
335 | Parameters}.) | |
0073fd65 | 336 | |
2a3479e2 EZ |
337 | If you want to alter the appearance of all Emacs frames, you need to |
338 | customize the frame parameters in the variable | |
339 | @code{default-frame-alist}; see @ref{Creating Frames, | |
340 | default-frame-alist}. | |
341 | ||
1b35090d RS |
342 | Emacs can correctly display variable-width fonts, but Emacs commands |
343 | that calculate width and indentation do not know how to calculate | |
344 | variable widths. This can sometimes lead to incorrect results when | |
345 | you use variable-width fonts. In particular, indentation commands can | |
346 | give inconsistent results, so we recommend you avoid variable-width | |
347 | fonts for editing program source code. Filling will sometimes make | |
348 | lines too long or too short. We plan to address these issues in | |
349 | future Emacs versions. | |
b8f3a9e3 | 350 | |
43d08eb9 RS |
351 | @node Standard Faces |
352 | @section Standard Faces | |
353 | ||
b8f3a9e3 | 354 | @findex list-faces-display |
43d08eb9 RS |
355 | To see what faces are currently defined, and what they look like, |
356 | type @kbd{M-x list-faces-display}. It's possible for a given face to | |
357 | look different in different frames; this command shows the appearance | |
93339ade CY |
358 | in the frame in which you type it. With a prefix argument, this |
359 | prompts for a regular expression, and displays only faces with names | |
360 | matching that regular expression. | |
3b91a16d | 361 | |
54952612 RS |
362 | Here are the standard faces for specifying text appearance. You can |
363 | apply them to specific text when you want the effects they produce. | |
b8f3a9e3 GM |
364 | |
365 | @table @code | |
366 | @item default | |
54952612 | 367 | This face is used for ordinary text that doesn't specify any face. |
43d08eb9 RS |
368 | @item bold |
369 | This face uses a bold variant of the default font, if it has one. | |
3b91a16d JL |
370 | It's up to you to choose a default font that has a bold variant, |
371 | if you want to use one. | |
43d08eb9 RS |
372 | @item italic |
373 | This face uses an italic variant of the default font, if it has one. | |
374 | @item bold-italic | |
375 | This face uses a bold italic variant of the default font, if it has one. | |
376 | @item underline | |
377 | This face underlines text. | |
378 | @item fixed-pitch | |
3b91a16d | 379 | This face forces use of a particular fixed-width font. |
43d08eb9 | 380 | @item variable-pitch |
3b91a16d | 381 | This face forces use of a particular variable-width font. It's |
54952612 | 382 | reasonable to customize this face to use a different variable-width font, |
3b91a16d JL |
383 | if you like, but you should not make it a fixed-width font. |
384 | @item shadow | |
385 | This face is used for making the text less noticeable than the surrounding | |
386 | ordinary text. Usually this can be achieved by using shades of gray in | |
387 | contrast with either black or white default foreground color. | |
43d08eb9 RS |
388 | @end table |
389 | ||
390 | Here's an incomplete list of faces used to highlight parts of the | |
391 | text temporarily for specific purposes. (Many other modes define | |
392 | their own faces for this purpose.) | |
393 | ||
394 | @table @code | |
395 | @item highlight | |
396 | This face is used for highlighting portions of text, in various modes. | |
397 | For example, mouse-sensitive text is highlighted using this face. | |
43d08eb9 | 398 | @item isearch |
54952612 RS |
399 | This face is used for highlighting the current Isearch match. |
400 | @item query-replace | |
401 | This face is used for highlighting the current Query Replace match. | |
43d08eb9 RS |
402 | @item lazy-highlight |
403 | This face is used for lazy highlighting of Isearch and Query Replace | |
404 | matches other than the current one. | |
405 | @item region | |
04eaab7d | 406 | This face is used for displaying a selected region (@pxref{Mark}). |
43d08eb9 RS |
407 | @item secondary-selection |
408 | This face is used for displaying a secondary X selection (@pxref{Secondary | |
409 | Selection}). | |
410 | @item trailing-whitespace | |
3b91a16d JL |
411 | The face for highlighting excess spaces and tabs at the end of a line |
412 | when @code{show-trailing-whitespace} is non-@code{nil}; see | |
413 | @ref{Useless Whitespace}. | |
43d08eb9 | 414 | @item nobreak-space |
5a7f4c1b | 415 | The face for displaying the character ``nobreak space.'' |
43d08eb9 RS |
416 | @item escape-glyph |
417 | The face for highlighting the @samp{\} or @samp{^} that indicates | |
418 | a control character. It's also used when @samp{\} indicates a | |
419 | nobreak space or nobreak (soft) hyphen. | |
43d08eb9 RS |
420 | @end table |
421 | ||
43d08eb9 RS |
422 | These faces control the appearance of parts of the Emacs frame. |
423 | They exist as faces to provide a consistent way to customize the | |
424 | appearance of these parts of the frame. | |
425 | ||
426 | @table @code | |
b8f3a9e3 | 427 | @item mode-line |
3b91a16d JL |
428 | @itemx modeline |
429 | This face is used for the mode line of the currently selected window, | |
430 | and for menu bars when toolkit menus are not used. By default, it's | |
54952612 | 431 | drawn with shadows for a ``raised'' effect on graphical displays, and |
3b91a16d JL |
432 | drawn as the inverse of the default face on non-windowed terminals. |
433 | @code{modeline} is an alias for the @code{mode-line} face, for | |
434 | compatibility with old Emacs versions. | |
b9e58bf2 EZ |
435 | @item mode-line-inactive |
436 | Like @code{mode-line}, but used for mode lines of the windows other | |
437 | than the selected one (if @code{mode-line-in-non-selected-windows} is | |
ac6875fc RS |
438 | non-@code{nil}). This face inherits from @code{mode-line}, so changes |
439 | in that face affect mode lines in all windows. | |
d545c9fd JL |
440 | @item mode-line-highlight |
441 | Like @code{highlight}, but used for portions of text on mode lines. | |
442 | @item mode-line-buffer-id | |
443 | This face is used for buffer identification parts in the mode line. | |
b8f3a9e3 | 444 | @item header-line |
54952612 RS |
445 | Similar to @code{mode-line} for a window's header line, which appears |
446 | at the top of a window just as the mode line appears at the bottom. | |
447 | Most windows do not have a header line---only some special modes, such | |
448 | Info mode, create one. | |
53abc3bf | 449 | @item vertical-border |
58f1b4d8 JL |
450 | This face is used for the vertical divider between windows. |
451 | By default this face inherits from the @code{mode-line-inactive} face | |
54952612 | 452 | on character terminals. On graphical displays the foreground color of |
58f1b4d8 JL |
453 | this face is used for the vertical line between windows without |
454 | scrollbars. | |
3094ad7a | 455 | @item minibuffer-prompt |
