2 @c This is part of the GNU Emacs Lisp Reference Manual.
3 @c Copyright (C) 1990-1995, 1998-1999, 2001-2014 Free Software
5 @c See the file elisp.texi for copying conditions.
10 A @dfn{frame} is a screen object that contains one or more Emacs
11 windows (@pxref{Windows}). It is the kind of object called a
12 ``window'' in the terminology of graphical environments; but we can't
13 call it a ``window'' here, because Emacs uses that word in a different
14 way. In Emacs Lisp, a @dfn{frame object} is a Lisp object that
15 represents a frame on the screen. @xref{Frame Type}.
17 A frame initially contains a single main window and/or a minibuffer
18 window; you can subdivide the main window vertically or horizontally
19 into smaller windows. @xref{Splitting Windows}.
22 A @dfn{terminal} is a display device capable of displaying one or
23 more Emacs frames. In Emacs Lisp, a @dfn{terminal object} is a Lisp
24 object that represents a terminal. @xref{Terminal Type}.
27 @cindex graphical terminal
28 @cindex graphical display
29 There are two classes of terminals: @dfn{text terminals} and
30 @dfn{graphical terminals}. Text terminals are non-graphics-capable
31 displays, including @command{xterm} and other terminal emulators. On
32 a text terminal, each Emacs frame occupies the terminal's entire
33 screen; although you can create additional frames and switch between
34 them, the terminal only shows one frame at a time. Graphical
35 terminals, on the other hand, are managed by graphical display systems
36 such as the X Window System, which allow Emacs to show multiple frames
37 simultaneously on the same display.
39 On GNU and Unix systems, you can create additional frames on any
40 available terminal, within a single Emacs session, regardless of
41 whether Emacs was started on a text or graphical terminal. Emacs can
42 display on both graphical and text terminals simultaneously. This
43 comes in handy, for instance, when you connect to the same session
44 from several remote locations. @xref{Multiple Terminals}.
47 This predicate returns a non-@code{nil} value if @var{object} is a
48 frame, and @code{nil} otherwise. For a frame, the value indicates which
49 kind of display the frame uses:
53 The frame is displayed on a text terminal.
55 The frame is displayed on an X graphical terminal.
57 The frame is displayed on a MS-Windows graphical terminal.
59 The frame is displayed on a GNUstep or Macintosh Cocoa graphical
62 The frame is displayed on an MS-DOS terminal.
66 @defun frame-terminal &optional frame
67 This function returns the terminal object that displays @var{frame}.
68 If @var{frame} is @code{nil} or unspecified, it defaults to the
72 @defun terminal-live-p object
73 This predicate returns a non-@code{nil} value if @var{object} is a
74 terminal that is live (i.e., not deleted), and @code{nil} otherwise.
75 For live terminals, the return value indicates what kind of frames are
76 displayed on that terminal; the list of possible values is the same as
77 for @code{framep} above.
81 * Creating Frames:: Creating additional frames.
82 * Multiple Terminals:: Displaying on several different devices.
83 * Frame Parameters:: Controlling frame size, position, font, etc.
84 * Terminal Parameters:: Parameters common for all frames on terminal.
85 * Frame Titles:: Automatic updating of frame titles.
86 * Deleting Frames:: Frames last until explicitly deleted.
87 * Finding All Frames:: How to examine all existing frames.
88 * Minibuffers and Frames:: How a frame finds the minibuffer to use.
89 * Input Focus:: Specifying the selected frame.
90 * Visibility of Frames:: Frames may be visible or invisible, or icons.
91 * Raising and Lowering:: Raising a frame makes it hide other windows;
92 lowering it makes the others hide it.
93 * Frame Configurations:: Saving the state of all frames.
94 * Mouse Tracking:: Getting events that say when the mouse moves.
95 * Mouse Position:: Asking where the mouse is, or moving it.
96 * Pop-Up Menus:: Displaying a menu for the user to select from.
97 * Dialog Boxes:: Displaying a box to ask yes or no.
98 * Pointer Shape:: Specifying the shape of the mouse pointer.
99 * Window System Selections:: Transferring text to and from other X clients.
100 * Drag and Drop:: Internals of Drag-and-Drop implementation.
101 * Color Names:: Getting the definitions of color names.
102 * Text Terminal Colors:: Defining colors for text terminals.
103 * Resources:: Getting resource values from the server.
104 * Display Feature Testing:: Determining the features of a terminal.
107 @node Creating Frames
108 @section Creating Frames
110 To create a new frame, call the function @code{make-frame}.
112 @deffn Command make-frame &optional alist
113 This function creates and returns a new frame, displaying the current
116 The @var{alist} argument is an alist that specifies frame parameters
117 for the new frame. @xref{Frame Parameters}. If you specify the
118 @code{terminal} parameter in @var{alist}, the new frame is created on
119 that terminal. Otherwise, if you specify the @code{window-system}
120 frame parameter in @var{alist}, that determines whether the frame
121 should be displayed on a text terminal or a graphical terminal.
122 @xref{Window Systems}. If neither is specified, the new frame is
123 created in the same terminal as the selected frame.
125 Any parameters not mentioned in @var{alist} default to the values in
126 the alist @code{default-frame-alist} (@pxref{Initial Parameters});
127 parameters not specified there default from the X resources or its
128 equivalent on your operating system (@pxref{X Resources,, X Resources,
129 emacs, The GNU Emacs Manual}). After the frame is created, Emacs
130 applies any parameters listed in @code{frame-inherited-parameters}
131 (see below) and not present in the argument, taking the values from
132 the frame that was selected when @code{make-frame} was called.
134 This function itself does not make the new frame the selected frame.
135 @xref{Input Focus}. The previously selected frame remains selected.
136 On graphical terminals, however, the windowing system may select the
137 new frame for its own reasons.
140 @defvar before-make-frame-hook
141 A normal hook run by @code{make-frame} before it creates the frame.
144 @defvar after-make-frame-functions
145 An abnormal hook run by @code{make-frame} after it creates the frame.
146 Each function in @code{after-make-frame-functions} receives one argument, the
150 @defvar frame-inherited-parameters
151 This variable specifies the list of frame parameters that a newly
152 created frame inherits from the currently selected frame. For each
153 parameter (a symbol) that is an element in the list and is not present
154 in the argument to @code{make-frame}, the function sets the value of
155 that parameter in the created frame to its value in the selected
159 @node Multiple Terminals
160 @section Multiple Terminals
161 @cindex multiple terminals
163 @cindex multiple X displays
164 @cindex displays, multiple
166 Emacs represents each terminal as a @dfn{terminal object} data type
167 (@pxref{Terminal Type}). On GNU and Unix systems, Emacs can use
168 multiple terminals simultaneously in each session. On other systems,
169 it can only use a single terminal. Each terminal object has the
170 following attributes:
174 The name of the device used by the terminal (e.g., @samp{:0.0} or
178 The terminal and keyboard coding systems used on the terminal.
179 @xref{Terminal I/O Encoding}.
182 The kind of display associated with the terminal. This is the symbol
183 returned by the function @code{terminal-live-p} (i.e., @code{x},
184 @code{t}, @code{w32}, @code{ns}, or @code{pc}). @xref{Frames}.
187 A list of terminal parameters. @xref{Terminal Parameters}.
190 There is no primitive for creating terminal objects. Emacs creates
191 them as needed, such as when you call @code{make-frame-on-display}
194 @defun terminal-name &optional terminal
195 This function returns the file name of the device used by
196 @var{terminal}. If @var{terminal} is omitted or @code{nil}, it
197 defaults to the selected frame's terminal. @var{terminal} can also be
198 a frame, meaning that frame's terminal.
202 This function returns a list of all live terminal objects.
205 @defun get-device-terminal device
206 This function returns a terminal whose device name is given by
207 @var{device}. If @var{device} is a string, it can be either the file
208 name of a terminal device, or the name of an X display of the form
209 @samp{@var{host}:@var{server}.@var{screen}}. If @var{device} is a
210 frame, this function returns that frame's terminal; @code{nil} means
211 the selected frame. Finally, if @var{device} is a terminal object
212 that represents a live terminal, that terminal is returned. The
213 function signals an error if its argument is none of the above.
216 @defun delete-terminal &optional terminal force
217 This function deletes all frames on @var{terminal} and frees the
218 resources used by it. It runs the abnormal hook
219 @code{delete-terminal-functions}, passing @var{terminal} as the
220 argument to each function.
222 If @var{terminal} is omitted or @code{nil}, it defaults to the
223 selected frame's terminal. @var{terminal} can also be a frame,
224 meaning that frame's terminal.
226 Normally, this function signals an error if you attempt to delete the
227 sole active terminal, but if @var{force} is non-@code{nil}, you are
228 allowed to do so. Emacs automatically calls this function when the
229 last frame on a terminal is deleted (@pxref{Deleting Frames}).
232 @defvar delete-terminal-functions
233 An abnormal hook run by @code{delete-terminal}. Each function
234 receives one argument, the @var{terminal} argument passed to
235 @code{delete-terminal}. Due to technical details, the functions may
236 be called either just before the terminal is deleted, or just
240 @cindex terminal-local variables
241 A few Lisp variables are @dfn{terminal-local}; that is, they have a
242 separate binding for each terminal. The binding in effect at any time
243 is the one for the terminal that the currently selected frame belongs
244 to. These variables include @code{default-minibuffer-frame},
245 @code{defining-kbd-macro}, @code{last-kbd-macro}, and
246 @code{system-key-alist}. They are always terminal-local, and can
247 never be buffer-local (@pxref{Buffer-Local Variables}).
249 On GNU and Unix systems, each X display is a separate graphical
250 terminal. When Emacs is started from within the X window system, it
251 uses the X display specified by the @env{DISPLAY} environment
252 variable, or by the @samp{--display} option (@pxref{Initial Options,,,
253 emacs, The GNU Emacs Manual}). Emacs can connect to other X displays
254 via the command @code{make-frame-on-display}. Each X display has its
255 own selected frame and its own minibuffer windows; however, only one
256 of those frames is ``@emph{the} selected frame'' at any given moment
257 (@pxref{Input Focus}). Emacs can even connect to other text
258 terminals, by interacting with the @command{emacsclient} program.
259 @xref{Emacs Server,,, emacs, The GNU Emacs Manual}.
261 A single X server can handle more than one display. Each X display
262 has a three-part name, @samp{@var{host}:@var{server}.@var{screen}}.
263 The first two parts, @var{host} and @var{server}, identify the X
264 server; the third part, @var{screen}, identifies a screen number on
265 that X server. When you use two or more screens belonging to one
266 server, Emacs knows by the similarity in their names that they share a
269 @deffn Command make-frame-on-display display &optional parameters
270 This function creates and returns a new frame on @var{display}, taking
271 the other frame parameters from the alist @var{parameters}.
272 @var{display} should be the name of an X display (a string).
274 Before creating the frame, this function ensures that Emacs is ``set
275 up'' to display graphics. For instance, if Emacs has not processed X
276 resources (e.g., if it was started on a text terminal), it does so at
277 this time. In all other respects, this function behaves like
278 @code{make-frame} (@pxref{Creating Frames}).
281 @defun x-display-list
282 This function returns a list that indicates which X displays Emacs has
283 a connection to. The elements of the list are strings, and each one
287 @defun x-open-connection display &optional xrm-string must-succeed
288 This function opens a connection to the X display @var{display},
289 without creating a frame on that display. Normally, Emacs Lisp
290 programs need not call this function, as @code{make-frame-on-display}
291 calls it automatically. The only reason for calling it is to check
292 whether communication can be established with a given X display.
294 The optional argument @var{xrm-string}, if not @code{nil}, is a string
295 of resource names and values, in the same format used in the
296 @file{.Xresources} file. @xref{X Resources,, X Resources, emacs, The
297 GNU Emacs Manual}. These values apply to all Emacs frames created on
298 this display, overriding the resource values recorded in the X server.
