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1 | @c This is part of the Emacs manual. |
2 | @c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997 Free Software Foundation, Inc. | |
3 | @c See file emacs.texi for copying conditions. | |
4 | @node Screen, User Input, Acknowledgments, Top | |
5 | @chapter The Organization of the Screen | |
6 | @cindex screen | |
7 | @cindex parts of the screen | |
8 | @c | |
9 | ||
10 | On a text-only terminal, the Emacs display occupies the whole screen. | |
11 | On the X Window System, Emacs creates its own X windows to use. We use | |
12 | the term @dfn{frame} to mean an entire text-only screen or an entire X | |
13 | window used by Emacs. Emacs uses both kinds of frames in the same way | |
14 | to display your editing. Emacs normally starts out with just one frame, | |
15 | but you can create additional frames if you wish. @xref{Frames}. | |
16 | ||
17 | When you start Emacs, the entire frame except for the first and last | |
18 | lines is devoted to the text you are editing. This area is called the | |
19 | @dfn{window}. The first line is a @dfn{menu bar}, and the last line is | |
20 | a special @dfn{echo area} or @dfn{minibuffer window} where prompts | |
21 | appear and where you can enter responses. See below for more | |
22 | information about these special lines. | |
23 | ||
24 | You can subdivide the large text window horizontally or vertically | |
25 | into multiple text windows, each of which can be used for a different | |
26 | file (@pxref{Windows}). In this manual, the word ``window'' always | |
27 | refers to the subdivisions of a frame within Emacs. | |
28 | ||
29 | The window that the cursor is in is the @dfn{selected window}, in | |
30 | which editing takes place. Most Emacs commands implicitly apply to the | |
31 | text in the selected window (though mouse commands generally operate on | |
32 | whatever window you click them in, whether selected or not). The other | |
33 | windows display text for reference only, unless/until you select them. | |
34 | If you use multiple frames under the X Window System, then giving the | |
35 | input focus to a particular frame selects a window in that frame. | |
36 | ||
37 | Each window's last line is a @dfn{mode line}, which describes what is | |
38 | going on in that window. It appears in inverse video, if the terminal | |
39 | supports that, and its contents begin with @w{@samp{--:-- @ *scratch*}} | |
40 | when Emacs starts. The mode line displays status information such as | |
41 | what buffer is being displayed above it in the window, what major and | |
42 | minor modes are in use, and whether the buffer contains unsaved changes. | |
43 | ||
44 | @menu | |
45 | * Point:: The place in the text where editing commands operate. | |
46 | * Echo Area:: Short messages appear at the bottom of the screen. | |
47 | * Mode Line:: Interpreting the mode line. | |
48 | * Menu Bar:: How to use the menu bar. | |
49 | @end menu | |
50 | ||
51 | @node Point | |
52 | @section Point | |
53 | @cindex point | |
54 | @cindex cursor | |
55 | ||
56 | Within Emacs, the terminal's cursor shows the location at which | |
57 | editing commands will take effect. This location is called @dfn{point}. | |
58 | Many Emacs commands move point through the text, so that you can edit at | |
59 | different places in it. You can also place point by clicking mouse | |
60 | button 1. | |
61 | ||
62 | While the cursor appears to point @emph{at} a character, you should | |
63 | think of point as @emph{between} two characters; it points @emph{before} | |
64 | the character that appears under the cursor. For example, if your text | |
65 | looks like @samp{frob} with the cursor over the @samp{b}, then point is | |
66 | between the @samp{o} and the @samp{b}. If you insert the character | |
67 | @samp{!} at that position, the result is @samp{fro!b}, with point | |
68 | between the @samp{!} and the @samp{b}. Thus, the cursor remains over | |
69 | the @samp{b}, as before. | |
70 | ||
71 | Sometimes people speak of ``the cursor'' when they mean ``point,'' or | |
72 | speak of commands that move point as ``cursor motion'' commands. | |
73 | ||
74 | Terminals have only one cursor, and when output is in progress it must | |
75 | appear where the typing is being done. This does not mean that point is | |
76 | moving. It is only that Emacs has no way to show you the location of point | |
77 | except when the terminal is idle. | |
78 | ||
79 | If you are editing several files in Emacs, each in its own buffer, | |
80 | each buffer has its own point location. A buffer that is not currently | |
81 | displayed remembers where point is in case you display it again later. | |
82 | ||
83 | When there are multiple windows in a frame, each window has its own | |