3b91a16d JL |
456 | @cindex @code{minibuffer-prompt} face |
457 | @vindex minibuffer-prompt-properties | |
3094ad7a | 458 | This face is used for the prompt strings displayed in the minibuffer. |
3b91a16d JL |
459 | By default, Emacs automatically adds this face to the value of |
460 | @code{minibuffer-prompt-properties}, which is a list of text | |
43d67313 RS |
461 | properties used to display the prompt text. (This variable takes |
462 | effect when you enter the minibuffer.) | |
b8f3a9e3 | 463 | @item fringe |
3b91a16d | 464 | @cindex @code{fringe} face |
b8f3a9e3 GM |
465 | The face for the fringes to the left and right of windows on graphic |
466 | displays. (The fringes are the narrow portions of the Emacs frame | |
940627fe | 467 | between the text area and the window's right and left borders.) |
43d08eb9 | 468 | @xref{Fringes}. |
b8f3a9e3 GM |
469 | @item scroll-bar |
470 | This face determines the visual appearance of the scroll bar. | |
43d08eb9 | 471 | @xref{Scroll Bars}. |
b8f3a9e3 GM |
472 | @item border |
473 | This face determines the color of the frame border. | |
474 | @item cursor | |
475 | This face determines the color of the cursor. | |
476 | @item mouse | |
477 | This face determines the color of the mouse pointer. | |
478 | @item tool-bar | |
54952612 | 479 | This face determines the color of tool bar icons. @xref{Tool Bars}. |
b8f3a9e3 | 480 | @item tooltip |
43d08eb9 | 481 | This face is used for tooltips. @xref{Tooltips}. |
b8f3a9e3 | 482 | @item menu |
9e6bb19f EZ |
483 | @cindex menu bar appearance |
484 | @cindex @code{menu} face, no effect if customized | |
485 | @cindex customization of @code{menu} face | |
486 | This face determines the colors and font of Emacs's menus. @xref{Menu | |
487 | Bars}. Setting the font of LessTif/Motif menus is currently not | |
488 | supported; attempts to set the font are ignored in this case. | |
489 | Likewise, attempts to customize this face in Emacs built with GTK and | |
461a3118 | 490 | in the MS-Windows/Mac ports are ignored by the respective GUI toolkits; |
9e6bb19f EZ |
491 | you need to use system-wide styles and options to change the |
492 | appearance of the menus. | |
b8f3a9e3 GM |
493 | @end table |
494 | ||
b8f3a9e3 GM |
495 | @node Font Lock |
496 | @section Font Lock mode | |
497 | @cindex Font Lock mode | |
498 | @cindex mode, Font Lock | |
499 | @cindex syntax highlighting and coloring | |
500 | ||
8cc11660 | 501 | Font Lock mode is a minor mode, always local to a particular buffer, |
0015d677 | 502 | which highlights (or ``fontifies'') the buffer contents according to |
8cc11660 RS |
503 | the syntax of the text you are editing. It can recognize comments and |
504 | strings in most languages; in several languages, it can also recognize | |
505 | and properly highlight various other important constructs---for | |
506 | example, names of functions being defined or reserved keywords. | |
507 | Some special modes, such as Occur mode and Info mode, have completely | |
508 | specialized ways of assigning fonts for Font Lock mode. | |
b8f3a9e3 GM |
509 | |
510 | @findex font-lock-mode | |
c4e8acbc CY |
511 | Font Lock mode is turned on by default in all modes which support it. |
512 | You can toggle font-lock for each buffer with the command @kbd{M-x | |
513 | font-lock-mode}. Using a positive argument unconditionally turns Font | |
514 | Lock mode on, and a negative or zero argument turns it off. | |
b8f3a9e3 GM |
515 | |
516 | @findex global-font-lock-mode | |
517 | @vindex global-font-lock-mode | |
c4e8acbc CY |
518 | If you do not wish Font Lock mode to be turned on by default, |
519 | customize the variable @code{global-font-lock-mode} using the Customize | |
520 | interface (@pxref{Easy Customization}), or use the function | |
d239287a | 521 | @code{global-font-lock-mode} in your @file{.emacs} file, like this: |
b8f3a9e3 GM |
522 | |
523 | @example | |
c4e8acbc | 524 | (global-font-lock-mode 0) |
b8f3a9e3 GM |
525 | @end example |
526 | ||
43d67313 RS |
527 | @noindent |
528 | This variable, like all the variables that control Font Lock mode, | |
529 | take effect whenever fontification is done; that is, potentially at | |
530 | any time. | |
531 | ||
c4e8acbc | 532 | @findex turn-on-font-lock |
54952612 RS |
533 | If you have disabled Global Font Lock mode, you can still enable Font |
534 | Lock for specific major modes by adding the function | |
c4e8acbc CY |
535 | @code{turn-on-font-lock} to the mode hooks (@pxref{Hooks}). For |
536 | example, to enable Font Lock mode for editing C files, you can do this: | |
537 | ||
538 | @example | |
539 | (add-hook 'c-mode-hook 'turn-on-font-lock) | |
540 | @end example | |
0015d677 | 541 | |
b8f3a9e3 GM |
542 | Font Lock mode uses several specifically named faces to do its job, |
543 | including @code{font-lock-string-face}, @code{font-lock-comment-face}, | |
54952612 RS |
544 | and others. The easiest way to find them all is to use @kbd{M-x |
545 | customize-group @key{RET} font-lock-faces @key{RET}}. You can then | |
546 | use that customization buffer to customize the appearance of these | |
547 | faces. @xref{Face Customization}. | |
b8f3a9e3 | 548 | |
54952612 RS |
549 | You can also customize these faces using @kbd{M-x |
550 | set-face-foreground} or @kbd{M-x set-face-background}. @xref{Faces}. | |
b8f3a9e3 | 551 | |
b8f3a9e3 GM |
552 | @vindex font-lock-maximum-decoration |
553 | The variable @code{font-lock-maximum-decoration} specifies the | |
554 | preferred level of fontification, for modes that provide multiple | |
555 | levels. Level 1 is the least amount of fontification; some modes | |
556 | support levels as high as 3. The normal default is ``as high as | |
557 | possible.'' You can specify an integer, which applies to all modes, or | |
558 | you can specify different numbers for particular major modes; for | |
559 | example, to use level 1 for C/C++ modes, and the default level | |
560 | otherwise, use this: | |
561 | ||
562 | @example | |
563 | (setq font-lock-maximum-decoration | |
564 | '((c-mode . 1) (c++-mode . 1))) | |
565 | @end example | |
566 | ||
567 | @vindex font-lock-maximum-size | |
568 | Fontification can be too slow for large buffers, so you can suppress | |
54952612 RS |
569 | it for buffers above a certain size. The variable |
570 | @code{font-lock-maximum-size} specifies a buffer size, beyond which | |
571 | buffer fontification is suppressed. | |
b8f3a9e3 GM |
572 | |
573 | @c @w is used below to prevent a bad page-break. | |
574 | @vindex font-lock-beginning-of-syntax-function | |
e07e854d EZ |
575 | @cindex incorrect fontification |
576 | @cindex parenthesis in column zero and fontification | |
577 | @cindex brace in column zero and fontification | |
b8f3a9e3 GM |
578 | Comment and string fontification (or ``syntactic'' fontification) |
