@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998 Free Software Foundation, Inc.
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2002
+@c Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/frames
@node Frames, Positions, Windows, Top
@cindex window frame
When Emacs communicates directly with a supported window system, such
-as X Windows, it does not have a terminal frame; instead, it starts with
+as X, it does not have a terminal frame; instead, it starts with
a single @dfn{window frame}, but you can create more, and Emacs can
display several such frames at once as is usual for window systems.
* Color Names:: Getting the definitions of color names.
* Text Terminal Colors:: Defining colors for text-only terminals.
* Resources:: Getting resource values from the server.
-* Server Data:: Getting info about the X server.
+* Display Feature Testing:: Determining the features of a terminal.
@end menu
@xref{Display}, for information about the related topic of
@end defun
@defvar before-make-frame-hook
-@tindex before-make-frame-hook
A normal hook run by @code{make-frame} before it actually creates the
frame.
@end defvar
@defvar after-make-frame-functions
@tindex after-make-frame-functions
An abnormal hook run by @code{make-frame} after it creates the frame.
-Each function in @code{after-make-frame-hook} receives one argument, the
+Each function in @code{after-make-frame-functions} receives one argument, the
frame just created.
@end defvar
the @code{display} frame parameter when you create the frame.
Emacs treats each X server as a separate terminal, giving each one its
-own selected frame and its own minibuffer windows.
+own selected frame and its own minibuffer windows. However, only one of
+those frames is ``@emph{the} selected frame'' at any given moment, see
+@ref{Input Focus}.
A few Lisp variables are @dfn{terminal-local}; that is, they have a
separate binding for each terminal. The binding in effect at any time
a display name.
@end defun
-@defun x-open-connection display &optional xrm-string
+@defun x-open-connection display &optional xrm-string must-succeed
This function opens a connection to the X display @var{display}. It
does not create a frame on that display, but it permits you to check
that communication can be established with that display.
@end example
@xref{Resources}.
+
+If @var{must-succeed} is non-@code{nil}, failure to open the connection
+terminates Emacs. Otherwise, it is an ordinary Lisp error.
@end defun
@defun x-close-connection display
These functions let you read and change the parameter values of a
frame.
+@defun frame-parameter frame parameter
+@tindex frame-parameter
+This function returns the value of the parameter named @var{parameter}
+of @var{frame}. If @var{frame} is @code{nil}, it returns the
+selected frame's parameter.
+@end defun
+
@defun frame-parameters frame
The function @code{frame-parameters} returns an alist listing all the
parameters of @var{frame} and their values.
the frame appear with the wrong ones and then change to the specified
ones. If that bothers you, you can specify the same geometry and
appearance with X resources; those do take effect before the frame is
-created. @xref{Resources X,, X Resources, emacs, The GNU Emacs Manual}.
+created. @xref{X Resources,, X Resources, emacs, The GNU Emacs Manual}.
X resource settings typically apply to all frames. If you want to
specify some X resources solely for the sake of the initial frame, and
uses. Here is a table of the parameters that have special meanings in a
window frame; of these, @code{name}, @code{title}, @code{height},
@code{width}, @code{buffer-list} and @code{buffer-predicate} provide
-meaningful information in terminal frames.
+meaningful information in terminal frames, and @code{tty-color-mode}
+is meaningful @emph{only} in terminal frames.
@table @code
@item display
The width of the frame contents, in characters. (To get the height in
pixels, call @code{frame-pixel-width}; see @ref{Size and Position}.)
+@item fullscreen
+Specify that width, height or both shall be set to the size of the screen.
+The value @code{fullwidth} specifies that width shall be the size of the
+screen. The value @code{fullheight} specifies that height shall be the
+size of the screen. The value @code{fullboth} specifies that both the
+width and the height shall be set to the size of the screen.
+
@item window-id
The number of the window-system window used by the frame
to contain the actual Emacs windows.