84 | point location. The cursor shows the location of point in the selected | |
85 | window. This also is how you can tell which window is selected. If the | |
86 | same buffer appears in more than one window, each window has its own | |
87 | position for point in that buffer. | |
88 | ||
89 | When there are multiple frames, each frame can display one cursor. | |
90 | The cursor in the selected frame is solid; the cursor in other frames is | |
91 | a hollow box, and appears in the window that would be selected if you | |
92 | give the input focus to that frame. | |
93 | ||
94 | The term `point' comes from the character @samp{.}, which was the | |
95 | command in TECO (the language in which the original Emacs was written) | |
96 | for accessing the value now called `point'. | |
97 | ||
98 | @node Echo Area | |
99 | @section The Echo Area | |
100 | @cindex echo area | |
101 | @c | |
102 | ||
103 | The line at the bottom of the frame (below the mode line) is the | |
104 | @dfn{echo area}. It is used to display small amounts of text for | |
105 | several purposes. | |
106 | ||
107 | @dfn{Echoing} means displaying the characters that you type. Outside | |
108 | Emacs, the operating system normally echoes all your input. Emacs | |
109 | handles echoing differently. | |
110 | ||
111 | Single-character commands do not echo in Emacs, and multi-character | |
112 | commands echo only if you pause while typing them. As soon as you pause | |
113 | for more than a second in the middle of a command, Emacs echoes all the | |
114 | characters of the command so far. This is to @dfn{prompt} you for the | |
115 | rest of the command. Once echoing has started, the rest of the command | |
116 | echoes immediately as you type it. This behavior is designed to give | |
117 | confident users fast response, while giving hesitant users maximum | |
118 | feedback. You can change this behavior by setting a variable | |
119 | (@pxref{Display Vars}). | |
120 | ||
121 | @cindex error message in the echo area | |
122 | If a command cannot be executed, it may print an @dfn{error message} in | |
123 | the echo area. Error messages are accompanied by a beep or by flashing the | |
124 | screen. Also, any input you have typed ahead is thrown away when an error | |
125 | happens. | |
126 | ||
127 | Some commands print informative messages in the echo area. These | |
128 | messages look much like error messages, but they are not announced with | |
129 | a beep and do not throw away input. Sometimes the message tells you | |
130 | what the command has done, when this is not obvious from looking at the | |
131 | text being edited. Sometimes the sole purpose of a command is to print | |
132 | a message giving you specific information---for example, @kbd{C-x =} | |
133 | prints a message describing the character position of point in the text | |
134 | and its current column in the window. Commands that take a long time | |
135 | often display messages ending in @samp{...} while they are working, and | |
136 | add @samp{done} at the end when they are finished. | |
137 | ||
138 | @cindex @samp{*Messages*} buffer | |
139 | @cindex saved echo area messages | |
140 | @cindex messages saved from echo area | |
141 | Echo-area informative messages are saved in an editor buffer named | |
142 | @samp{*Messages*}. (We have not explained buffers yet; see | |
143 | @ref{Buffers}, for more information about them.) If you miss a message | |
144 | that appears briefly on the screen, you can switch to the | |
145 | @samp{*Messages*} buffer to see it again. (Successive progress messages | |
146 | are often collapsed into one in that buffer.) | |
147 | ||
148 | @vindex message-log-max | |
149 | The size of @samp{*Messages*} is limited to a certain number of lines. | |
150 | The variable @code{message-log-max} specifies how many lines. Once the | |
151 | buffer has that many lines, each line added at the end deletes one line | |
152 | from the beginning. @xref{Variables}, for how to set variables such as | |
153 | @code{message-log-max}. | |
154 | ||
155 | The echo area is also used to display the @dfn{minibuffer}, a window that | |
156 | is used for reading arguments to commands, such as the name of a file to be | |
157 | edited. When the minibuffer is in use, the echo area begins with a prompt | |
158 | string that usually ends with a colon; also, the cursor appears in that line | |
159 | because it is the selected window. You can always get out of the | |
160 | minibuffer by typing @kbd{C-g}. @xref{Minibuffer}. | |
161 | ||
162 | @node Mode Line | |
163 | @section The Mode Line | |
164 | @cindex mode line | |
165 | @cindex top level | |
166 | @c | |
167 | ||