579 | relies on analysis of the syntactic structure of the buffer text. For | |
174862cf RS |
580 | the sake of speed, some modes, including Lisp mode, rely on a special |
581 | convention: an open-parenthesis or open-brace in the leftmost column | |
582 | always defines the @w{beginning} of a defun, and is thus always | |
583 | outside any string or comment. (@xref{Left Margin Paren}.) If you | |
584 | don't follow this convention, Font Lock mode can misfontify the text | |
585 | that follows an open-parenthesis or open-brace in the leftmost column | |
586 | that is inside a string or comment. | |
b8f3a9e3 | 587 | |
6bb2ed9b | 588 | @cindex slow display during scrolling |
b8f3a9e3 GM |
589 | The variable @code{font-lock-beginning-of-syntax-function} (always |
590 | buffer-local) specifies how Font Lock mode can find a position | |
591 | guaranteed to be outside any comment or string. In modes which use the | |
592 | leftmost column parenthesis convention, the default value of the variable | |
593 | is @code{beginning-of-defun}---that tells Font Lock mode to use the | |
594 | convention. If you set this variable to @code{nil}, Font Lock no longer | |
595 | relies on the convention. This avoids incorrect results, but the price | |
596 | is that, in some cases, fontification for a changed text must rescan | |
6bb2ed9b EZ |
597 | buffer text from the beginning of the buffer. This can considerably |
598 | slow down redisplay while scrolling, particularly if you are close to | |
599 | the end of a large buffer. | |
b8f3a9e3 GM |
600 | |
601 | @findex font-lock-add-keywords | |
602 | Font Lock highlighting patterns already exist for many modes, but you | |
603 | may want to fontify additional patterns. You can use the function | |
604 | @code{font-lock-add-keywords}, to add your own highlighting patterns for | |
605 | a particular mode. For example, to highlight @samp{FIXME:} words in C | |
606 | comments, use this: | |
607 | ||
608 | @example | |
a152877d SM |
609 | (add-hook 'c-mode-hook |
610 | (lambda () | |
611 | (font-lock-add-keywords nil | |
612 | '(("\\<\\(FIXME\\):" 1 font-lock-warning-face t))))) | |
b8f3a9e3 GM |
613 | @end example |
614 | ||
4063fff3 EZ |
615 | @findex font-lock-remove-keywords |
616 | To remove keywords from the font-lock highlighting patterns, use the | |
cd77ce13 | 617 | function @code{font-lock-remove-keywords}. @xref{Search-based |
09139bc5 LT |
618 | Fontification,,, elisp, The Emacs Lisp Reference Manual}, for |
619 | documentation of the format of this list. | |
4063fff3 | 620 | |
3be9b0ca EZ |
621 | @cindex just-in-time (JIT) font-lock |
622 | @cindex background syntax highlighting | |
623 | Fontifying large buffers can take a long time. To avoid large | |
624 | delays when a file is visited, Emacs fontifies only the visible | |
625 | portion of a buffer. As you scroll through the buffer, each portion | |
626 | that becomes visible is fontified as soon as it is displayed. The | |
627 | parts of the buffer that are not displayed are fontified | |
de4a4c41 | 628 | ``stealthily,'' in the background, i.e.@: when Emacs is idle. You can |
bdc3b3be RS |
629 | control this background fontification, also called @dfn{Just-In-Time} |
630 | (or @dfn{JIT}) Lock, by customizing variables in the customization | |
631 | group @samp{jit-lock}. @xref{Specific Customization}. | |
3be9b0ca | 632 | |
b8f3a9e3 | 633 | @node Highlight Interactively |
54952612 | 634 | @section Interactive Highlighting |
b8f3a9e3 GM |
635 | @cindex highlighting by matching |
636 | @cindex interactive highlighting | |
54952612 | 637 | @cindex Highlight Changes mode |
b8f3a9e3 | 638 | |
54952612 RS |
639 | @findex highlight-changes-mode |
640 | Use @kbd{M-x highlight-changes-mode} to enable (or disable) | |
641 | Highlight Changes mode, a minor mode that uses faces (colors, | |
642 | typically) to indicate which parts of the buffer were changed most | |
643 | recently. | |
b8f3a9e3 | 644 | |
54952612 | 645 | @cindex Hi Lock mode |
b8f3a9e3 | 646 | @findex hi-lock-mode |
3173ce7e RS |
647 | Hi Lock mode highlights text that matches regular expressions you |
648 | specify. For example, you might wish to see all the references to a | |
649 | certain variable in a program source file, highlight certain parts in | |
650 | a voluminous output of some program, or make certain names stand out | |
651 | in an article. Use the @kbd{M-x hi-lock-mode} command to enable (or | |
652 | disable) Hi Lock mode. To enable Hi Lock mode for all buffers, use | |
653 | @kbd{M-x global-hi-lock-mode} or place @code{(global-hi-lock-mode 1)} | |
654 | in your @file{.emacs} file. | |
54952612 RS |
655 | |
656 | Hi Lock mode works like Font Lock mode (@pxref{Font Lock}), except | |
657 | that you specify explicitly the regular expressions to highlight. You | |
658 | control them with these commands: | |
b8f3a9e3 GM |
659 | |
660 | @table @kbd | |
661 | @item C-x w h @var{regexp} @key{RET} @var{face} @key{RET} | |
662 | @kindex C-x w h | |
663 | @findex highlight-regexp | |
cedf175b | 664 | Highlight text that matches @var{regexp} using face @var{face} |
54952612 RS |
665 | (@code{highlight-regexp}). The highlighting will remain as long as |
666 | the buffer is loaded. For example, to highlight all occurrences of | |
667 | the word ``whim'' using the default face (a yellow background) | |
668 | @kbd{C-x w h whim @key{RET} @key{RET}}. Any face can be used for | |
669 | highlighting, Hi Lock provides several of its own and these are | |
670 | pre-loaded into a history list. While being prompted for a face use | |
671 | @kbd{M-p} and @kbd{M-n} to cycle through them. | |
672 | ||
673 | You can use this command multiple times, specifying various regular | |
674 | expressions to highlight in different ways. | |
b8f3a9e3 GM |
675 | |
676 | @item C-x w r @var{regexp} @key{RET} | |
677 | @kindex C-x w r | |
678 | @findex unhighlight-regexp | |
630acdcc | 679 | Unhighlight @var{regexp} (@code{unhighlight-regexp}). |
54952612 RS |
680 | |
681 | If you invoke this from the menu, you select the expression to | |
682 | unhighlight from a list. If you invoke this from the keyboard, you | |
683 | use the minibuffer. It will show the most recently added regular | |
684 | expression; use @kbd{M-p} to show the next older expression and | |
685 | @kbd{M-n} to select the next newer expression. (You can also type the | |
686 | expression by hand, with completion.) When the expression you want to | |
687 | unhighlight appears in the minibuffer, press @kbd{@key{RET}} to exit | |
688 | the minibuffer and unhighlight it. | |
b8f3a9e3 GM |
689 | |
690 | @item C-x w l @var{regexp} @key{RET} @var{face} @key{RET} | |
691 | @kindex C-x w l | |
692 | @findex highlight-lines-matching-regexp | |
693 | @cindex lines, highlighting | |
694 | @cindex highlighting lines of text | |