299 Here's an example of what this string might look like:
302 "*BorderWidth: 3\n*InternalBorder: 2\n"
305 If @var{must-succeed} is non-@code{nil}, failure to open the connection
306 terminates Emacs. Otherwise, it is an ordinary Lisp error.
309 @defun x-close-connection display
310 This function closes the connection to display @var{display}. Before
311 you can do this, you must first delete all the frames that were open
312 on that display (@pxref{Deleting Frames}).
315 @cindex multi-monitor
316 On some ``multi-monitor'' setups, a single X display outputs to more
317 than one physical monitor. @code{display-monitor-attributes-list} and
318 @code{frame-monitor-attributes} can be used to obtain information
319 about each physical monitor on multi-monitor setups.
321 @defun display-monitor-attributes-list &optional display
322 This function returns a list of physical monitor attributes on
323 @var{display}. Each element of the list is an association list,
324 representing the attributes of each physical monitor. The first
325 element corresponds to the primary monitor.
327 Attributes for a physical monitor are:
331 Position and size in pixels in the form of @samp{(X Y WIDTH HEIGHT)}
334 Position and size of the workarea in pixels in the form of @samp{(X Y
338 Width and height in millimeters in the form of @samp{(WIDTH HEIGHT)}
341 List of frames dominated by the physical monitor
344 Name of the physical monitor as a string
347 where X, Y, WIDTH, and HEIGHT are integers. @samp{name} is optional.
349 A frame is dominated by a physical monitor when either the
350 largest area of the frame resides in the monitor, or the monitor
351 is the closest to the frame if the frame does not intersect any
352 physical monitors. Every non-tip frame (including invisible one)
353 in a graphical display is dominated by exactly one physical
354 monitor at a time, though it can span multiple (or no) physical
357 @var{display} defaults to the selected frame's display.
360 @defun frame-monitor-attributes &optional frame
361 This function returns the attributes of the physical monitor
362 dominating @var{frame}, which defaults to the selected frame.
364 A frame is dominated by a physical monitor when either the
365 largest area of the frame resides in the monitor, or the monitor
366 is the closest to the frame if the frame does not intersect any
370 @node Frame Parameters
371 @section Frame Parameters
372 @cindex frame parameters
374 A frame has many parameters that control its appearance and behavior.
375 Just what parameters a frame has depends on what display mechanism it
378 Frame parameters exist mostly for the sake of graphical displays.
379 Most frame parameters have no effect when applied to a frame on a text
380 terminal; only the @code{height}, @code{width}, @code{name},
381 @code{title}, @code{menu-bar-lines}, @code{buffer-list} and
382 @code{buffer-predicate} parameters do something special. If the
383 terminal supports colors, the parameters @code{foreground-color},
384 @code{background-color}, @code{background-mode} and
385 @code{display-type} are also meaningful. If the terminal supports
386 frame transparency, the parameter @code{alpha} is also meaningful.
389 * Parameter Access:: How to change a frame's parameters.
390 * Initial Parameters:: Specifying frame parameters when you make a frame.
391 * Window Frame Parameters:: List of frame parameters for window systems.
392 * Size and Position:: Changing the size and position of a frame.
393 * Geometry:: Parsing geometry specifications.
396 @node Parameter Access
397 @subsection Access to Frame Parameters
399 These functions let you read and change the parameter values of a
402 @defun frame-parameter frame parameter
403 This function returns the value of the parameter @var{parameter} (a
404 symbol) of @var{frame}. If @var{frame} is @code{nil}, it returns the
405 selected frame's parameter. If @var{frame} has no setting for
406 @var{parameter}, this function returns @code{nil}.
409 @defun frame-parameters &optional frame
410 The function @code{frame-parameters} returns an alist listing all the
411 parameters of @var{frame} and their values. If @var{frame} is
412 @code{nil} or omitted, this returns the selected frame's parameters
415 @defun modify-frame-parameters frame alist
416 This function alters the parameters of frame @var{frame} based on the
417 elements of @var{alist}. Each element of @var{alist} has the form
418 @code{(@var{parm} . @var{value})}, where @var{parm} is a symbol naming a
419 parameter. If you don't mention a parameter in @var{alist}, its value
420 doesn't change. If @var{frame} is @code{nil}, it defaults to the selected
424 @defun set-frame-parameter frame parm value
425 This function sets the frame parameter @var{parm} to the specified
426 @var{value}. If @var{frame} is @code{nil}, it defaults to the
430 @defun modify-all-frames-parameters alist
431 This function alters the frame parameters of all existing frames
432 according to @var{alist}, then modifies @code{default-frame-alist}
433 (and, if necessary, @code{initial-frame-alist}) to apply the same
434 parameter values to frames that will be created henceforth.
437 @node Initial Parameters
438 @subsection Initial Frame Parameters
440 You can specify the parameters for the initial startup frame by
441 setting @code{initial-frame-alist} in your init file (@pxref{Init
444 @defopt initial-frame-alist
445 This variable's value is an alist of parameter values used when
446 creating the initial frame. You can set this variable to specify the
447 appearance of the initial frame without altering subsequent frames.
448 Each element has the form:
451 (@var{parameter} . @var{value})
454 Emacs creates the initial frame before it reads your init
455 file. After reading that file, Emacs checks @code{initial-frame-alist},
456 and applies the parameter settings in the altered value to the already
457 created initial frame.
459 If these settings affect the frame geometry and appearance, you'll see
460 the frame appear with the wrong ones and then change to the specified
461 ones. If that bothers you, you can specify the same geometry and
462 appearance with X resources; those do take effect before the frame is
463 created. @xref{X Resources,, X Resources, emacs, The GNU Emacs Manual}.
465 X resource settings typically apply to all frames. If you want to
466 specify some X resources solely for the sake of the initial frame, and
467 you don't want them to apply to subsequent frames, here's how to achieve
468 this. Specify parameters in @code{default-frame-alist} to override the
469 X resources for subsequent frames; then, to prevent these from affecting
470 the initial frame, specify the same parameters in
471 @code{initial-frame-alist} with values that match the X resources.
474 @cindex minibuffer-only frame
475 If these parameters include @code{(minibuffer . nil)}, that indicates
476 that the initial frame should have no minibuffer. In this case, Emacs
477 creates a separate @dfn{minibuffer-only frame} as well.
479 @defopt minibuffer-frame-alist
480 This variable's value is an alist of parameter values used when
481 creating an initial minibuffer-only frame (i.e., the minibuffer-only
482 frame that Emacs creates if @code{initial-frame-alist} specifies a
483 frame with no minibuffer).
486 @defopt default-frame-alist
487 This is an alist specifying default values of frame parameters for all
488 Emacs frames---the first frame, and subsequent frames. When using the X
489 Window System, you can get the same results by means of X resources
492 Setting this variable does not affect existing frames. Furthermore,
493 functions that display a buffer in a separate frame may override the
494 default parameters by supplying their own parameters.
497 If you invoke Emacs with command-line options that specify frame
498 appearance, those options take effect by adding elements to either
499 @code{initial-frame-alist} or @code{default-frame-alist}. Options
500 which affect just the initial frame, such as @samp{--geometry} and
501 @samp{--maximized}, add to @code{initial-frame-alist}; the others add
502 to @code{default-frame-alist}. @pxref{Emacs Invocation,, Command Line
503 Arguments for Emacs Invocation, emacs, The GNU Emacs Manual}.
505 @node Window Frame Parameters
506 @subsection Window Frame Parameters
507 @cindex frame parameters for windowed displays
509 Just what parameters a frame has depends on what display mechanism
510 it uses. This section describes the parameters that have special
511 meanings on some or all kinds of terminals. Of these, @code{name},
512 @code{title}, @code{height}, @code{width}, @code{buffer-list} and
513 @code{buffer-predicate} provide meaningful information in terminal
514 frames, and @code{tty-color-mode} is meaningful only for frames on
518 * Basic Parameters:: Parameters that are fundamental.
519 * Position Parameters:: The position of the frame on the screen.
520 * Size Parameters:: Frame's size.
521 * Layout Parameters:: Size of parts of the frame, and
522 enabling or disabling some parts.
523 * Buffer Parameters:: Which buffers have been or should be shown.
524 * Management Parameters:: Communicating with the window manager.
525 * Cursor Parameters:: Controlling the cursor appearance.
526 * Font and Color Parameters:: Fonts and colors for the frame text.
529 @node Basic Parameters
530 @subsubsection Basic Parameters
532 These frame parameters give the most basic information about the
533 frame. @code{title} and @code{name} are meaningful on all terminals.
536 @vindex display, a frame parameter
538 The display on which to open this frame. It should be a string of the
539 form @code{"@var{host}:@var{dpy}.@var{screen}"}, just like the
540 @env{DISPLAY} environment variable.
542 @vindex display-type, a frame parameter
544 This parameter describes the range of possible colors that can be used
545 in this frame. Its value is @code{color}, @code{grayscale} or
548 @vindex title, a frame parameter
550 If a frame has a non-@code{nil} title, it appears in the window
551 system's title bar at the top of the frame, and also in the mode line
552 of windows in that frame if @code{mode-line-frame-identification} uses
553 @samp{%F} (@pxref{%-Constructs}). This is normally the case when
554 Emacs is not using a window system, and can only display one frame at
555 a time. @xref{Frame Titles}.
557 @vindex name, a frame parameter
559 The name of the frame. The frame name serves as a default for the frame
560 title, if the @code{title} parameter is unspecified or @code{nil}. If
561 you don't specify a name, Emacs sets the frame name automatically
562 (@pxref{Frame Titles}).
564 If you specify the frame name explicitly when you create the frame, the
565 name is also used (instead of the name of the Emacs executable) when
566 looking up X resources for the frame.
569 If the frame name was specified explicitly when the frame was created,
570 this parameter will be that name. If the frame wasn't explicitly
571 named, this parameter will be @code{nil}.
574 @node Position Parameters
575 @subsubsection Position Parameters
576 @cindex window position on display
578 Position parameters' values are normally measured in pixels, but on
579 text terminals they count characters or lines instead.
582 @vindex left, a frame parameter
584 The position, in pixels, of the left (or right) edge of the frame with
585 respect to the left (or right) edge of the screen. The value may be:
589 A positive integer relates the left edge of the frame to the left edge
590 of the screen. A negative integer relates the right frame edge to the
593 @item @code{(+ @var{pos})}
594 This specifies the position of the left frame edge relative to the left
595 screen edge. The integer @var{pos} may be positive or negative; a
596 negative value specifies a position outside the screen.
598 @item @code{(- @var{pos})}
599 This specifies the position of the right frame edge relative to the right
600 screen edge. The integer @var{pos} may be positive or negative; a
601 negative value specifies a position outside the screen.
604 Some window managers ignore program-specified positions. If you want to
605 be sure the position you specify is not ignored, specify a
606 non-@code{nil} value for the @code{user-position} parameter as well.
608 @vindex top, a frame parameter
610 The screen position of the top (or bottom) edge, in pixels, with respect
611 to the top (or bottom) edge of the screen. It works just like
612 @code{left}, except vertically instead of horizontally.
614 @vindex icon-left, a frame parameter
616 The screen position of the left edge of the frame's icon, in pixels,
617 counting from the left edge of the screen. This takes effect when the
618 frame is iconified, if the window manager supports this feature. If
619 you specify a value for this parameter, then you must also specify a
620 value for @code{icon-top} and vice versa.
622 @vindex icon-top, a frame parameter
624 The screen position of the top edge of the frame's icon, in pixels,
625 counting from the top edge of the screen. This takes effect when the
626 frame is iconified, if the window manager supports this feature.
628 @vindex user-position, a frame parameter
630 When you create a frame and specify its screen position with the
631 @code{left} and @code{top} parameters, use this parameter to say whether
632 the specified position was user-specified (explicitly requested in some
633 way by a human user) or merely program-specified (chosen by a program).