@item font
The name of the font for displaying text in the frame. This is a
string, either a valid font name for your system or the name of an Emacs
-fontset (@pxref{Fontsets}). Changing this frame parameter on a frame,
+fontset (@pxref{Fontsets}). Changing this frame parameter on a frame
also changes the font-related attributes of the default face on that
frame.
to changing the background color of face @code{mouse}.
@item cursor-color
-The color for the cursor that shows point. Changing this parameter is
+The color for the cursor that shows point. Changing this parameter is
equivalent to changing the background color of face @code{cursor}.
@item border-color
-The color for the border of the frame. Changing this parameter is
+The color for the border of the frame. Changing this parameter is
equivalent to changing the background color of face @code{border}.
+@item tty-color-mode
+@cindex standard colors for character terminals
+This parameter overrides the terminal's color support as given by the
+system's terminal capabilities database in that this parameter's value
+specifies the color mode to use in terminal frames. The value can be
+either a symbol or a number. A number specifies the number of colors
+to use (and, indirectly, what commands to issue to produce each
+color). For example, @code{(tty-color-mode . 8)} forces Emacs to use
+the ANSI escape sequences for 8 standard text colors; and a value of
+-1 means Emacs should turn off color support. If the parameter's
+value is a symbol, that symbol is looked up in the alist
+@code{tty-color-mode-alist}, and if found, the associated number is
+used as the color support mode.
+
@item scroll-bar-foreground
If non-@code{nil}, the color for the foreground of scroll bars.
Changing this parameter is equivalent to setting the foreground color of
@item scroll-bar-background
If non-@code{nil}, the color for the background of scroll bars.
-Changing this parameter is equivalent to setting the foreground color of
+Changing this parameter is equivalent to setting the background color of
face @code{scroll-bar}.
@item display-type
@code{box}, and @code{(bar . @var{width})}. The symbol @code{box}
specifies an ordinary black box overlaying the character after point;
that is the default. The symbol @code{bar} specifies a vertical bar
-between characters as the cursor. @code{(bar . @var{width})} specifies
-a bar @var{width} pixels wide.
+between characters as the cursor. @code{(bar . @var{width})}
+specifies a bar @var{width} pixels wide. The symbol @code{hbar}
+specifies a horizontal bar, an underscore-like cursor. @code{(hbar .
+@var{width})} specifiles a horizontal bar @var{width} pixels high.
+
+@vindex cursor-type
+The buffer-local variable @code{cursor-type} overrides the value of
+the @code{cursor-type} frame parameter, and can in addition have
+values @code{t} (use the cursor specified for the frame) and
+@code{nil} (don't display a cursor).
@item border-width
The width in pixels of the window border.
number you specify is whether it is greater than zero.)
@item screen-gamma
-If this is a number, Emacs performs ``gamma correction'' on colors. The
-value should be the screen gamma of your display, a floating point
-number. Usual PC monitors have a screen gamma of 2.2. Smaller values
-result in darker colors; you might want to try a screen gamma of 1.5 for
-LCD color displays. The viewing gamma Emacs uses is 0.4545 (1/2.2).
+@cindex gamma correction
+If this is a number, Emacs performs ``gamma correction'' which adjusts
+the brightness of all colors. The value should be the screen gamma of
+your display, a floating point number.
+
+Usual PC monitors have a screen gamma of 2.2, so color values in
+Emacs, and in X windows generally, are calibrated to display properly
+on a monitor with that gamma value. If you specify 2.2 for
+@code{screen-gamma}, that means no correction is needed. Other values
+request correction, designed to make the corrected colors appear on
+your screen they way they would have appeared without correction on an
+ordinary monitor with a gamma value of 2.2.
+
+If your monitor displays colors too light, you should specify a
+@code{screen-gamma} value smaller than 2.2. This requests correction
+that makes colors darker. A screen gamma value of 1.5 may give good
+results for LCD color displays.