04d0b662 | 695 | Highlight entire lines containing a match for @var{regexp}, using face |
b8f3a9e3 GM |
696 | @var{face} (@code{highlight-lines-matching-regexp}). |
697 | ||
698 | @item C-x w b | |
699 | @kindex C-x w b | |
700 | @findex hi-lock-write-interactive-patterns | |
701 | Insert all the current highlighting regexp/face pairs into the buffer | |
702 | at point, with comment delimiters to prevent them from changing your | |
54952612 RS |
703 | program. (This key binding runs the |
704 | @code{hi-lock-write-interactive-patterns} command.) | |
b8f3a9e3 | 705 | |
3173ce7e RS |
706 | These patterns are extracted from the comments, if appropriate, if you |
707 | invoke @kbd{M-x hi-lock-find-patterns}, or if you visit the file while | |
708 | Hi Lock mode is enabled (since that runs @code{hi-lock-find-patterns}). | |
b8f3a9e3 GM |
709 | |
710 | @item C-x w i | |
711 | @kindex C-x w i | |
712 | @findex hi-lock-find-patterns | |
3173ce7e RS |
713 | Extract regexp/face pairs from comments in the current buffer |
714 | (@code{hi-lock-find-patterns}). Thus, you can enter patterns | |
715 | interactively with @code{highlight-regexp}, store them into the file | |
716 | with @code{hi-lock-write-interactive-patterns}, edit them (perhaps | |
cedf175b | 717 | including different faces for different parenthesized parts of the |
3173ce7e RS |
718 | match), and finally use this command (@code{hi-lock-find-patterns}) to |
719 | have Hi Lock highlight the edited patterns. | |
b8f3a9e3 | 720 | |
3173ce7e | 721 | @vindex hi-lock-file-patterns-policy |
d439bcd8 CY |
722 | The variable @code{hi-lock-file-patterns-policy} controls whether Hi |
723 | Lock mode should automatically extract and highlight patterns found in | |
724 | a file when it is visited. Its value can be @code{nil} (never | |
725 | highlight), @code{t} (highlight the patterns), @code{ask} (query the | |
726 | user), or a function. If it is a function, | |
3173ce7e | 727 | @code{hi-lock-find-patterns} calls it with the patterns as argument; |
d439bcd8 CY |
728 | if the function returns non-@code{nil}, the patterns are used. The |
729 | default is @code{nil}. Note that patterns are always highlighted if | |
730 | you call @code{hi-lock-find-patterns} directly, regardless of the | |
731 | value of this variable. | |
3173ce7e RS |
732 | |
733 | @vindex hi-lock-exclude-modes | |
734 | Also, @code{hi-lock-find-patterns} does nothing if the current major | |
735 | mode's symbol is a member of the list @code{hi-lock-exclude-modes}. | |
b8f3a9e3 GM |
736 | @end table |
737 | ||
fad78d58 RS |
738 | @node Fringes |
739 | @section Window Fringes | |
740 | @cindex fringes | |
741 | ||
742 | On a graphical display, each Emacs window normally has narrow | |
743 | @dfn{fringes} on the left and right edges. The fringes display | |
744 | indications about the text in the window. | |
745 | ||
746 | The most common use of the fringes is to indicate a continuation | |
747 | line, when one line of text is split into multiple lines on the | |
748 | screen. The left fringe shows a curving arrow for each screen line | |
749 | except the first, indicating that ``this is not the real beginning.'' | |
750 | The right fringe shows a curving arrow for each screen line except the | |
751 | last, indicating that ``this is not the real end.'' | |
752 | ||
566da2e7 | 753 | The fringes indicate line truncation with short horizontal arrows |
fad78d58 | 754 | meaning ``there's more text on this line which is scrolled |
566da2e7 EZ |
755 | horizontally out of view;'' clicking the mouse on one of the arrows |
756 | scrolls the display horizontally in the direction of the arrow. The | |
d239287a | 757 | fringes can also indicate other things, such as empty lines, or where a |
566da2e7 | 758 | program you are debugging is executing (@pxref{Debuggers}). |
fad78d58 RS |
759 | |
760 | @findex set-fringe-style | |
761 | @findex fringe-mode | |
762 | You can enable and disable the fringes for all frames using | |
763 | @kbd{M-x fringe-mode}. To enable and disable the fringes | |
764 | for the selected frame, use @kbd{M-x set-fringe-style}. | |
765 | ||
9d2908a6 RS |
766 | @node Displaying Boundaries |
767 | @section Displaying Boundaries | |
768 | ||
769 | @vindex indicate-buffer-boundaries | |
770 | On a graphical display, Emacs can indicate the buffer boundaries in | |
771 | the fringes. It indicates the first line and the last line with | |
772 | angle images in the fringes. This can be combined with up and down | |
773 | arrow images which say whether it is possible to scroll the window up | |
774 | and down. | |
775 | ||
776 | The buffer-local variable @code{indicate-buffer-boundaries} controls | |
777 | how the buffer boundaries and window scrolling is indicated in the | |
778 | fringes. If the value is @code{left} or @code{right}, both angle and | |
779 | arrow bitmaps are displayed in the left or right fringe, respectively. | |
780 | ||
781 | If value is an alist, each element @code{(@var{indicator} . | |
782 | @var{position})} specifies the position of one of the indicators. | |
783 | The @var{indicator} must be one of @code{top}, @code{bottom}, | |
784 | @code{up}, @code{down}, or @code{t} which specifies the default | |
785 | position for the indicators not present in the alist. | |
786 | The @var{position} is one of @code{left}, @code{right}, or @code{nil} | |
787 | which specifies not to show this indicator. | |
788 | ||
789 | For example, @code{((top . left) (t . right))} places the top angle | |
790 | bitmap in left fringe, the bottom angle bitmap in right fringe, and | |
791 | both arrow bitmaps in right fringe. To show just the angle bitmaps in | |
792 | the left fringe, but no arrow bitmaps, use @code{((top . left) | |
793 | (bottom . left))}. | |
794 | ||
795 | @vindex default-indicate-buffer-boundaries | |
796 | The value of the variable @code{default-indicate-buffer-boundaries} | |
797 | is the default value for @code{indicate-buffer-boundaries} in buffers | |
798 | that do not override it. | |
799 | ||
fad78d58 RS |
800 | @node Useless Whitespace |
801 | @section Useless Whitespace | |
802 | ||
803 | @cindex trailing whitespace | |
804 | @cindex whitespace, trailing | |
805 | @vindex show-trailing-whitespace | |
806 | It is easy to leave unnecessary spaces at the end of a line, or | |
807 | empty lines at the end of a file, without realizing it. In most | |
808 | cases, this @dfn{trailing whitespace} has no effect, but there are | |
54952612 RS |
809 | special circumstances where it matters. It can also be a nuisance |
810 | that the line has ``changed,'' when the change is just spaces added or | |
811 | removed at the end. | |
fad78d58 RS |
812 | |
813 | You can make trailing whitespace at the end of a line visible on the | |
814 | screen by setting the buffer-local variable | |
815 | @code{show-trailing-whitespace} to @code{t}. Then Emacs displays | |