634 A non-@code{nil} value says the position was user-specified.
636 @cindex window positions and window managers
637 Window managers generally heed user-specified positions, and some heed
638 program-specified positions too. But many ignore program-specified
639 positions, placing the window in a default fashion or letting the user
640 place it with the mouse. Some window managers, including @code{twm},
641 let the user specify whether to obey program-specified positions or
644 When you call @code{make-frame}, you should specify a non-@code{nil}
645 value for this parameter if the values of the @code{left} and @code{top}
646 parameters represent the user's stated preference; otherwise, use
650 @node Size Parameters
651 @subsubsection Size Parameters
652 @cindex window size on display
654 Frame parameters specify frame sizes in character units. On
655 graphical displays, the @code{default} face determines the actual
656 pixel sizes of these character units (@pxref{Face Attributes}).
659 @vindex height, a frame parameter
661 The height of the frame contents, in characters. (To get the height in
662 pixels, call @code{frame-pixel-height}; see @ref{Size and Position}.)
664 @vindex width, a frame parameter
666 The width of the frame contents, in characters. (To get the width in
667 pixels, call @code{frame-pixel-width}; see @ref{Size and Position}.)
669 @vindex user-size, a frame parameter
671 This does for the size parameters @code{height} and @code{width} what
672 the @code{user-position} parameter (@pxref{Position Parameters,
673 user-position}) does for the position parameters @code{top} and
676 @cindex full-screen frames
677 @vindex fullscreen, a frame parameter
679 Specify that width, height or both shall be maximized. The value
680 @code{fullwidth} specifies that width shall be as wide as possible.
681 The value @code{fullheight} specifies that height shall be as tall as
682 possible. The value @code{fullboth} specifies that both the width and
683 the height shall be set to the size of the screen. The value
684 @code{maximized} specifies that the frame shall be maximized. The
685 difference between @code{maximized} and @code{fullboth} is that the
686 former can still be resized by dragging window manager decorations
687 with the mouse, while the latter really covers the whole screen and
688 does not allow resizing by mouse dragging.
691 @node Layout Parameters
692 @subsubsection Layout Parameters
693 @cindex layout parameters of frames
694 @cindex frame layout parameters
696 These frame parameters enable or disable various parts of the
697 frame, or control their sizes.
700 @vindex border-width, a frame parameter
702 The width in pixels of the frame's border.
704 @vindex internal-border-width, a frame parameter
705 @item internal-border-width
706 The distance in pixels between text (or fringe) and the frame's border.
708 @vindex vertical-scroll-bars, a frame parameter
709 @item vertical-scroll-bars
710 Whether the frame has scroll bars for vertical scrolling, and which side
711 of the frame they should be on. The possible values are @code{left},
712 @code{right}, and @code{nil} for no scroll bars.
715 @vindex horizontal-scroll-bars, a frame parameter
716 @item horizontal-scroll-bars
717 Whether the frame has scroll bars for horizontal scrolling
718 (non-@code{nil} means yes). Horizontal scroll bars are not currently
722 @vindex scroll-bar-width, a frame parameter
723 @item scroll-bar-width
724 The width of vertical scroll bars, in pixels, or @code{nil} meaning to
725 use the default width.
727 @vindex left-fringe, a frame parameter
728 @vindex right-fringe, a frame parameter
731 The default width of the left and right fringes of windows in this
732 frame (@pxref{Fringes}). If either of these is zero, that effectively
733 removes the corresponding fringe.
735 When you use @code{frame-parameter} to query the value of either of
736 these two frame parameters, the return value is always an integer.
737 When using @code{set-frame-parameter}, passing a @code{nil} value
738 imposes an actual default value of 8 pixels.
740 The combined fringe widths must add up to an integral number of
741 columns, so the actual default fringe widths for the frame, as
742 reported by @code{frame-parameter}, may be larger than what you
743 specify. Any extra width is distributed evenly between the left and
744 right fringe. However, you can force one fringe or the other to a
745 precise width by specifying that width as a negative integer. If both
746 widths are negative, only the left fringe gets the specified width.
748 @vindex menu-bar-lines frame parameter
750 The number of lines to allocate at the top of the frame for a menu
751 bar. The default is 1 if Menu Bar mode is enabled, and 0 otherwise.
752 @xref{Menu Bars,,,emacs, The GNU Emacs Manual}.
754 @vindex tool-bar-lines frame parameter
756 The number of lines to use for the tool bar. The default is 1 if Tool
757 Bar mode is enabled, and 0 otherwise. @xref{Tool Bars,,,emacs, The
760 @vindex tool-bar-position frame parameter
761 @item tool-bar-position
762 The position of the tool bar. Currently only for the GTK tool bar.
763 Value can be one of @code{top}, @code{bottom} @code{left}, @code{right}.
764 The default is @code{top}.
766 @vindex line-spacing, a frame parameter
768 Additional space to leave below each text line, in pixels (a positive
769 integer). @xref{Line Height}, for more information.
772 @node Buffer Parameters
773 @subsubsection Buffer Parameters
775 These frame parameters, meaningful on all kinds of terminals, deal
776 with which buffers have been, or should, be displayed in the frame.
779 @vindex minibuffer, a frame parameter
781 Whether this frame has its own minibuffer. The value @code{t} means
782 yes, @code{nil} means no, @code{only} means this frame is just a
783 minibuffer. If the value is a minibuffer window (in some other
784 frame), the frame uses that minibuffer.
786 This frame parameter takes effect when the frame is created, and can
787 not be changed afterwards.
789 @vindex buffer-predicate, a frame parameter
790 @item buffer-predicate
791 The buffer-predicate function for this frame. The function
792 @code{other-buffer} uses this predicate (from the selected frame) to
793 decide which buffers it should consider, if the predicate is not
794 @code{nil}. It calls the predicate with one argument, a buffer, once for
795 each buffer; if the predicate returns a non-@code{nil} value, it
796 considers that buffer.
798 @vindex buffer-list, a frame parameter
800 A list of buffers that have been selected in this frame, ordered
801 most-recently-selected first.
803 @vindex unsplittable, a frame parameter
805 If non-@code{nil}, this frame's window is never split automatically.
808 @node Management Parameters
809 @subsubsection Window Management Parameters
810 @cindex window manager interaction, and frame parameters
812 The following frame parameters control various aspects of the
813 frame's interaction with the window manager. They have no effect on
817 @vindex visibility, a frame parameter
819 The state of visibility of the frame. There are three possibilities:
820 @code{nil} for invisible, @code{t} for visible, and @code{icon} for
821 iconified. @xref{Visibility of Frames}.
823 @vindex auto-raise, a frame parameter
825 If non-@code{nil}, Emacs automatically raises the frame when it is
826 selected. Some window managers do not allow this.
828 @vindex auto-lower, a frame parameter
830 If non-@code{nil}, Emacs automatically lowers the frame when it is
831 deselected. Some window managers do not allow this.
833 @vindex icon-type, a frame parameter
835 The type of icon to use for this frame. If the value is a string,
836 that specifies a file containing a bitmap to use; @code{nil} specifies
837 no icon (in which case the window manager decides what to show); any
838 other non-@code{nil} value specifies the default Emacs icon.
840 @vindex icon-name, a frame parameter
842 The name to use in the icon for this frame, when and if the icon
843 appears. If this is @code{nil}, the frame's title is used.
845 @vindex window-id, a frame parameter
847 The ID number which the graphical display uses for this frame. Emacs
848 assigns this parameter when the frame is created; changing the
849 parameter has no effect on the actual ID number.
851 @vindex outer-window-id, a frame parameter
852 @item outer-window-id
853 The ID number of the outermost window-system window in which the frame
854 exists. As with @code{window-id}, changing this parameter has no
857 @vindex wait-for-wm, a frame parameter
859 If non-@code{nil}, tell Xt to wait for the window manager to confirm
860 geometry changes. Some window managers, including versions of Fvwm2
861 and KDE, fail to confirm, so Xt hangs. Set this to @code{nil} to
862 prevent hanging with those window managers.
864 @vindex sticky, a frame parameter
866 If non-@code{nil}, the frame is visible on all virtual desktops on systems
867 with virtual desktops.
870 @vindex parent-id, a frame parameter
872 @c ??? Not yet working.
873 The X window number of the window that should be the parent of this one.
874 Specifying this lets you create an Emacs window inside some other
875 application's window. (It is not certain this will be implemented; try
876 it and see if it works.)
880 @node Cursor Parameters
881 @subsubsection Cursor Parameters
882 @cindex cursor, and frame parameters
884 This frame parameter controls the way the cursor looks.
887 @vindex cursor-type, a frame parameter
889 How to display the cursor. Legitimate values are:
893 Display a filled box. (This is the default.)
895 Display a hollow box.
897 Don't display a cursor.
899 Display a vertical bar between characters.
900 @item (bar . @var{width})
901 Display a vertical bar @var{width} pixels wide between characters.
903 Display a horizontal bar.
904 @item (hbar . @var{height})
905 Display a horizontal bar @var{height} pixels high.
910 The @code{cursor-type} frame parameter may be overridden by the
911 variables @code{cursor-type} and
912 @code{cursor-in-non-selected-windows}:
915 This buffer-local variable controls how the cursor looks in a selected
916 window showing the buffer. If its value is @code{t}, that means to
917 use the cursor specified by the @code{cursor-type} frame parameter.
918 Otherwise, the value should be one of the cursor types listed above,
919 and it overrides the @code{cursor-type} frame parameter.
922 @defopt cursor-in-non-selected-windows
923 This buffer-local variable controls how the cursor looks in a window
924 that is not selected. It supports the same values as the
925 @code{cursor-type} frame parameter; also, @code{nil} means don't
926 display a cursor in nonselected windows, and @code{t} (the default)
927 means use a standard modification of the usual cursor type (solid box
928 becomes hollow box, and bar becomes a narrower bar).
931 @defopt blink-cursor-alist
932 This variable specifies how to blink the cursor. Each element has the
933 form @code{(@var{on-state} . @var{off-state})}. Whenever the cursor
934 type equals @var{on-state} (comparing using @code{equal}), the
935 corresponding @var{off-state} specifies what the cursor looks like
936 when it blinks ``off''. Both @var{on-state} and @var{off-state}
937 should be suitable values for the @code{cursor-type} frame parameter.
939 There are various defaults for how to blink each type of cursor, if
940 the type is not mentioned as an @var{on-state} here. Changes in this
941 variable do not take effect immediately, only when you specify the
942 @code{cursor-type} frame parameter.
945 @node Font and Color Parameters
946 @subsubsection Font and Color Parameters
947 @cindex font and color, frame parameters
949 These frame parameters control the use of fonts and colors.
952 @vindex font-backend, a frame parameter
954 A list of symbols, specifying the @dfn{font backends} to use for
955 drawing fonts in the frame, in order of priority. On X, there are
956 currently two available font backends: @code{x} (the X core font
957 driver) and @code{xft} (the Xft font driver). On Windows, there are
958 currently two available font backends: @code{gdi} and
959 @code{uniscribe} (@pxref{Windows Fonts,,, emacs, The GNU Emacs
960 Manual}). On other systems, there is only one available font backend,
961 so it does not make sense to modify this frame parameter.
963 @vindex background-mode, a frame parameter
964 @item background-mode
965 This parameter is either @code{dark} or @code{light}, according
966 to whether the background color is a light one or a dark one.
968 @vindex tty-color-mode, a frame parameter
970 @cindex standard colors for character terminals
971 This parameter overrides the terminal's color support as given by the
972 system's terminal capabilities database in that this parameter's value
973 specifies the color mode to use on a text terminal. The value can be
974 either a symbol or a number. A number specifies the number of colors
975 to use (and, indirectly, what commands to issue to produce each
976 color). For example, @code{(tty-color-mode . 8)} specifies use of the
977 ANSI escape sequences for 8 standard text colors. A value of -1 turns
980 If the parameter's value is a symbol, it specifies a number through
981 the value of @code{tty-color-mode-alist}, and the associated number is
984 @vindex screen-gamma, a frame parameter
986 @cindex gamma correction
987 If this is a number, Emacs performs ``gamma correction'' which adjusts
988 the brightness of all colors. The value should be the screen gamma of
989 your display, a floating point number.