168 | Each text window's last line is a @dfn{mode line}, which describes what | |
169 | is going on in that window. When there is only one text window, the | |
170 | mode line appears right above the echo area; it is the next-to-last line | |
171 | on the frame. The mode line is in inverse video if the terminal | |
172 | supports that, and it starts and ends with dashes. | |
173 | ||
174 | Normally, the mode line looks like this: | |
175 | ||
176 | @example | |
177 | -@var{cs}:@var{ch} @var{buf} (@var{major} @var{minor})--@var{line}--@var{pos}------ | |
178 | @end example | |
179 | ||
180 | @noindent | |
181 | This gives information about the buffer being displayed in the window: the | |
182 | buffer's name, what major and minor modes are in use, whether the buffer's | |
183 | text has been changed, and how far down the buffer you are currently | |
184 | looking. | |
185 | ||
186 | @var{ch} contains two stars @samp{**} if the text in the buffer has | |
187 | been edited (the buffer is ``modified''), or @samp{--} if the buffer has | |
188 | not been edited. For a read-only buffer, it is @samp{%*} if the buffer | |
189 | is modified, and @samp{%%} otherwise. | |
190 | ||
191 | @var{buf} is the name of the window's @dfn{buffer}. In most cases | |
192 | this is the same as the name of a file you are editing. @xref{Buffers}. | |
193 | ||
194 | The buffer displayed in the selected window (the window that the | |
195 | cursor is in) is also Emacs's selected buffer, the one that editing | |
196 | takes place in. When we speak of what some command does to ``the | |
197 | buffer,'' we are talking about the currently selected buffer. | |
198 | ||
199 | @var{line} is @samp{L} followed by the current line number of point. | |
200 | This is present when Line Number mode is enabled (which it normally is). | |
201 | You can optionally display the current column number too, by turning on | |
202 | Column Number mode (which is not enabled by default because it is | |
203 | somewhat slower). @xref{Optional Mode Line}. | |
204 | ||
205 | @var{pos} tells you whether there is additional text above the top of | |
206 | the window, or below the bottom. If your buffer is small and it is all | |
207 | visible in the window, @var{pos} is @samp{All}. Otherwise, it is | |
208 | @samp{Top} if you are looking at the beginning of the buffer, @samp{Bot} | |
209 | if you are looking at the end of the buffer, or @samp{@var{nn}%}, where | |
210 | @var{nn} is the percentage of the buffer above the top of the | |
211 | window.@refill | |
212 | ||
213 | @var{major} is the name of the @dfn{major mode} in effect in the | |
214 | buffer. At any time, each buffer is in one and only one of the possible | |
215 | major modes. The major modes available include Fundamental mode (the | |
216 | least specialized), Text mode, Lisp mode, C mode, Texinfo mode, and many | |
217 | others. @xref{Major Modes}, for details of how the modes differ and how | |
218 | to select one.@refill | |
219 | ||
220 | Some major modes display additional information after the major mode | |
221 | name. For example, Rmail buffers display the current message number and | |
222 | the total number of messages. Compilation buffers and Shell buffers | |
223 | display the status of the subprocess. | |
224 | ||
225 | @var{minor} is a list of some of the @dfn{minor modes} that are turned | |
226 | on at the moment in the window's chosen buffer. For example, | |
227 | @samp{Fill} means that Auto Fill mode is on. @samp{Abbrev} means that | |
228 | Word Abbrev mode is on. @samp{Ovwrt} means that Overwrite mode is on. | |
229 | @xref{Minor Modes}, for more information. @samp{Narrow} means that the | |
230 | buffer being displayed has editing restricted to only a portion of its | |
231 | text. This is not really a minor mode, but is like one. | |
232 | @xref{Narrowing}. @samp{Def} means that a keyboard macro is being | |
233 | defined. @xref{Keyboard Macros}. | |
234 | ||
235 | In addition, if Emacs is currently inside a recursive editing level, | |
236 | square brackets (@samp{[@dots{}]}) appear around the parentheses that | |
237 | surround the modes. If Emacs is in one recursive editing level within | |
238 | another, double square brackets appear, and so on. Since recursive | |
239 | editing levels affect Emacs globally, not just one buffer, the square | |
240 | brackets appear in every window's mode line or not in any of them. | |
241 | @xref{Recursive Edit}.@refill | |
242 | ||
243 | Non-windowing terminals can only show a single Emacs frame at a time | |
244 | (@pxref{Frames}). On such terminals, the mode line displays the name of | |
245 | the selected frame, after @var{ch}. The initial frame's name is | |
246 | @samp{F1}. | |
247 | ||
248 | @var{cs} states the coding system used for the file you are editing. | |