816 | trailing whitespace in the face @code{trailing-whitespace}. | |
817 | ||
818 | This feature does not apply when point is at the end of the line | |
819 | containing the whitespace. Strictly speaking, that is ``trailing | |
820 | whitespace'' nonetheless, but displaying it specially in that case | |
821 | looks ugly while you are typing in new text. In this special case, | |
822 | the location of point is enough to show you that the spaces are | |
823 | present. | |
824 | ||
825 | @findex delete-trailing-whitespace | |
826 | To delete all trailing whitespace within the current buffer's | |
827 | accessible portion (@pxref{Narrowing}), type @kbd{M-x | |
828 | delete-trailing-whitespace @key{RET}}. (This command does not remove | |
829 | the form-feed characters.) | |
830 | ||
23e3383d | 831 | @vindex indicate-empty-lines |
fad78d58 | 832 | @vindex default-indicate-empty-lines |
877db12e RS |
833 | @cindex unused lines |
834 | @cindex fringes, and unused line indication | |
835 | Emacs can indicate unused lines at the end of the window with a | |
836 | small image in the left fringe (@pxref{Fringes}). The image appears | |
837 | for window lines that do not correspond to any buffer text. Blank | |
838 | lines at the end of the buffer then stand out because they do not have | |
839 | this image in the fringe. | |
840 | ||
841 | To enable this feature, set the buffer-local variable | |
23e3383d | 842 | @code{indicate-empty-lines} to a non-@code{nil} value. The default |
877db12e | 843 | value of this variable is controlled by the variable |
23e3383d | 844 | @code{default-indicate-empty-lines}; by setting that variable, you |
877db12e | 845 | can enable or disable this feature for all new buffers. (This feature |
54952612 | 846 | currently doesn't work on text-only terminals.) |
fad78d58 | 847 | |
6bf7aab6 DL |
848 | @node Selective Display |
849 | @section Selective Display | |
4946337d | 850 | @cindex selective display |
6bf7aab6 DL |
851 | @findex set-selective-display |
852 | @kindex C-x $ | |
853 | ||
854 | Emacs has the ability to hide lines indented more than a certain number | |
855 | of columns (you specify how many columns). You can use this to get an | |
856 | overview of a part of a program. | |
857 | ||
d239287a LT |
858 | To hide lines in the current buffer, type @kbd{C-x $} |
859 | (@code{set-selective-display}) with a numeric argument @var{n}. Then | |
860 | lines with at least @var{n} columns of indentation disappear from the | |
861 | screen. The only indication of their presence is that three dots | |
862 | (@samp{@dots{}}) appear at the end of each visible line that is | |
863 | followed by one or more hidden ones. | |
6bf7aab6 DL |
864 | |
865 | The commands @kbd{C-n} and @kbd{C-p} move across the hidden lines as | |
866 | if they were not there. | |
867 | ||
868 | The hidden lines are still present in the buffer, and most editing | |
869 | commands see them as usual, so you may find point in the middle of the | |
870 | hidden text. When this happens, the cursor appears at the end of the | |
871 | previous line, after the three dots. If point is at the end of the | |
872 | visible line, before the newline that ends it, the cursor appears before | |
873 | the three dots. | |
874 | ||
875 | To make all lines visible again, type @kbd{C-x $} with no argument. | |
876 | ||
877 | @vindex selective-display-ellipses | |
878 | If you set the variable @code{selective-display-ellipses} to | |
879 | @code{nil}, the three dots do not appear at the end of a line that | |
880 | precedes hidden lines. Then there is no visible indication of the | |
881 | hidden lines. This variable becomes local automatically when set. | |
882 | ||
0015d677 RS |
883 | See also @ref{Outline Mode} for another way to hide part of |
884 | the text in a buffer. | |
885 | ||
6bf7aab6 DL |
886 | @node Optional Mode Line |
887 | @section Optional Mode Line Features | |
888 | ||
b213b767 LK |
889 | @cindex buffer size display |
890 | @cindex display of buffer size | |
891 | @findex size-indication-mode | |
892 | The buffer percentage @var{pos} indicates the percentage of the | |
893 | buffer above the top of the window. You can additionally display the | |
894 | size of the buffer by typing @kbd{M-x size-indication-mode} to turn on | |
895 | Size Indication mode. The size will be displayed immediately | |
896 | following the buffer percentage like this: | |
897 | ||
898 | @example | |
899 | @var{POS} of @var{SIZE} | |
900 | @end example | |
901 | ||
902 | @noindent | |
903 | Here @var{SIZE} is the human readable representation of the number of | |
904 | characters in the buffer, which means that @samp{k} for 10^3, @samp{M} | |
905 | for 10^6, @samp{G} for 10^9, etc., are used to abbreviate. | |
906 | ||
907 | @cindex narrowing, and buffer size display | |
908 | If you have narrowed the buffer (@pxref{Narrowing}), the size of the | |
909 | accessible part of the buffer is shown. | |
910 | ||
e598186c RS |
911 | @cindex line number display |
912 | @cindex display of line number | |
6bf7aab6 DL |
913 | @findex line-number-mode |
914 | The current line number of point appears in the mode line when Line | |
915 | Number mode is enabled. Use the command @kbd{M-x line-number-mode} to | |
916 | turn this mode on and off; normally it is on. The line number appears | |
b213b767 | 917 | after the buffer percentage @var{pos}, with the letter @samp{L} to |
79199dd2 AM |
918 | indicate what it is. |
919 | ||
920 | @cindex Column Number mode | |
921 | @cindex mode, Column Number | |
922 | @findex column-number-mode | |
923 | Similarly, you can display the current column number by turning on | |
924 | Column number mode with @kbd{M-x column-number-mode}. The column | |
925 | number is indicated by the letter @samp{C}. However, when both of | |
926 | these modes are enabled, the line and column numbers are displayed in | |
927 | parentheses, the line number first, rather than with @samp{L} and | |
928 | @samp{C}. For example: @samp{(561,2)}. @xref{Minor Modes}, for more | |
929 | information about minor modes and about how to use these commands. | |
6bf7aab6 | 930 | |
43f971ab EZ |
931 | @cindex narrowing, and line number display |
932 | If you have narrowed the buffer (@pxref{Narrowing}), the displayed | |
933 | line number is relative to the accessible portion of the buffer. | |
54952612 RS |
934 | Thus, it isn't suitable as an argument to @code{goto-line}. (Use |
935 | @code{what-line} command to see the line number relative to the whole | |
936 | file.) | |
43f971ab | 937 | |
6bf7aab6 DL |
938 | @vindex line-number-display-limit |
939 | If the buffer is very large (larger than the value of | |
940 | @code{line-number-display-limit}), then the line number doesn't appear. | |
941 | Emacs doesn't compute the line number when the buffer is large, because | |
43f971ab EZ |