991 Usual PC monitors have a screen gamma of 2.2, so color values in
992 Emacs, and in X windows generally, are calibrated to display properly
993 on a monitor with that gamma value. If you specify 2.2 for
994 @code{screen-gamma}, that means no correction is needed. Other values
995 request correction, designed to make the corrected colors appear on
996 your screen the way they would have appeared without correction on an
997 ordinary monitor with a gamma value of 2.2.
999 If your monitor displays colors too light, you should specify a
1000 @code{screen-gamma} value smaller than 2.2. This requests correction
1001 that makes colors darker. A screen gamma value of 1.5 may give good
1002 results for LCD color displays.
1004 @vindex alpha, a frame parameter
1006 @cindex opacity, frame
1007 @cindex transparency, frame
1008 @vindex frame-alpha-lower-limit
1009 This parameter specifies the opacity of the frame, on graphical
1010 displays that support variable opacity. It should be an integer
1011 between 0 and 100, where 0 means completely transparent and 100 means
1012 completely opaque. It can also have a @code{nil} value, which tells
1013 Emacs not to set the frame opacity (leaving it to the window manager).
1015 To prevent the frame from disappearing completely from view, the
1016 variable @code{frame-alpha-lower-limit} defines a lower opacity limit.
1017 If the value of the frame parameter is less than the value of this
1018 variable, Emacs uses the latter. By default,
1019 @code{frame-alpha-lower-limit} is 20.
1021 The @code{alpha} frame parameter can also be a cons cell
1022 @code{(@samp{active} . @samp{inactive})}, where @samp{active} is the
1023 opacity of the frame when it is selected, and @samp{inactive} is the
1024 opacity when it is not selected.
1027 The following frame parameters are semi-obsolete in that they are
1028 automatically equivalent to particular face attributes of particular
1029 faces (@pxref{Standard Faces,,, emacs, The Emacs Manual}):
1032 @vindex font, a frame parameter
1034 The name of the font for displaying text in the frame. This is a
1035 string, either a valid font name for your system or the name of an Emacs
1036 fontset (@pxref{Fontsets}). It is equivalent to the @code{font}
1037 attribute of the @code{default} face.
1039 @vindex foreground-color, a frame parameter
1040 @item foreground-color
1041 The color to use for the image of a character. It is equivalent to
1042 the @code{:foreground} attribute of the @code{default} face.
1044 @vindex background-color, a frame parameter
1045 @item background-color
1046 The color to use for the background of characters. It is equivalent to
1047 the @code{:background} attribute of the @code{default} face.
1049 @vindex mouse-color, a frame parameter
1051 The color for the mouse pointer. It is equivalent to the @code{:background}
1052 attribute of the @code{mouse} face.
1054 @vindex cursor-color, a frame parameter
1056 The color for the cursor that shows point. It is equivalent to the
1057 @code{:background} attribute of the @code{cursor} face.
1059 @vindex border-color, a frame parameter
1061 The color for the border of the frame. It is equivalent to the
1062 @code{:background} attribute of the @code{border} face.
1064 @vindex scroll-bar-foreground, a frame parameter
1065 @item scroll-bar-foreground
1066 If non-@code{nil}, the color for the foreground of scroll bars. It is
1067 equivalent to the @code{:foreground} attribute of the
1068 @code{scroll-bar} face.
1070 @vindex scroll-bar-background, a frame parameter
1071 @item scroll-bar-background
1072 If non-@code{nil}, the color for the background of scroll bars. It is
1073 equivalent to the @code{:background} attribute of the
1074 @code{scroll-bar} face.
1077 @node Size and Position
1078 @subsection Frame Size And Position
1079 @cindex size of frame
1082 @cindex resize frame
1084 You can read or change the size and position of a frame using the
1085 frame parameters @code{left}, @code{top}, @code{height}, and
1086 @code{width}. Whatever geometry parameters you don't specify are chosen
1087 by the window manager in its usual fashion.
1089 Here are some special features for working with sizes and positions.
1090 (For the precise meaning of ``selected frame'' used by these functions,
1091 see @ref{Input Focus}.)
1093 @defun set-frame-position frame left top
1094 This function sets the position of the top left corner of @var{frame} to
1095 @var{left} and @var{top}. These arguments are measured in pixels, and
1096 normally count from the top left corner of the screen.
1098 Negative parameter values position the bottom edge of the window up from
1099 the bottom edge of the screen, or the right window edge to the left of
1100 the right edge of the screen. It would probably be better if the values
1101 were always counted from the left and top, so that negative arguments
1102 would position the frame partly off the top or left edge of the screen,
1103 but it seems inadvisable to change that now.
1106 @defun frame-height &optional frame
1107 @defunx frame-width &optional frame
1108 These functions return the height and width of @var{frame}, measured in
1109 lines and columns. If you don't supply @var{frame}, they use the
1113 @defun frame-pixel-height &optional frame
1114 @defunx frame-pixel-width &optional frame
1115 These functions return the height and width of the main display area
1116 of @var{frame}, measured in pixels. If you don't supply @var{frame},
1117 they use the selected frame. For a text terminal, the results are in
1118 characters rather than pixels.
1120 These values include the internal borders, and windows' scroll bars
1121 and fringes (which belong to individual windows, not to the frame
1122 itself). The exact value of the heights depends on the window-system
1123 and toolkit in use. With GTK+, the height does not include any tool
1124 bar or menu bar. With the Motif or Lucid toolkits, it includes the
1125 tool bar but not the menu bar. In a graphical version with no
1126 toolkit, it includes both the tool bar and menu bar. For a text
1127 terminal, the result includes the menu bar.
1130 @defun frame-char-height &optional frame
1131 @defunx frame-char-width &optional frame
1132 These functions return the height and width of a character in
1133 @var{frame}, measured in pixels. The values depend on the choice of
1134 font. If you don't supply @var{frame}, these functions use the selected
1138 @defun set-frame-size frame cols rows
1139 This function sets the size of @var{frame}, measured in characters;
1140 @var{cols} and @var{rows} specify the new width and height.
1142 To set the size based on values measured in pixels, use
1143 @code{frame-char-height} and @code{frame-char-width} to convert
1144 them to units of characters.
1147 @defun set-frame-height frame lines &optional pretend
1148 This function resizes @var{frame} to a height of @var{lines} lines. The
1149 sizes of existing windows in @var{frame} are altered proportionally to
1152 If @var{pretend} is non-@code{nil}, then Emacs displays @var{lines}
1153 lines of output in @var{frame}, but does not change its value for the
1154 actual height of the frame. This is only useful on text terminals.
1155 Using a smaller height than the terminal actually implements may be
1156 useful to reproduce behavior observed on a smaller screen, or if the
1157 terminal malfunctions when using its whole screen. Setting the frame
1158 height ``for real'' does not always work, because knowing the correct
1159 actual size may be necessary for correct cursor positioning on
1163 @defun set-frame-width frame width &optional pretend
1164 This function sets the width of @var{frame}, measured in characters.
1165 The argument @var{pretend} has the same meaning as in
1166 @code{set-frame-height}.
1169 @c FIXME? Belongs more in Emacs manual than here?
1170 @c But, e.g., fit-window-to-buffer is in this manual.
1171 @deffn Command fit-frame-to-buffer &optional frame max-height min-height
1172 This command adjusts the height of @var{frame} (the default is the
1173 selected frame) to fit its contents. The optional arguments
1174 @var{max-height} and @var{min-height} specify the maximum and minimum
1175 new frame heights, respectively.
1177 @vindex fit-frame-to-buffer-bottom-margin
1178 The default minimum height corresponds to @code{window-min-height}.
1179 The default maximum height is the screen height below the current top
1180 position of the frame, minus any margin specified by the option
1181 @code{fit-frame-to-buffer-bottom-margin}.
1185 @subsection Geometry
1187 Here's how to examine the data in an X-style window geometry
1190 @defun x-parse-geometry geom
1191 @cindex geometry specification
1192 The function @code{x-parse-geometry} converts a standard X window
1193 geometry string to an alist that you can use as part of the argument to
1196 The alist describes which parameters were specified in @var{geom}, and
1197 gives the values specified for them. Each element looks like
1198 @code{(@var{parameter} . @var{value})}. The possible @var{parameter}
1199 values are @code{left}, @code{top}, @code{width}, and @code{height}.
1201 For the size parameters, the value must be an integer. The position
1202 parameter names @code{left} and @code{top} are not totally accurate,
1203 because some values indicate the position of the right or bottom edges
1204 instead. The @var{value} possibilities for the position parameters are:
1205 an integer, a list @code{(+ @var{pos})}, or a list @code{(- @var{pos})};
1206 as previously described (@pxref{Position Parameters}).
1211 (x-parse-geometry "35x70+0-0")
1212 @result{} ((height . 70) (width . 35)
1213 (top - 0) (left . 0))
1217 @node Terminal Parameters
1218 @section Terminal Parameters
1219 @cindex terminal parameters
1221 Each terminal has a list of associated parameters. These
1222 @dfn{terminal parameters} are mostly a convenient way of storage for
1223 terminal-local variables, but some terminal parameters have a special
1226 This section describes functions to read and change the parameter values
1227 of a terminal. They all accept as their argument either a terminal or
1228 a frame; the latter means use that frame's terminal. An argument of
1229 @code{nil} means the selected frame's terminal.
1231 @defun terminal-parameters &optional terminal
1232 This function returns an alist listing all the parameters of
1233 @var{terminal} and their values.
1236 @defun terminal-parameter terminal parameter
1237 This function returns the value of the parameter @var{parameter} (a
1238 symbol) of @var{terminal}. If @var{terminal} has no setting for
1239 @var{parameter}, this function returns @code{nil}.
1242 @defun set-terminal-parameter terminal parameter value
1243 This function sets the parameter @var{parm} of @var{terminal} to the
1244 specified @var{value}, and returns the previous value of that
1248 Here's a list of a few terminal parameters that have a special
1252 @item background-mode
1253 The classification of the terminal's background color, either
1254 @code{light} or @code{dark}.
1255 @item normal-erase-is-backspace
1256 Value is either 1 or 0, depending on whether
1257 @code{normal-erase-is-backspace-mode} is turned on or off on this
1258 terminal. @xref{DEL Does Not Delete,,, emacs, The Emacs Manual}.
1259 @item terminal-initted
1260 After the terminal is initialized, this is set to the
1261 terminal-specific initialization function.
1265 @section Frame Titles
1268 Every frame has a @code{name} parameter; this serves as the default
1269 for the frame title which window systems typically display at the top of
1270 the frame. You can specify a name explicitly by setting the @code{name}
1273 Normally you don't specify the name explicitly, and Emacs computes the
1274 frame name automatically based on a template stored in the variable
1275 @code{frame-title-format}. Emacs recomputes the name each time the
1276 frame is redisplayed.
1278 @defvar frame-title-format
1279 This variable specifies how to compute a name for a frame when you have
1280 not explicitly specified one. The variable's value is actually a mode
1281 line construct, just like @code{mode-line-format}, except that the
1282 @samp{%c} and @samp{%l} constructs are ignored. @xref{Mode Line
1286 @defvar icon-title-format
1287 This variable specifies how to compute the name for an iconified frame,
1288 when you have not explicitly specified the frame title. This title
1289 appears in the icon itself.
1292 @defvar multiple-frames
1293 This variable is set automatically by Emacs. Its value is @code{t} when
1294 there are two or more frames (not counting minibuffer-only frames or
1295 invisible frames). The default value of @code{frame-title-format} uses
1296 @code{multiple-frames} so as to put the buffer name in the frame title
1297 only when there is more than one frame.