249 | A dash indicates the default state of affairs: no code conversion, | |
250 | except for end-of-line translation if the file contents call for that. | |
251 | @samp{=} means no conversion whatsoever. Nontrivial code conversions | |
252 | are represented by various letters---for example, @samp{1} refers to ISO | |
253 | Latin-1. @xref{Coding Systems}, for more information. If you are using | |
254 | an input method, a string of the form @samp{@var{i}>} is added to the | |
255 | beginning of @var{cs}; @var{i} identifies the input method. (Some input | |
256 | methods show @samp{+} or @samp{@@} instead of @samp{>}.) @xref{Input | |
257 | Methods}. | |
258 | ||
259 | When you are using a character-only terminal (not a window system), | |
260 | @var{cs} uses three characters to describe, respectively, the coding | |
261 | system for keyboard input, the coding system for terminal output, and | |
262 | the coding system used for the file you are editing. | |
263 | ||
264 | When multibyte characters are not enabled, @var{cs} does not appear at | |
265 | all. @xref{Enabling Multibyte}. | |
266 | ||
267 | @cindex end-of-line conversion, mode-line indication | |
268 | The colon after @var{cs} can change to another string in certain | |
269 | circumstances. Emacs uses newline to separate lines in the buffer. | |
270 | Some files use different conventions for separating lines: either | |
271 | carriage-return linefeed (the MS-DOS convention) or just carriage-return | |
272 | (the Macintosh convention). If the buffer's file uses carriage-return | |
273 | linefeed, the colon changes to either a backslash (@samp{\}) or | |
274 | @samp{(DOS)}, depending on the operating system. If the file uses just | |
275 | carriage-return, the colon indicator changes to either a forward slash | |
276 | (@samp{/}) or @samp{(Mac)}. On some systems, Emacs displays | |
277 | @samp{(Unix)} instead of the colon even for files that use newline to | |
278 | separate lines. | |
279 | ||
280 | @vindex eol-mnemonic-unix | |
281 | @vindex eol-mnemonic-dos | |
282 | @vindex eol-mnemonic-mac | |
283 | @vindex eol-mnemonic-undecided | |
284 | You can customize the mode line display for each of the end-of-line | |
285 | formats by setting each of the variables @code{eol-mnemonic-unix}, | |
286 | @code{eol-mnemonic-dos}, @code{eol-mnemonic-mac}, and | |
287 | @code{eol-mnemonic-undecided} to any string you find appropriate. | |
288 | @xref{Variables}, for an explanation how to set variables. | |
289 | ||
290 | @xref{Optional Mode Line}, for features that add other handy | |
291 | information to the mode line, such as the current column number of | |
292 | point, the current time, and whether new mail for you has arrived. | |
293 | ||
294 | @node Menu Bar | |
295 | @section The Menu Bar | |
296 | @cindex menu bar | |
297 | ||
298 | Each Emacs frame normally has a @dfn{menu bar} at the top which you | |
299 | can use to perform certain common operations. There's no need to list | |
300 | them here, as you can more easily see for yourself. | |
301 | ||
302 | @kindex M-` | |
303 | @kindex F10 | |
304 | @findex tmm-menubar | |
305 | When you are using a window system, you can use the mouse to choose a | |
306 | command from the menu bar. An arrow pointing right, after the menu | |
307 | item, indicates that the item leads to a subsidiary menu; @samp{...} at | |
308 | the end means that the command will read arguments from the keyboard | |
309 | before it actually does anything. | |
310 | ||
311 | To view the full command name and documentation for a menu item, type | |
312 | @kbd{C-h k}, and then select the menu bar with the mouse in the usual | |
313 | way (@pxref{Key Help}). | |
314 | ||
315 | On text-only terminals with no mouse, you can use the menu bar by | |
316 | typing @kbd{M-`} or @key{F10} (these run the command | |
317 | @code{tmm-menubar}). This command enters a mode in which you can select | |
318 | a menu item from the keyboard. A provisional choice appears in the echo | |
319 | area. You can use the left and right arrow keys to move through the | |
320 | menu to different choices. When you have found the choice you want, | |
321 | type @key{RET} to select it. | |
322 | ||
323 | Each menu item also has an assigned letter or digit which designates | |
324 | that item; it is usually the initial of some word in the item's name. | |
325 | This letter or digit is separated from the item name by @samp{=>}. You | |
326 | can type the item's letter or digit to select the item. | |
327 | ||
328 | Some of the commands in the menu bar have ordinary key bindings as | |
329 | well; if so, the menu lists one equivalent key binding in parentheses | |
330 | after the item itself. |