942 | that would be too slow. Set it to @code{nil} to remove the limit. |
943 | ||
944 | @vindex line-number-display-limit-width | |
945 | Line-number computation can also be slow if the lines in the buffer | |
946 | are too long. For this reason, Emacs normally doesn't display line | |
947 | numbers if the average width, in characters, of lines near point is | |
948 | larger than the value of the variable | |
949 | @code{line-number-display-limit-width}. The default value is 200 | |
950 | characters. | |
6bf7aab6 | 951 | |
6bf7aab6 DL |
952 | @findex display-time |
953 | @cindex time (on mode line) | |
954 | Emacs can optionally display the time and system load in all mode | |
4f00b8c1 DL |
955 | lines. To enable this feature, type @kbd{M-x display-time} or customize |
956 | the option @code{display-time-mode}. The information added to the mode | |
957 | line usually appears after the buffer name, before the mode names and | |
958 | their parentheses. It looks like this: | |
6bf7aab6 DL |
959 | |
960 | @example | |
961 | @var{hh}:@var{mm}pm @var{l.ll} | |
962 | @end example | |
963 | ||
964 | @noindent | |
965 | @vindex display-time-24hr-format | |
966 | Here @var{hh} and @var{mm} are the hour and minute, followed always by | |
967 | @samp{am} or @samp{pm}. @var{l.ll} is the average number of running | |
968 | processes in the whole system recently. (Some fields may be missing if | |
969 | your operating system cannot support them.) If you prefer time display | |
970 | in 24-hour format, set the variable @code{display-time-24hr-format} | |
971 | to @code{t}. | |
972 | ||
973 | @cindex mail (on mode line) | |
72bd7b7b DL |
974 | @vindex display-time-use-mail-icon |
975 | @vindex display-time-mail-face | |
fad78d58 RS |
976 | @vindex display-time-mail-file |
977 | @vindex display-time-mail-directory | |
6bf7aab6 | 978 | The word @samp{Mail} appears after the load level if there is mail |
72bd7b7b DL |
979 | for you that you have not read yet. On a graphical display you can use |
980 | an icon instead of @samp{Mail} by customizing | |
981 | @code{display-time-use-mail-icon}; this may save some space on the mode | |
982 | line. You can customize @code{display-time-mail-face} to make the mail | |
fad78d58 RS |
983 | indicator prominent. Use @code{display-time-mail-file} to specify |
984 | the mail file to check, or set @code{display-time-mail-directory} | |
985 | to specify the directory to check for incoming mail (any nonempty regular | |
986 | file in the directory is considered as ``newly arrived mail''). | |
6bf7aab6 | 987 | |
47d7776c | 988 | @cindex mode line, 3D appearance |
bd3ead08 EZ |
989 | @cindex attributes of mode line, changing |
990 | @cindex non-integral number of lines in a window | |
04d0b662 RS |
991 | By default, the mode line is drawn on graphics displays with |
992 | 3D-style highlighting, like that of a button when it is not being | |
993 | pressed. If you don't like this effect, you can disable the 3D | |
994 | highlighting of the mode line, by customizing the attributes of the | |
54952612 | 995 | @code{mode-line} face. @xref{Face Customization}. |
bd3ead08 | 996 | |
b9e58bf2 | 997 | @cindex non-selected windows, mode line appearance |
ac6875fc | 998 | By default, the mode line of nonselected windows is displayed in a |
1c9f5f23 | 999 | different face, called @code{mode-line-inactive}. Only the selected |
ac6875fc RS |
1000 | window is displayed in the @code{mode-line} face. This helps show |
1001 | which window is selected. When the minibuffer is selected, since | |
1002 | it has no mode line, the window from which you activated the minibuffer | |
1003 | has its mode line displayed using @code{mode-line}; as a result, | |
1004 | ordinary entry to the minibuffer does not change any mode lines. | |
1005 | ||
1006 | @vindex mode-line-in-non-selected-windows | |
1007 | You can disable use of @code{mode-line-inactive} by setting variable | |
1c9f5f23 KS |
1008 | @code{mode-line-in-non-selected-windows} to @code{nil}; then all mode |
1009 | lines are displayed in the @code{mode-line} face. | |
b9e58bf2 | 1010 | |
589a3f9f RS |
1011 | @vindex eol-mnemonic-unix |
1012 | @vindex eol-mnemonic-dos | |
1013 | @vindex eol-mnemonic-mac | |
1014 | @vindex eol-mnemonic-undecided | |
1015 | You can customize the mode line display for each of the end-of-line | |
1016 | formats by setting each of the variables @code{eol-mnemonic-unix}, | |
1017 | @code{eol-mnemonic-dos}, @code{eol-mnemonic-mac}, and | |
54952612 | 1018 | @code{eol-mnemonic-undecided} to the strings you prefer. |
589a3f9f | 1019 | |
6bf7aab6 DL |
1020 | @node Text Display |
1021 | @section How Text Is Displayed | |
1022 | @cindex characters (in text) | |
1023 | ||
76dd3692 | 1024 | @acronym{ASCII} printing characters (octal codes 040 through 0176) in Emacs |
13b9ee95 | 1025 | buffers are displayed with their graphics, as are non-ASCII multibyte |
6bf7aab6 DL |
1026 | printing characters (octal codes above 0400). |
1027 | ||
76dd3692 | 1028 | Some @acronym{ASCII} control characters are displayed in special ways. The |
6bf7aab6 DL |
1029 | newline character (octal code 012) is displayed by starting a new line. |
1030 | The tab character (octal code 011) is displayed by moving to the next | |
1031 | tab stop column (normally every 8 columns). | |
1032 | ||
76dd3692 | 1033 | Other @acronym{ASCII} control characters are normally displayed as a caret |
6bf7aab6 | 1034 | (@samp{^}) followed by the non-control version of the character; thus, |
54952612 RS |
1035 | control-A is displayed as @samp{^A}. The caret appears in face |
1036 | @code{escape-glyph}. | |
1037 | ||
1038 | Non-@acronym{ASCII} characters 0200 through 0237 (octal) are | |
1039 | displayed with octal escape sequences; thus, character code 0230 | |
1040 | (octal) is displayed as @samp{\230}. The backslash appears in face | |
1041 | @code{escape-glyph}. | |
1042 | ||
1043 | @vindex ctl-arrow | |
1044 | If the variable @code{ctl-arrow} is @code{nil}, control characters in | |
1045 | the buffer are displayed with octal escape sequences, except for newline | |
1046 | and tab. Altering the value of @code{ctl-arrow} makes it local to the | |
1047 | current buffer; until that time, the default value is in effect. The | |
1048 | default is initially @code{t}. | |
1049 | ||
1050 | The display of character codes 0240 through 0377 (octal) may be | |
1051 | either as escape sequences or as graphics. They do not normally occur | |
1052 | in multibyte buffers, but if they do, they are displayed as Latin-1 | |
1053 | graphics. In unibyte mode, if you enable European display they are | |
1054 | displayed using their graphics (assuming your terminal supports them), | |
662286c3 | 1055 | otherwise as escape sequences. @xref{Unibyte Mode}. |
6bf7aab6 | 1056 | |
470a11a3 | 1057 | @vindex nobreak-char-display |
367aa52c RS |