1299 The value of this variable is not guaranteed to be accurate except
1300 while processing @code{frame-title-format} or
1301 @code{icon-title-format}.
1304 @node Deleting Frames
1305 @section Deleting Frames
1306 @cindex deleting frames
1308 A @dfn{live frame} is one that has not been deleted. When a frame
1309 is deleted, it is removed from its terminal display, although it may
1310 continue to exist as a Lisp object until there are no more references
1313 @deffn Command delete-frame &optional frame force
1314 @vindex delete-frame-functions
1315 This function deletes the frame @var{frame}. Unless @var{frame} is a
1316 tooltip, it first runs the hook @code{delete-frame-functions} (each
1317 function gets one argument, @var{frame}). By default, @var{frame} is
1320 A frame cannot be deleted if its minibuffer is used by other frames.
1321 Normally, you cannot delete a frame if all other frames are invisible,
1322 but if @var{force} is non-@code{nil}, then you are allowed to do so.
1325 @defun frame-live-p frame
1326 The function @code{frame-live-p} returns non-@code{nil} if the frame
1327 @var{frame} has not been deleted. The possible non-@code{nil} return
1328 values are like those of @code{framep}. @xref{Frames}.
1331 Some window managers provide a command to delete a window. These work
1332 by sending a special message to the program that operates the window.
1333 When Emacs gets one of these commands, it generates a
1334 @code{delete-frame} event, whose normal definition is a command that
1335 calls the function @code{delete-frame}. @xref{Misc Events}.
1337 @node Finding All Frames
1338 @section Finding All Frames
1339 @cindex frames, scanning all
1342 This function returns a list of all the live frames, i.e., those that
1343 have not been deleted. It is analogous to @code{buffer-list} for
1344 buffers, and includes frames on all terminals. The list that you get
1345 is newly created, so modifying the list doesn't have any effect on the
1349 @defun visible-frame-list
1350 This function returns a list of just the currently visible frames.
1351 @xref{Visibility of Frames}. Frames on text terminals always count as
1352 ``visible'', even though only the selected one is actually displayed.
1355 @defun next-frame &optional frame minibuf
1356 This function lets you cycle conveniently through all the frames on
1357 the current display from an arbitrary starting point. It returns the
1358 ``next'' frame after @var{frame} in the cycle. If @var{frame} is
1359 omitted or @code{nil}, it defaults to the selected frame (@pxref{Input
1362 The second argument, @var{minibuf}, says which frames to consider:
1366 Exclude minibuffer-only frames.
1367 @item @code{visible}
1368 Consider all visible frames.
1370 Consider all visible or iconified frames.
1372 Consider only the frames using that particular window as their
1375 Consider all frames.
1379 @defun previous-frame &optional frame minibuf
1380 Like @code{next-frame}, but cycles through all frames in the opposite
1384 See also @code{next-window} and @code{previous-window}, in @ref{Cyclic
1387 @node Minibuffers and Frames
1388 @section Minibuffers and Frames
1390 Normally, each frame has its own minibuffer window at the bottom, which
1391 is used whenever that frame is selected. If the frame has a minibuffer,
1392 you can get it with @code{minibuffer-window} (@pxref{Definition of
1393 minibuffer-window}).
1395 However, you can also create a frame with no minibuffer. Such a frame
1396 must use the minibuffer window of some other frame. When you create the
1397 frame, you can explicitly specify the minibuffer window to use (in some
1398 other frame). If you don't, then the minibuffer is found in the frame
1399 which is the value of the variable @code{default-minibuffer-frame}. Its
1400 value should be a frame that does have a minibuffer.
1402 If you use a minibuffer-only frame, you might want that frame to raise
1403 when you enter the minibuffer. If so, set the variable
1404 @code{minibuffer-auto-raise} to @code{t}. @xref{Raising and Lowering}.
1406 @defvar default-minibuffer-frame
1407 This variable specifies the frame to use for the minibuffer window, by
1408 default. It does not affect existing frames. It is always local to
1409 the current terminal and cannot be buffer-local. @xref{Multiple
1414 @section Input Focus
1416 @c @cindex selected frame Duplicates selected-frame, same for selected-window.
1418 At any time, one frame in Emacs is the @dfn{selected frame}. The selected
1419 window always resides on the selected frame.
1421 When Emacs displays its frames on several terminals (@pxref{Multiple
1422 Terminals}), each terminal has its own selected frame. But only one
1423 of these is ``@emph{the} selected frame'': it's the frame that belongs
1424 to the terminal from which the most recent input came. That is, when
1425 Emacs runs a command that came from a certain terminal, the selected
1426 frame is the one of that terminal. Since Emacs runs only a single
1427 command at any given time, it needs to consider only one selected
1428 frame at a time; this frame is what we call @dfn{the selected frame}
1429 in this manual. The display on which the selected frame is shown is
1430 the @dfn{selected frame's display}.
1432 @defun selected-frame
1433 This function returns the selected frame.
1436 Some window systems and window managers direct keyboard input to the
1437 window object that the mouse is in; others require explicit clicks or
1438 commands to @dfn{shift the focus} to various window objects. Either
1439 way, Emacs automatically keeps track of which frame has the focus. To
1440 explicitly switch to a different frame from a Lisp function, call
1441 @code{select-frame-set-input-focus}.
1443 Lisp programs can also switch frames ``temporarily'' by calling the
1444 function @code{select-frame}. This does not alter the window system's
1445 concept of focus; rather, it escapes from the window manager's control
1446 until that control is somehow reasserted.
1448 When using a text terminal, only one frame can be displayed at a time
1449 on the terminal, so after a call to @code{select-frame}, the next
1450 redisplay actually displays the newly selected frame. This frame
1451 remains selected until a subsequent call to @code{select-frame}. Each
1452 frame on a text terminal has a number which appears in the mode line
1453 before the buffer name (@pxref{Mode Line Variables}).
1455 @defun select-frame-set-input-focus frame &optional norecord
1456 This function selects @var{frame}, raises it (should it happen to be
1457 obscured by other frames) and tries to give it the X server's focus.
1458 On a text terminal, the next redisplay displays the new frame on the
1459 entire terminal screen. The optional argument @var{norecord} has the
1460 same meaning as for @code{select-frame} (see below). The return value
1461 of this function is not significant.
1464 @deffn Command select-frame frame &optional norecord
1465 This function selects frame @var{frame}, temporarily disregarding the
1466 focus of the X server if any. The selection of @var{frame} lasts until
1467 the next time the user does something to select a different frame, or
1468 until the next time this function is called. (If you are using a
1469 window system, the previously selected frame may be restored as the
1470 selected frame after return to the command loop, because it still may
1471 have the window system's input focus.)
1473 The specified @var{frame} becomes the selected frame, and its terminal
1474 becomes the selected terminal. This function then calls
1475 @code{select-window} as a subroutine, passing the window selected
1476 within @var{frame} as its first argument and @var{norecord} as its
1477 second argument (hence, if @var{norecord} is non-@code{nil}, this
1478 avoids changing the order of recently selected windows nor the buffer
1479 list). @xref{Selecting Windows}.
1481 This function returns @var{frame}, or @code{nil} if @var{frame} has
1484 In general, you should never use @code{select-frame} in a way that
1485 could switch to a different terminal without switching back when
1489 Emacs cooperates with the window system by arranging to select frames as
1490 the server and window manager request. It does so by generating a
1491 special kind of input event, called a @dfn{focus} event, when
1492 appropriate. The command loop handles a focus event by calling
1493 @code{handle-switch-frame}. @xref{Focus Events}.
1495 @deffn Command handle-switch-frame frame
1496 This function handles a focus event by selecting frame @var{frame}.
1498 Focus events normally do their job by invoking this command.
1499 Don't call it for any other reason.
1502 @defun redirect-frame-focus frame &optional focus-frame
1503 This function redirects focus from @var{frame} to @var{focus-frame}.
1504 This means that @var{focus-frame} will receive subsequent keystrokes and
1505 events intended for @var{frame}. After such an event, the value of
1506 @code{last-event-frame} will be @var{focus-frame}. Also, switch-frame
1507 events specifying @var{frame} will instead select @var{focus-frame}.
1509 If @var{focus-frame} is omitted or @code{nil}, that cancels any existing
1510 redirection for @var{frame}, which therefore once again receives its own
1513 One use of focus redirection is for frames that don't have minibuffers.
1514 These frames use minibuffers on other frames. Activating a minibuffer
1515 on another frame redirects focus to that frame. This puts the focus on
1516 the minibuffer's frame, where it belongs, even though the mouse remains
1517 in the frame that activated the minibuffer.
1519 Selecting a frame can also change focus redirections. Selecting frame
1520 @code{bar}, when @code{foo} had been selected, changes any redirections
1521 pointing to @code{foo} so that they point to @code{bar} instead. This
1522 allows focus redirection to work properly when the user switches from
1523 one frame to another using @code{select-window}.
1525 This means that a frame whose focus is redirected to itself is treated
1526 differently from a frame whose focus is not redirected.
1527 @code{select-frame} affects the former but not the latter.
1529 The redirection lasts until @code{redirect-frame-focus} is called to
1533 @defvar focus-in-hook
1534 This is a normal hook run when an Emacs frame gains input focus.
1537 @defvar focus-out-hook
1538 This is a normal hook run when an Emacs frame loses input focus.
1541 @defopt focus-follows-mouse
1542 This option is how you inform Emacs whether the window manager transfers
1543 focus when the user moves the mouse. Non-@code{nil} says that it does.
1544 When this is so, the command @code{other-frame} moves the mouse to a
1545 position consistent with the new selected frame.
1548 @node Visibility of Frames
1549 @section Visibility of Frames
1550 @cindex visible frame
1551 @cindex invisible frame
1552 @cindex iconified frame
1553 @cindex minimized frame
1554 @cindex frame visibility
1556 A frame on a graphical display may be @dfn{visible}, @dfn{invisible},
1557 or @dfn{iconified}. If it is visible, its contents are displayed in
1558 the usual manner. If it is iconified, its contents are not displayed,
1559 but there is a little icon somewhere to bring the frame back into view
1560 (some window managers refer to this state as @dfn{minimized} rather
1561 than @dfn{iconified}, but from Emacs' point of view they are the same
1562 thing). If a frame is invisible, it is not displayed at all.
1564 Visibility is meaningless on text terminals, since only the selected
1565 one is actually displayed in any case.
1567 @defun frame-visible-p frame
1568 This function returns the visibility status of frame @var{frame}. The
1569 value is @code{t} if @var{frame} is visible, @code{nil} if it is
1570 invisible, and @code{icon} if it is iconified.
1572 On a text terminal, all frames are considered ``visible'' for the
1573 purposes of this function, even though only one frame is displayed.
1574 @xref{Raising and Lowering}.
1577 @deffn Command iconify-frame &optional frame
1578 This function iconifies frame @var{frame}. If you omit @var{frame}, it
1579 iconifies the selected frame.
1582 @deffn Command make-frame-visible &optional frame
1583 This function makes frame @var{frame} visible. If you omit
1584 @var{frame}, it makes the selected frame visible. This does not raise
1585 the frame, but you can do that with @code{raise-frame} if you wish
1586 (@pxref{Raising and Lowering}).
1589 @deffn Command make-frame-invisible &optional frame force
1590 This function makes frame @var{frame} invisible. If you omit
1591 @var{frame}, it makes the selected frame invisible.
1593 Unless @var{force} is non-@code{nil}, this function refuses to make
1594 @var{frame} invisible if all other frames are invisible..
1597 The visibility status of a frame is also available as a frame
1598 parameter. You can read or change it as such. @xref{Management
1599 Parameters}. The user can also iconify and deiconify frames with the
1600 window manager. This happens below the level at which Emacs can exert
1601 any control, but Emacs does provide events that you can use to keep
1602 track of such changes. @xref{Misc Events}.
1604 @node Raising and Lowering
1605 @section Raising and Lowering Frames
1607 @cindex raising a frame
1608 @cindex lowering a frame
1609 Most window systems use a desktop metaphor. Part of this metaphor
1610 is the idea that system-level windows (e.g., Emacs frames) are
1611 stacked in a notional third dimension perpendicular to the screen
1612 surface. Where two overlap, the one higher up covers the one
1613 underneath. You can @dfn{raise} or @dfn{lower} a frame using the
1614 functions @code{raise-frame} and @code{lower-frame}.
1616 @deffn Command raise-frame &optional frame
1617 This function raises frame @var{frame} (default, the selected frame).
1618 If @var{frame} is invisible or iconified, this makes it visible.
1621 @deffn Command lower-frame &optional frame
1622 This function lowers frame @var{frame} (default, the selected frame).
1625 @defopt minibuffer-auto-raise
1626 If this is non-@code{nil}, activation of the minibuffer raises the frame
1627 that the minibuffer window is in.
1630 On window systems, you can also enable auto-raising (on frame
1631 selection) or auto-lowering (on frame deselection) using frame
1632 parameters. @xref{Management Parameters}.
1635 The concept of raising and lowering frames also applies to text
1636 terminal frames. On each text terminal, only the top frame is
1637 displayed at any one time.
1639 @defun tty-top-frame terminal
1640 This function returns the top frame on @var{terminal}. @var{terminal}
1641 should be a terminal object, a frame (meaning that frame's terminal),
1642 or @code{nil} (meaning the selected frame's terminal). If it does not
1643 refer to a text terminal, the return value is @code{nil}.
1646 @node Frame Configurations
1647 @section Frame Configurations
1648 @cindex frame configuration
1650 A @dfn{frame configuration} records the current arrangement of frames,
1651 all their properties, and the window configuration of each one.
1652 (@xref{Window Configurations}.)
1654 @defun current-frame-configuration
1655 This function returns a frame configuration list that describes
1656 the current arrangement of frames and their contents.
1659 @defun set-frame-configuration configuration &optional nodelete
1660 This function restores the state of frames described in
1661 @var{configuration}. However, this function does not restore deleted
1664 Ordinarily, this function deletes all existing frames not listed in
1665 @var{configuration}. But if @var{nodelete} is non-@code{nil}, the
1666 unwanted frames are iconified instead.
1669 @node Mouse Tracking
1670 @section Mouse Tracking
1671 @cindex mouse tracking
1672 @c @cindex tracking the mouse Duplicates track-mouse
1674 Sometimes it is useful to @dfn{track} the mouse, which means to display
1675 something to indicate where the mouse is and move the indicator as the
1676 mouse moves. For efficient mouse tracking, you need a way to wait until
1677 the mouse actually moves.
1679 The convenient way to track the mouse is to ask for events to represent
1680 mouse motion. Then you can wait for motion by waiting for an event. In
1681 addition, you can easily handle any other sorts of events that may
1682 occur. That is useful, because normally you don't want to track the
1683 mouse forever---only until some other event, such as the release of a
1686 @defspec track-mouse body@dots{}
1687 This special form executes @var{body}, with generation of mouse motion
1688 events enabled. Typically, @var{body} would use @code{read-event} to
1689 read the motion events and modify the display accordingly. @xref{Motion
1690 Events}, for the format of mouse motion events.
1692 The value of @code{track-mouse} is that of the last form in @var{body}.
1693 You should design @var{body} to return when it sees the up-event that
1694 indicates the release of the button, or whatever kind of event means
1695 it is time to stop tracking.
1698 The usual purpose of tracking mouse motion is to indicate on the screen
1699 the consequences of pushing or releasing a button at the current
1702 In many cases, you can avoid the need to track the mouse by using
1703 the @code{mouse-face} text property (@pxref{Special Properties}).
1704 That works at a much lower level and runs more smoothly than
1705 Lisp-level mouse tracking.
1708 @c These are not implemented yet.
1710 These functions change the screen appearance instantaneously. The
1711 effect is transient, only until the next ordinary Emacs redisplay. That
1712 is OK for mouse tracking, since it doesn't make sense for mouse tracking
1713 to change the text, and the body of @code{track-mouse} normally reads
1714 the events itself and does not do redisplay.
1716 @defun x-contour-region window beg end
1717 This function draws lines to make a box around the text from @var{beg}
1718 to @var{end}, in window @var{window}.
1721 @defun x-uncontour-region window beg end
1722 This function erases the lines that would make a box around the text
1723 from @var{beg} to @var{end}, in window @var{window}. Use it to remove
1724 a contour that you previously made by calling @code{x-contour-region}.
1727 @defun x-draw-rectangle frame left top right bottom
1728 This function draws a hollow rectangle on frame @var{frame} with the
1729 specified edge coordinates, all measured in pixels from the inside top
1730 left corner. It uses the cursor color, the one used for indicating the
1734 @defun x-erase-rectangle frame left top right bottom
1735 This function erases a hollow rectangle on frame @var{frame} with the
1736 specified edge coordinates, all measured in pixels from the inside top
1737 left corner. Erasure means redrawing the text and background that
1738 normally belong in the specified rectangle.
1742 @node Mouse Position
1743 @section Mouse Position
1744 @cindex mouse position
1745 @cindex position of mouse
1747 The functions @code{mouse-position} and @code{set-mouse-position}
1748 give access to the current position of the mouse.
1750 @defun mouse-position
1751 This function returns a description of the position of the mouse. The
1752 value looks like @code{(@var{frame} @var{x} . @var{y})}, where @var{x}
1753 and @var{y} are integers giving the position in characters relative to
1754 the top left corner of the inside of @var{frame}.
1757 @defvar mouse-position-function
1758 If non-@code{nil}, the value of this variable is a function for
1759 @code{mouse-position} to call. @code{mouse-position} calls this
1760 function just before returning, with its normal return value as the
1761 sole argument, and it returns whatever this function returns to it.
1763 This abnormal hook exists for the benefit of packages like
1764 @file{xt-mouse.el} that need to do mouse handling at the Lisp level.
1767 @defun set-mouse-position frame x y
1768 This function @dfn{warps the mouse} to position @var{x}, @var{y} in
1769 frame @var{frame}. The arguments @var{x} and @var{y} are integers,
1770 giving the position in characters relative to the top left corner of the
1771 inside of @var{frame}. If @var{frame} is not visible, this function
1772 does nothing. The return value is not significant.
1775 @defun mouse-pixel-position
1776 This function is like @code{mouse-position} except that it returns
1777 coordinates in units of pixels rather than units of characters.
1780 @defun set-mouse-pixel-position frame x y
1781 This function warps the mouse like @code{set-mouse-position} except that
1782 @var{x} and @var{y} are in units of pixels rather than units of
1783 characters. These coordinates are not required to be within the frame.
1785 If @var{frame} is not visible, this function does nothing. The return
1786 value is not significant.
1789 @defun frame-pointer-visible-p &optional frame
1790 This predicate function returns non-@code{nil} if the mouse pointer
1791 displayed on @var{frame} is visible; otherwise it returns @code{nil}.
1792 @var{frame} omitted or @code{nil} means the selected frame. This is
1793 useful when @code{make-pointer-invisible} is set to @code{t}: it
1794 allows to know if the pointer has been hidden.
1795 @xref{Mouse Avoidance,,,emacs, The Emacs Manual}.
1801 @section Pop-Up Menus
1803 A Lisp program can pop up a menu so that the user can choose an
1804 alternative with the mouse. On a text terminal, if the mouse is not
1805 available, the user can choose an alternative using the keyboard
1806 motion keys---@kbd{C-n}, @kbd{C-p}, or up- and down-arrow keys.
1808 @defun x-popup-menu position menu
1809 This function displays a pop-up menu and returns an indication of
1810 what selection the user makes.
1812 The argument @var{position} specifies where on the screen to put the
1813 top left corner of the menu. It can be either a mouse button event
1814 (which says to put the menu where the user actuated the button) or a
1818 ((@var{xoffset} @var{yoffset}) @var{window})
1822 where @var{xoffset} and @var{yoffset} are coordinates, measured in
1823 pixels, counting from the top left corner of @var{window}. @var{window}
1824 may be a window or a frame.
1826 If @var{position} is @code{t}, it means to use the current mouse
1827 position (or the top-left corner of the frame if the mouse is not
1828 available on a text terminal). If @var{position} is @code{nil}, it
1829 means to precompute the key binding equivalents for the keymaps
1830 specified in @var{menu}, without actually displaying or popping up the
1833 The argument @var{menu} says what to display in the menu. It can be a
1834 keymap or a list of keymaps (@pxref{Menu Keymaps}). In this case, the
1835 return value is the list of events corresponding to the user's choice.
1836 This list has more than one element if the choice occurred in a
1837 submenu. (Note that @code{x-popup-menu} does not actually execute the
1838 command bound to that sequence of events.) On text terminals and
1839 toolkits that support menu titles, the title is taken from the prompt
1840 string of @var{menu} if @var{menu} is a keymap, or from the prompt
1841 string of the first keymap in @var{menu} if it is a list of keymaps
1842 (@pxref{Defining Menus}).
1844 Alternatively, @var{menu} can have the following form:
1847 (@var{title} @var{pane1} @var{pane2}...)
1851 where each pane is a list of form
1854 (@var{title} @var{item1} @var{item2}...)
1857 Each @var{item} should be a cons cell, @code{(@var{line} . @var{value})},
1858 where @var{line} is a string and @var{value} is the value to return if
1859 that @var{line} is chosen. Unlike in a menu keymap, a @code{nil}
1860 @var{value} does not make the menu item non-selectable.
1861 Alternatively, each @var{item} can be a string rather than a cons
1862 cell; this makes a non-selectable menu item.
1864 If the user gets rid of the menu without making a valid choice, for
1865 instance by clicking the mouse away from a valid choice or by typing
1866 @kbd{C-g}, then this normally results in a quit and
1867 @code{x-popup-menu} does not return. But if @var{position} is a mouse
1868 button event (indicating that the user invoked the menu with the
1869 mouse) then no quit occurs and @code{x-popup-menu} returns @code{nil}.
1872 @strong{Usage note:} Don't use @code{x-popup-menu} to display a menu
1873 if you could do the job with a prefix key defined with a menu keymap.
1874 If you use a menu keymap to implement a menu, @kbd{C-h c} and @kbd{C-h
1875 a} can see the individual items in that menu and provide help for them.
1876 If instead you implement the menu by defining a command that calls
1877 @code{x-popup-menu}, the help facilities cannot know what happens inside
1878 that command, so they cannot give any help for the menu's items.
1880 The menu bar mechanism, which lets you switch between submenus by
1881 moving the mouse, cannot look within the definition of a command to see
1882 that it calls @code{x-popup-menu}. Therefore, if you try to implement a
1883 submenu using @code{x-popup-menu}, it cannot work with the menu bar in
1884 an integrated fashion. This is why all menu bar submenus are
1885 implemented with menu keymaps within the parent menu, and never with
1886 @code{x-popup-menu}. @xref{Menu Bar}.
1888 If you want a menu bar submenu to have contents that vary, you should
1889 still use a menu keymap to implement it. To make the contents vary, add
1890 a hook function to @code{menu-bar-update-hook} to update the contents of
1891 the menu keymap as necessary.
1894 @section Dialog Boxes
1895 @cindex dialog boxes
1897 A dialog box is a variant of a pop-up menu---it looks a little
1898 different, it always appears in the center of a frame, and it has just
1899 one level and one or more buttons. The main use of dialog boxes is
1900 for asking questions that the user can answer with ``yes'', ``no'',
1901 and a few other alternatives. With a single button, they can also
1902 force the user to acknowledge important information. The functions
1903 @code{y-or-n-p} and @code{yes-or-no-p} use dialog boxes instead of the
1904 keyboard, when called from commands invoked by mouse clicks.