1058 | @cindex no-break space, display |
1059 | @cindex no-break hyphen, display | |
1060 | @cindex soft hyphen, display | |
470a11a3 RS |
1061 | Some character sets define ``no-break'' versions of the space and |
1062 | hyphen characters, which are used where a line should not be broken. | |
1063 | Emacs normally displays these characters with special faces | |
1064 | (respectively, @code{nobreak-space} and @code{escape-glyph}) to | |
1065 | distinguish them from ordinary spaces and hyphens. You can turn off | |
1066 | this feature by setting the variable @code{nobreak-char-display} to | |
1067 | @code{nil}. If you set the variable to any other value, that means to | |
1068 | prefix these characters with an escape character. | |
b5cced4b | 1069 | |
54952612 RS |
1070 | @vindex tab-width |
1071 | @vindex default-tab-width | |
1072 | Normally, a tab character in the buffer is displayed as whitespace which | |
1073 | extends to the next display tab stop position, and display tab stops come | |
1074 | at intervals equal to eight spaces. The number of spaces per tab is | |
1075 | controlled by the variable @code{tab-width}, which is made local by | |
1076 | changing it. Note that how the tab character | |
1077 | in the buffer is displayed has nothing to do with the definition of | |
1078 | @key{TAB} as a command. The variable @code{tab-width} must have an | |
1079 | integer value between 1 and 1000, inclusive. The variable | |
1080 | @code{default-tab-width} controls the default value of this variable | |
1081 | for buffers where you have not set it locally. | |
1082 | ||
1083 | You can customize the way any particular character code is displayed | |
1084 | by means of a display table. @xref{Display Tables,, Display Tables, | |
1085 | elisp, The Emacs Lisp Reference Manual}. | |
1086 | ||
0015d677 RS |
1087 | @node Cursor Display |
1088 | @section Displaying the Cursor | |
1089 | ||
1090 | @findex blink-cursor-mode | |
1091 | @vindex blink-cursor-alist | |
1092 | @cindex cursor, locating visually | |
1093 | @cindex cursor, blinking | |
1094 | You can customize the cursor's color, and whether it blinks, using | |
1095 | the @code{cursor} Custom group (@pxref{Easy Customization}). On | |
098199b1 | 1096 | a graphical display, the command @kbd{M-x blink-cursor-mode} enables |
0015d677 RS |
1097 | or disables the blinking of the cursor. (On text terminals, the |
1098 | terminal itself blinks the cursor, and Emacs has no control over it.) | |
1099 | You can control how the cursor appears when it blinks off by setting | |
1100 | the variable @code{blink-cursor-alist}. | |
1101 | ||
468160b7 SM |
1102 | @vindex visible-cursor |
1103 | Some text terminals offer two different cursors: the normal cursor | |
1104 | and the very visible cursor, where the latter may be e.g. bigger or | |
43d67313 RS |
1105 | blinking. By default Emacs uses the very visible cursor, and switches |
1106 | to it when you start or resume Emacs. If the variable | |
1107 | @code{visible-cursor} is @code{nil} when Emacs starts or resumes, it | |
1108 | doesn't switch, so it uses the normal cursor. | |
468160b7 | 1109 | |
0015d677 RS |
1110 | @cindex cursor in non-selected windows |
1111 | @vindex cursor-in-non-selected-windows | |
93870ce2 RS |
1112 | Normally, the cursor appears in non-selected windows without |
1113 | blinking, with the same appearance as when the blinking cursor blinks | |
5a7f4c1b | 1114 | ``off.'' For a box cursor, this is a hollow box; for a bar cursor, |
0015d677 | 1115 | this is a thinner bar. To turn off cursors in non-selected windows, |
93870ce2 RS |
1116 | customize the variable @code{cursor-in-non-selected-windows} and |
1117 | assign it a @code{nil} value. | |
0015d677 RS |
1118 | |
1119 | @vindex x-stretch-cursor | |
1120 | @cindex wide block cursor | |
098199b1 | 1121 | On graphical displays, Emacs can optionally draw the block cursor |
0015d677 RS |
1122 | as wide as the character under the cursor---for example, if the cursor |
1123 | is on a tab character, it would cover the full width occupied by that | |
1124 | tab character. To enable this feature, set the variable | |
1125 | @code{x-stretch-cursor} to a non-@code{nil} value. | |
1126 | ||
1127 | @findex hl-line-mode | |
1128 | @findex global-hl-line-mode | |
1129 | @cindex highlight current line | |
54952612 RS |
1130 | To make the cursor even more visible, you can use HL Line mode, a |
1131 | minor mode that highlights the line containing point. Use @kbd{M-x | |
0015d677 RS |
1132 | hl-line-mode} to enable or disable it in the current buffer. @kbd{M-x |
1133 | global-hl-line-mode} enables or disables the same mode globally. | |
1134 | ||
9d2908a6 RS |
1135 | @node Line Truncation |
1136 | @section Truncation of Lines | |
0015d677 RS |
1137 | |
1138 | @cindex truncation | |
1139 | @cindex line truncation, and fringes | |
1140 | As an alternative to continuation, Emacs can display long lines by | |
1141 | @dfn{truncation}. This means that all the characters that do not fit | |
1142 | in the width of the screen or window do not appear at all. On | |
54952612 RS |
1143 | graphical displays, a small straight arrow in the fringe indicates |
1144 | truncation at either end of the line. On text-only terminals, @samp{$} | |
0015d677 RS |
1145 | appears in the first column when there is text truncated to the left, |
1146 | and in the last column when there is text truncated to the right. | |
1147 | ||
1148 | @vindex truncate-lines | |
1149 | @findex toggle-truncate-lines | |
1150 | Horizontal scrolling automatically causes line truncation | |
1151 | (@pxref{Horizontal Scrolling}). You can explicitly enable line | |
1152 | truncation for a particular buffer with the command @kbd{M-x | |
1153 | toggle-truncate-lines}. This works by locally changing the variable | |
1154 | @code{truncate-lines}. If that variable is non-@code{nil}, long lines | |
1155 | are truncated; if it is @code{nil}, they are continued onto multiple | |
1156 | screen lines. Setting the variable @code{truncate-lines} in any way | |
1157 | makes it local to the current buffer; until that time, the default | |
1158 | value is in effect. The default value is normally @code{nil}. | |
6bf7aab6 DL |
1159 | |
1160 | @c @vindex truncate-partial-width-windows @c Idx entry is in Split Windows. | |
1161 | If the variable @code{truncate-partial-width-windows} is | |
1162 | non-@code{nil}, it forces truncation rather than continuation in any | |
1163 | window less than the full width of the screen or frame, regardless of | |
1164 | the value of @code{truncate-lines}. For information about side-by-side | |
1165 | windows, see @ref{Split Window}. See also @ref{Display,, Display, | |
1166 | elisp, The Emacs Lisp Reference Manual}. | |
1167 | ||
80174a97 KS |
1168 | @vindex overflow-newline-into-fringe |
1169 | If the variable @code{overflow-newline-into-fringe} is | |