1906 @defun x-popup-dialog position contents &optional header
1907 This function displays a pop-up dialog box and returns an indication of
1908 what selection the user makes. The argument @var{contents} specifies
1909 the alternatives to offer; it has this format:
1912 (@var{title} (@var{string} . @var{value})@dots{})
1916 which looks like the list that specifies a single pane for
1917 @code{x-popup-menu}.
1919 The return value is @var{value} from the chosen alternative.
1921 As for @code{x-popup-menu}, an element of the list may be just a
1922 string instead of a cons cell @code{(@var{string} . @var{value})}.
1923 That makes a box that cannot be selected.
1925 If @code{nil} appears in the list, it separates the left-hand items from
1926 the right-hand items; items that precede the @code{nil} appear on the
1927 left, and items that follow the @code{nil} appear on the right. If you
1928 don't include a @code{nil} in the list, then approximately half the
1929 items appear on each side.
1931 Dialog boxes always appear in the center of a frame; the argument
1932 @var{position} specifies which frame. The possible values are as in
1933 @code{x-popup-menu}, but the precise coordinates or the individual
1934 window don't matter; only the frame matters.
1936 If @var{header} is non-@code{nil}, the frame title for the box is
1937 @samp{Information}, otherwise it is @samp{Question}. The former is used
1938 for @code{message-box} (@pxref{message-box}). (On text terminals, the
1939 box title is not displayed.)
1941 In some configurations, Emacs cannot display a real dialog box; so
1942 instead it displays the same items in a pop-up menu in the center of the
1945 If the user gets rid of the dialog box without making a valid choice,
1946 for instance using the window manager, then this produces a quit and
1947 @code{x-popup-dialog} does not return.
1951 @section Pointer Shape
1952 @cindex pointer shape
1953 @cindex mouse pointer shape
1955 You can specify the mouse pointer style for particular text or
1956 images using the @code{pointer} text property, and for images with the
1957 @code{:pointer} and @code{:map} image properties. The values you can
1958 use in these properties are @code{text} (or @code{nil}), @code{arrow},
1959 @code{hand}, @code{vdrag}, @code{hdrag}, @code{modeline}, and
1960 @code{hourglass}. @code{text} stands for the usual mouse pointer
1961 style used over text.
1963 Over void parts of the window (parts that do not correspond to any
1964 of the buffer contents), the mouse pointer usually uses the
1965 @code{arrow} style, but you can specify a different style (one of
1966 those above) by setting @code{void-text-area-pointer}.
1968 @defopt void-text-area-pointer
1969 This variable specifies the mouse pointer style for void text areas.
1970 These include the areas after the end of a line or below the last line
1971 in the buffer. The default is to use the @code{arrow} (non-text)
1975 When using X, you can specify what the @code{text} pointer style
1976 really looks like by setting the variable @code{x-pointer-shape}.
1978 @defvar x-pointer-shape
1979 This variable specifies the pointer shape to use ordinarily in the
1980 Emacs frame, for the @code{text} pointer style.
1983 @defvar x-sensitive-text-pointer-shape
1984 This variable specifies the pointer shape to use when the mouse
1985 is over mouse-sensitive text.
1988 These variables affect newly created frames. They do not normally
1989 affect existing frames; however, if you set the mouse color of a
1990 frame, that also installs the current value of those two variables.
1991 @xref{Font and Color Parameters}.
1993 The values you can use, to specify either of these pointer shapes, are
1994 defined in the file @file{lisp/term/x-win.el}. Use @kbd{M-x apropos
1995 @key{RET} x-pointer @key{RET}} to see a list of them.
1997 @node Window System Selections
1998 @section Window System Selections
1999 @cindex selection (for window systems)
2001 @cindex primary selection
2002 @cindex secondary selection
2004 In the X window system, data can be transferred between different
2005 applications by means of @dfn{selections}. X defines an arbitrary
2006 number of @dfn{selection types}, each of which can store its own data;
2007 however, only three are commonly used: the @dfn{clipboard},
2008 @dfn{primary selection}, and @dfn{secondary selection}. @xref{Cut and
2009 Paste,, Cut and Paste, emacs, The GNU Emacs Manual}, for Emacs
2010 commands that make use of these selections. This section documents
2011 the low-level functions for reading and setting X selections.
2013 @deffn Command x-set-selection type data
2014 This function sets an X selection. It takes two arguments: a
2015 selection type @var{type}, and the value to assign to it, @var{data}.
2017 @var{type} should be a symbol; it is usually one of @code{PRIMARY},
2018 @code{SECONDARY} or @code{CLIPBOARD}. These are symbols with
2019 upper-case names, in accord with X Window System conventions. If
2020 @var{type} is @code{nil}, that stands for @code{PRIMARY}.
2022 If @var{data} is @code{nil}, it means to clear out the selection.
2023 Otherwise, @var{data} may be a string, a symbol, an integer (or a cons
2024 of two integers or list of two integers), an overlay, or a cons of two
2025 markers pointing to the same buffer. An overlay or a pair of markers
2026 stands for text in the overlay or between the markers. The argument
2027 @var{data} may also be a vector of valid non-vector selection values.
2029 This function returns @var{data}.
2032 @defun x-get-selection &optional type data-type
2033 This function accesses selections set up by Emacs or by other X
2034 clients. It takes two optional arguments, @var{type} and
2035 @var{data-type}. The default for @var{type}, the selection type, is
2038 The @var{data-type} argument specifies the form of data conversion to
2039 use, to convert the raw data obtained from another X client into Lisp
2040 data. Meaningful values include @code{TEXT}, @code{STRING},
2041 @code{UTF8_STRING}, @code{TARGETS}, @code{LENGTH}, @code{DELETE},
2042 @code{FILE_NAME}, @code{CHARACTER_POSITION}, @code{NAME},
2043 @code{LINE_NUMBER}, @code{COLUMN_NUMBER}, @code{OWNER_OS},
2044 @code{HOST_NAME}, @code{USER}, @code{CLASS}, @code{ATOM}, and
2045 @code{INTEGER}. (These are symbols with upper-case names in accord
2046 with X conventions.) The default for @var{data-type} is
2050 @defopt selection-coding-system
2051 This variable specifies the coding system to use when reading and
2052 writing selections or the clipboard. @xref{Coding
2053 Systems}. The default is @code{compound-text-with-extensions}, which
2054 converts to the text representation that X11 normally uses.
2057 @cindex clipboard support (for MS-Windows)
2058 When Emacs runs on MS-Windows, it does not implement X selections in
2059 general, but it does support the clipboard. @code{x-get-selection}
2060 and @code{x-set-selection} on MS-Windows support the text data type
2061 only; if the clipboard holds other types of data, Emacs treats the
2065 @section Drag and Drop
2067 @vindex x-dnd-test-function
2068 @vindex x-dnd-known-types
2069 When a user drags something from another application over Emacs, that other
2070 application expects Emacs to tell it if Emacs can handle the data that is
2071 dragged. The variable @code{x-dnd-test-function} is used by Emacs to determine
2072 what to reply. The default value is @code{x-dnd-default-test-function}
2073 which accepts drops if the type of the data to be dropped is present in
2074 @code{x-dnd-known-types}. You can customize @code{x-dnd-test-function} and/or
2075 @code{x-dnd-known-types} if you want Emacs to accept or reject drops based
2076 on some other criteria.
2078 @vindex x-dnd-types-alist
2079 If you want to change the way Emacs handles drop of different types
2080 or add a new type, customize @code{x-dnd-types-alist}. This requires
2081 detailed knowledge of what types other applications use for drag and
2084 @vindex dnd-protocol-alist
2085 When an URL is dropped on Emacs it may be a file, but it may also be
2086 another URL type (ftp, http, etc.). Emacs first checks
2087 @code{dnd-protocol-alist} to determine what to do with the URL@. If
2088 there is no match there and if @code{browse-url-browser-function} is
2089 an alist, Emacs looks for a match there. If no match is found the
2090 text for the URL is inserted. If you want to alter Emacs behavior,
2091 you can customize these variables.
2094 @section Color Names
2097 @cindex specify color
2098 @cindex numerical RGB color specification
2099 A color name is text (usually in a string) that specifies a color.
2100 Symbolic names such as @samp{black}, @samp{white}, @samp{red}, etc.,
2101 are allowed; use @kbd{M-x list-colors-display} to see a list of
2102 defined names. You can also specify colors numerically in forms such
2103 as @samp{#@var{rgb}} and @samp{RGB:@var{r}/@var{g}/@var{b}}, where
2104 @var{r} specifies the red level, @var{g} specifies the green level,
2105 and @var{b} specifies the blue level. You can use either one, two,
2106 three, or four hex digits for @var{r}; then you must use the same
2107 number of hex digits for all @var{g} and @var{b} as well, making
2108 either 3, 6, 9 or 12 hex digits in all. (See the documentation of the
2109 X Window System for more details about numerical RGB specification of
2112 These functions provide a way to determine which color names are
2113 valid, and what they look like. In some cases, the value depends on the
2114 @dfn{selected frame}, as described below; see @ref{Input Focus}, for the
2115 meaning of the term ``selected frame''.
2117 To read user input of color names with completion, use
2118 @code{read-color} (@pxref{High-Level Completion, read-color}).
2120 @defun color-defined-p color &optional frame
2121 This function reports whether a color name is meaningful. It returns
2122 @code{t} if so; otherwise, @code{nil}. The argument @var{frame} says
2123 which frame's display to ask about; if @var{frame} is omitted or
2124 @code{nil}, the selected frame is used.
2126 Note that this does not tell you whether the display you are using
2127 really supports that color. When using X, you can ask for any defined
2128 color on any kind of display, and you will get some result---typically,
2129 the closest it can do. To determine whether a frame can really display
2130 a certain color, use @code{color-supported-p} (see below).
2132 @findex x-color-defined-p
2133 This function used to be called @code{x-color-defined-p},
2134 and that name is still supported as an alias.
2137 @defun defined-colors &optional frame
2138 This function returns a list of the color names that are defined
2139 and supported on frame @var{frame} (default, the selected frame).
2140 If @var{frame} does not support colors, the value is @code{nil}.
2142 @findex x-defined-colors
2143 This function used to be called @code{x-defined-colors},
2144 and that name is still supported as an alias.
2147 @defun color-supported-p color &optional frame background-p
2148 This returns @code{t} if @var{frame} can really display the color
2149 @var{color} (or at least something close to it). If @var{frame} is
2150 omitted or @code{nil}, the question applies to the selected frame.
2152 Some terminals support a different set of colors for foreground and
2153 background. If @var{background-p} is non-@code{nil}, that means you are
2154 asking whether @var{color} can be used as a background; otherwise you
2155 are asking whether it can be used as a foreground.
2157 The argument @var{color} must be a valid color name.
2160 @defun color-gray-p color &optional frame
2161 This returns @code{t} if @var{color} is a shade of gray, as defined on
2162 @var{frame}'s display. If @var{frame} is omitted or @code{nil}, the
2163 question applies to the selected frame. If @var{color} is not a valid
2164 color name, this function returns @code{nil}.
2167 @defun color-values color &optional frame
2169 This function returns a value that describes what @var{color} should
2170 ideally look like on @var{frame}. If @var{color} is defined, the
2171 value is a list of three integers, which give the amount of red, the
2172 amount of green, and the amount of blue. Each integer ranges in
2173 principle from 0 to 65535, but some displays may not use the full
2174 range. This three-element list is called the @dfn{rgb values} of the
2177 If @var{color} is not defined, the value is @code{nil}.
2180 (color-values "black")
2182 (color-values "white")
2183 @result{} (65280 65280 65280)
2184 (color-values "red")
2185 @result{} (65280 0 0)
2186 (color-values "pink")
2187 @result{} (65280 49152 51968)
2188 (color-values "hungry")
2192 The color values are returned for @var{frame}'s display. If
2193 @var{frame} is omitted or @code{nil}, the information is returned for
2194 the selected frame's display. If the frame cannot display colors, the
2195 value is @code{nil}.
2197 @findex x-color-values
2198 This function used to be called @code{x-color-values},
2199 and that name is still supported as an alias.
2202 @node Text Terminal Colors
2203 @section Text Terminal Colors
2204 @cindex colors on text terminals
2206 Text terminals usually support only a small number of colors, and
2207 the computer uses small integers to select colors on the terminal.
2208 This means that the computer cannot reliably tell what the selected
2209 color looks like; instead, you have to inform your application which
2210 small integers correspond to which colors. However, Emacs does know
2211 the standard set of colors and will try to use them automatically.
2213 The functions described in this section control how terminal colors
2216 Several of these functions use or return @dfn{rgb values}, described
2217 in @ref{Color Names}.
2219 These functions accept a display (either a frame or the name of a
2220 terminal) as an optional argument. We hope in the future to make
2221 Emacs support different colors on different text terminals; then this
2222 argument will specify which terminal to operate on (the default being
2223 the selected frame's terminal; @pxref{Input Focus}). At present,
2224 though, the @var{frame} argument has no effect.
2226 @defun tty-color-define name number &optional rgb frame
2227 This function associates the color name @var{name} with
2228 color number @var{number} on the terminal.
2230 The optional argument @var{rgb}, if specified, is an rgb value, a list
2231 of three numbers that specify what the color actually looks like.
2232 If you do not specify @var{rgb}, then this color cannot be used by
2233 @code{tty-color-approximate} to approximate other colors, because
2234 Emacs will not know what it looks like.
2237 @defun tty-color-clear &optional frame
2238 This function clears the table of defined colors for a text terminal.
2241 @defun tty-color-alist &optional frame
2242 This function returns an alist recording the known colors supported by
2245 Each element has the form @code{(@var{name} @var{number} . @var{rgb})}
2246 or @code{(@var{name} @var{number})}. Here, @var{name} is the color
2247 name, @var{number} is the number used to specify it to the terminal.
2248 If present, @var{rgb} is a list of three color values (for red, green,
2249 and blue) that says what the color actually looks like.
2252 @defun tty-color-approximate rgb &optional frame
2253 This function finds the closest color, among the known colors
2254 supported for @var{display}, to that described by the rgb value
2255 @var{rgb} (a list of color values). The return value is an element of
2256 @code{tty-color-alist}.
2259 @defun tty-color-translate color &optional frame
2260 This function finds the closest color to @var{color} among the known
2261 colors supported for @var{display} and returns its index (an integer).
2262 If the name @var{color} is not defined, the value is @code{nil}.
2266 @section X Resources
2268 This section describes some of the functions and variables for
2269 querying and using X resources, or their equivalent on your operating
2270 system. @xref{X Resources,, X Resources, emacs, The GNU Emacs
2271 Manual}, for more information about X resources.
2273 @defun x-get-resource attribute class &optional component subclass
2274 The function @code{x-get-resource} retrieves a resource value from the X
2275 Window defaults database.
2277 Resources are indexed by a combination of a @dfn{key} and a @dfn{class}.
2278 This function searches using a key of the form
2279 @samp{@var{instance}.@var{attribute}} (where @var{instance} is the name
2280 under which Emacs was invoked), and using @samp{Emacs.@var{class}} as
2283 The optional arguments @var{component} and @var{subclass} add to the key
2284 and the class, respectively. You must specify both of them or neither.
2285 If you specify them, the key is
2286 @samp{@var{instance}.@var{component}.@var{attribute}}, and the class is
2287 @samp{Emacs.@var{class}.@var{subclass}}.
2290 @defvar x-resource-class
2291 This variable specifies the application name that @code{x-get-resource}
2292 should look up. The default value is @code{"Emacs"}. You can examine X
2293 resources for application names other than ``Emacs'' by binding this
2294 variable to some other string, around a call to @code{x-get-resource}.
2297 @defvar x-resource-name
2298 This variable specifies the instance name that @code{x-get-resource}
2299 should look up. The default value is the name Emacs was invoked with,
2300 or the value specified with the @samp{-name} or @samp{-rn} switches.
2303 To illustrate some of the above, suppose that you have the line:
2306 xterm.vt100.background: yellow
2310 in your X resources file (whose name is usually @file{~/.Xdefaults}
2311 or @file{~/.Xresources}). Then:
2315 (let ((x-resource-class "XTerm") (x-resource-name "xterm"))
2316 (x-get-resource "vt100.background" "VT100.Background"))
2320 (let ((x-resource-class "XTerm") (x-resource-name "xterm"))
2321 (x-get-resource "background" "VT100" "vt100" "Background"))
2326 @defvar inhibit-x-resources
2327 If this variable is non-@code{nil}, Emacs does not look up X
2328 resources, and X resources do not have any effect when creating new
2332 @node Display Feature Testing
2333 @section Display Feature Testing
2334 @cindex display feature testing
2336 The functions in this section describe the basic capabilities of a
2337 particular display. Lisp programs can use them to adapt their behavior
2338 to what the display can do. For example, a program that ordinarily uses
2339 a popup menu could use the minibuffer if popup menus are not supported.
2341 The optional argument @var{display} in these functions specifies which
2342 display to ask the question about. It can be a display name, a frame
2343 (which designates the display that frame is on), or @code{nil} (which
2344 refers to the selected frame's display, @pxref{Input Focus}).
2346 @xref{Color Names}, @ref{Text Terminal Colors}, for other functions to
2347 obtain information about displays.
2349 @defun display-popup-menus-p &optional display
2350 This function returns @code{t} if popup menus are supported on
2351 @var{display}, @code{nil} if not. Support for popup menus requires
2352 that the mouse be available, since the menu is popped up by clicking
2353 the mouse on some portion of the Emacs display.
2356 @defun display-graphic-p &optional display
2357 This function returns @code{t} if @var{display} is a graphic display
2358 capable of displaying several frames and several different fonts at
2359 once. This is true for displays that use a window system such as X,
2360 and false for text terminals.
2363 @defun display-mouse-p &optional display
2364 @cindex mouse, availability
2365 This function returns @code{t} if @var{display} has a mouse available,
2369 @defun display-color-p &optional display
2370 @findex x-display-color-p
2371 This function returns @code{t} if the screen is a color screen.
2372 It used to be called @code{x-display-color-p}, and that name
2373 is still supported as an alias.
2376 @defun display-grayscale-p &optional display
2377 This function returns @code{t} if the screen can display shades of gray.
2378 (All color displays can do this.)
2381 @defun display-supports-face-attributes-p attributes &optional display
2382 @anchor{Display Face Attribute Testing}
2383 This function returns non-@code{nil} if all the face attributes in
2384 @var{attributes} are supported (@pxref{Face Attributes}).
2386 The definition of `supported' is somewhat heuristic, but basically
2387 means that a face containing all the attributes in @var{attributes},
2388 when merged with the default face for display, can be represented in a
2393 different in appearance than the default face, and
2396 `close in spirit' to what the attributes specify, if not exact.
2399 Point (2) implies that a @code{:weight black} attribute will be
2400 satisfied by any display that can display bold, as will
2401 @code{:foreground "yellow"} as long as some yellowish color can be
2402 displayed, but @code{:slant italic} will @emph{not} be satisfied by
2403 the tty display code's automatic substitution of a `dim' face for
2407 @defun display-selections-p &optional display
2408 This function returns @code{t} if @var{display} supports selections.
2409 Windowed displays normally support selections, but they may also be
2410 supported in some other cases.
2413 @defun display-images-p &optional display
2414 This function returns @code{t} if @var{display} can display images.
2415 Windowed displays ought in principle to handle images, but some
2416 systems lack the support for that. On a display that does not support
2417 images, Emacs cannot display a tool bar.
2420 @defun display-screens &optional display
2421 This function returns the number of screens associated with the display.
2424 @c FIXME: Document `x-display-pixel-{width, height}'?
2425 @defun display-pixel-height &optional display
2426 This function returns the height of the screen in pixels.
2427 On a character terminal, it gives the height in characters.
2429 For graphical terminals, note that on ``multi-monitor'' setups this
2430 refers to the pixel height for all physical monitors associated with
2431 @var{display}. @xref{Multiple Terminals}.
2434 @defun display-pixel-width &optional display
2435 This function returns the width of the screen in pixels.
2436 On a character terminal, it gives the width in characters.
2438 For graphical terminals, note that on ``multi-monitor'' setups this
2439 refers to the pixel width for all physical monitors associated with
2440 @var{display}. @xref{Multiple Terminals}.
2443 @c FIXME: Document `x-display-mm-{width, height}'?
2444 @defun display-mm-height &optional display
2445 This function returns the height of the screen in millimeters,
2446 or @code{nil} if Emacs cannot get that information.
2448 For graphical terminals, note that on ``multi-monitor'' setups this
2449 refers to the height for all physical monitors associated with
2450 @var{display}. @xref{Multiple Terminals}.
2453 @defun display-mm-width &optional display
2454 This function returns the width of the screen in millimeters,
2455 or @code{nil} if Emacs cannot get that information.
2457 For graphical terminals, note that on ``multi-monitor'' setups this
2458 refers to the width for all physical monitors associated with
2459 @var{display}. @xref{Multiple Terminals}.
2462 @defopt display-mm-dimensions-alist
2463 This variable allows the user to specify the dimensions of graphical
2464 displays returned by @code{display-mm-height} and
2465 @code{display-mm-width} in case the system provides incorrect values.
2468 @cindex backing store
2469 @defun display-backing-store &optional display
2470 This function returns the backing store capability of the display.
2471 Backing store means recording the pixels of windows (and parts of
2472 windows) that are not exposed, so that when exposed they can be
2473 displayed very quickly.
2475 Values can be the symbols @code{always}, @code{when-mapped}, or
2476 @code{not-useful}. The function can also return @code{nil}
2477 when the question is inapplicable to a certain kind of display.
2480 @cindex SaveUnder feature
2481 @defun display-save-under &optional display
2482 This function returns non-@code{nil} if the display supports the
2483 SaveUnder feature. That feature is used by pop-up windows
2484 to save the pixels they obscure, so that they can pop down
2488 @defun display-planes &optional display
2489 This function returns the number of planes the display supports.
2490 This is typically the number of bits per pixel.
2491 For a tty display, it is log to base two of the number of colors supported.
2494 @defun display-visual-class &optional display
2495 This function returns the visual class for the screen. The value is
2496 one of the symbols @code{static-gray} (a limited, unchangeable number
2497 of grays), @code{gray-scale} (a full range of grays),
2498 @code{static-color} (a limited, unchangeable number of colors),
2499 @code{pseudo-color} (a limited number of colors), @code{true-color} (a
2500 full range of colors), and @code{direct-color} (a full range of
2504 @defun display-color-cells &optional display
2505 This function returns the number of color cells the screen supports.
2508 These functions obtain additional information specifically
2511 @defun x-server-version &optional display
2512 This function returns the list of version numbers of the X server
2513 running the display. The value is a list of three integers: the major
2514 and minor version numbers of the X protocol, and the
2515 distributor-specific release number of the X server software itself.
2518 @defun x-server-vendor &optional display
2519 This function returns the ``vendor'' that provided the X server
2520 software (as a string). Really this means whoever distributes the X
2523 When the developers of X labeled software distributors as
2524 ``vendors'', they showed their false assumption that no system could
2525 ever be developed and distributed noncommercially.
2529 @defvar x-no-window-manager
2530 This variable's value is @code{t} if no X window manager is in use.
2536 The functions @code{x-pixel-width} and @code{x-pixel-height} return the
2537 width and height of an X Window frame, measured in pixels.