54952612 RS |
1170 | non-@code{nil} on a graphical display, then Emacs does not continue or |
1171 | truncate a line which is exactly as wide as the window. Instead, the | |
1172 | newline overflows into the right fringe, and the cursor appears in the | |
1173 | fringe when positioned on that newline. | |
80174a97 | 1174 | |
9d3d42fb MB |
1175 | @node Temporary Face Changes |
1176 | @section Temporary Face Changes | |
1177 | ||
1178 | These are commands which temporarily change the default face used to | |
1179 | display text in a buffer. | |
1180 | ||
1181 | @cindex increase buffer face height | |
1182 | @findex increase-buffer-face-height | |
1183 | @cindex decrease buffer face height | |
1184 | @findex decrease-buffer-face-height | |
1185 | @findex text-scale-mode | |
1186 | To increase the size of the font used to display text in the current | |
1187 | buffer, type @kbd{C-=} or @kbd{C-+} | |
1188 | (@code{increase-buffer-face-height}). With a numeric prefix argument, | |
1189 | the size will be increased by that many steps (the default is 1 step); | |
1190 | each step scales the font height by the value of the variable | |
1191 | @code{text-scale-mode-step}. If repeated, this command has a | |
1192 | cumulative effect. As a special case, a prefix argument of 0 will | |
1193 | remove any scaling currently active. | |
1194 | ||
1195 | To decrease the size of the text, type @kbd{C--} | |
1196 | (@code{decrease-buffer-face-height}). The behavior is similar to that | |
1197 | of @code{increase-buffer-face-height}, but in reverse. | |
1198 | ||
1199 | These commands automatically enable or disable the | |
1200 | @code{text-scale-mode} minor-mode, depending on whether the current | |
1201 | font scaling is other than 1 or not. | |
1202 | ||
1203 | @cindex variable pitch mode | |
1204 | @findex variable-pitch-mode | |
1205 | To temporarily change the display face in the current buffer to a | |
1206 | variable-pitch (``proportional'') font, use the command @kbd{M-x | |
1207 | variable-pitch-mode} to enable or disable the Variable Pitch minor | |
1208 | mode. | |
1209 | ||
9d2908a6 RS |
1210 | @node Display Custom |
1211 | @section Customization of Display | |
80174a97 | 1212 | |
9d2908a6 RS |
1213 | This section describes variables (@pxref{Variables}) that you can |
1214 | change to customize how Emacs displays. Beginning users can skip | |
1215 | it. | |
1216 | @c the reason for that pxref is because an xref early in the | |
1217 | @c ``echo area'' section leads here. | |
62ea61af | 1218 | |
9d2908a6 RS |
1219 | @vindex inverse-video |
1220 | If the variable @code{inverse-video} is non-@code{nil}, Emacs attempts | |
1221 | to invert all the lines of the display from what they normally are. | |
62ea61af | 1222 | |
9d2908a6 RS |
1223 | @vindex visible-bell |
1224 | If the variable @code{visible-bell} is non-@code{nil}, Emacs attempts | |
1225 | to make the whole screen blink when it would normally make an audible bell | |
1226 | sound. This variable has no effect if your terminal does not have a way | |
1227 | to make the screen blink. | |
80174a97 | 1228 | |
9d2908a6 RS |
1229 | @vindex echo-keystrokes |
1230 | The variable @code{echo-keystrokes} controls the echoing of multi-character | |
1231 | keys; its value is the number of seconds of pause required to cause echoing | |
1232 | to start, or zero, meaning don't echo at all. The value takes effect when | |
1233 | there is someting to echo. @xref{Echo Area}. | |
80174a97 | 1234 | |
6bf7aab6 | 1235 | @vindex baud-rate |
54952612 RS |
1236 | The variable @anchor{baud-rate}@code{baud-rate} holds the output |
1237 | speed of the terminal, as far as Emacs knows. Setting this variable | |
1238 | does not change the speed of actual data transmission, but the value | |
1239 | is used for calculations. On text-only terminals, it affects padding, | |
1240 | and decisions about whether to scroll part of the screen or redraw it | |
1241 | instead. It also affects the behavior of incremental search. | |
1242 | ||
1243 | On graphical displays, @code{baud-rate} is only used to determine | |
1244 | how frequently to look for pending input during display updating. A | |
e598186c RS |
1245 | higher value of @code{baud-rate} means that check for pending input |
1246 | will be done less frequently. | |
6bf7aab6 | 1247 | |
62095f01 GM |
1248 | @cindex hourglass pointer display |
1249 | @vindex hourglass-delay | |
54952612 | 1250 | On graphical display, Emacs can optionally display the mouse pointer |
099bfef9 RS |
1251 | in a special shape to say that Emacs is busy. To turn this feature on |
1252 | or off, customize the group @code{cursor}. You can also control the | |
1253 | amount of time Emacs must remain busy before the busy indicator is | |
62095f01 | 1254 | displayed, by setting the variable @code{hourglass-delay}. |
099bfef9 | 1255 | |
9d2908a6 | 1256 | @vindex overline-margin |
3ae8f876 | 1257 | On graphical display, the variable @code{overline-margin} specifies the vertical position |
9d2908a6 RS |
1258 | of an overline above the text, including the height of the overline |
1259 | itself (1 pixel). The default value is 2 pixels. | |
1260 | ||
1261 | @vindex x-underline-at-descent-line | |
1262 | On graphical display, Emacs normally draws an underline at the | |
1263 | baseline level of the font. If @code{x-underline-at-descent-line} is | |
1264 | non-@code{nil}, Emacs draws the underline at the same height as the | |
1265 | font's descent line. | |
1266 | ||
a66b12be RS |
1267 | @findex tty-suppress-bold-inverse-default-colors |
1268 | On some text-only terminals, bold face and inverse video together | |
1269 | result in text that is hard to read. Call the function | |
1270 | @code{tty-suppress-bold-inverse-default-colors} with a non-@code{nil} | |
1271 | argument to suppress the effect of bold-face in this case. | |
1272 | ||
54952612 RS |
1273 | @vindex no-redraw-on-reenter |
1274 | On a text-only terminal, when you reenter Emacs after suspending, Emacs | |
1275 | normally clears the screen and redraws the entire display. On some | |
1276 | terminals with more than one page of memory, it is possible to arrange | |
1277 | the termcap entry so that the @samp{ti} and @samp{te} strings (output | |
1278 | to the terminal when Emacs is entered and exited, respectively) switch | |
1279 | between pages of memory so as to use one page for Emacs and another | |
43d67313 | 1280 | page for other output. On such terminals, you might want to set the variable |
54952612 RS |
1281 | @code{no-redraw-on-reenter} non-@code{nil}; this tells Emacs to |
1282 | assume, when resumed, that the screen page it is using still contains | |
1283 | what Emacs last wrote there. | |
1284 | ||
ab5796a9 MB |
1285 | @ignore |
1286 | arch-tag: 2219f910-2ff0-4521-b059-1bd231a536c4 | |
1287 | @end ignore |