@item tool-bar-lines
The number of lines to use for the toolbar. A value of @code{nil} means
don't display a tool bar.
+@item line-spacing
+Additional space put below text lines in pixels (a positive integer).
+
@ignore
@item parent-id
@c ??? Not yet working.
@code{width}. Whatever geometry parameters you don't specify are chosen
by the window manager in its usual fashion.
- Here are some special features for working with sizes and positions:
+ Here are some special features for working with sizes and positions.
+(For the precise meaning of ``selected frame'' used by these functions,
+see @ref{Input Focus}.)
@defun set-frame-position frame left top
This function sets the position of the top left corner of @var{frame} to
configuration (@pxref{Frame Configurations}); this is similar to the
way windows behave.
-@deffn Command delete-frame &optional frame
-This function deletes the frame @var{frame}. By default, @var{frame} is
-the selected frame.
+@deffn Command delete-frame &optional frame force
+@vindex delete-frame-hook
+This function deletes the frame @var{frame} after running the hook
+@code{delete-frame-hook}. By default, @var{frame} is the selected
+frame.
+
+A frame cannot be deleted if its minibuffer is used by other frames.
+Normally, you cannot delete a frame if all other frames are invisible,
+but if the @var{force} is non-@code{nil}, then you are allowed to do so.
@end deffn
@defun frame-live-p frame
@defun frame-list
The function @code{frame-list} returns a list of all the frames that
have not been deleted. It is analogous to @code{buffer-list} for
-buffers. The list that you get is newly created, so modifying the list
-doesn't have any effect on the internals of Emacs.
+buffers, and includes frames on all terminals. The list that you get is
+newly created, so modifying the list doesn't have any effect on the
+internals of Emacs.
@end defun
@defun visible-frame-list
@defun next-frame &optional frame minibuf
The function @code{next-frame} lets you cycle conveniently through all
-the frames from an arbitrary starting point. It returns the ``next''
-frame after @var{frame} in the cycle. If @var{frame} is omitted or
-@code{nil}, it defaults to the selected frame.
+the frames on the current display from an arbitrary starting point. It
+returns the ``next'' frame after @var{frame} in the cycle. If
+@var{frame} is omitted or @code{nil}, it defaults to the selected frame
+(@pxref{Input Focus}).
The second argument, @var{minibuf}, says which frames to consider:
At any time, one frame in Emacs is the @dfn{selected frame}. The selected
window always resides on the selected frame.
+When Emacs displays its frames on several terminals (@pxref{Multiple
+Displays}), each terminal has its own selected frame. But only one of
+these is ``@emph{the} selected frame'': it's the frame that belongs to
+the terminal from which the most recent input came. That is, when Emacs
+runs a command that came from a certain terminal, the selected frame is
+the one of that terminal. Since Emacs runs only a single command at any
+given time, it needs to consider only one selected frame at a time; this
+frame is what we call @dfn{the selected frame} in this manual. The
+display on which the selected frame is displayed is the @dfn{selected
+frame's display}.
+
@defun selected-frame
This function returns the selected frame.
@end defun
This function selects frame @var{frame}, temporarily disregarding the
focus of the X server if any. The selection of @var{frame} lasts until
the next time the user does something to select a different frame, or
-until the next time this function is called.
+until the next time this function is called. The specified @var{frame}
+becomes the selected frame, as explained above, and the terminal that
+@var{frame} is on becomes the selected terminal.
+
+In general, you should never use @code{select-frame} in a way that could
+switch to a different terminal without switching back when you're done.
@end defun
Emacs cooperates with the window system by arranging to select frames as
@end defun
@defopt focus-follows-mouse
-@tindex focus-follows-mouse
This option is how you inform Emacs whether the window manager transfers
focus when the user moves the mouse. Non-@code{nil} says that it does.
When this is so, the command @code{other-frame} moves the mouse to a
the current arrangement of frames and their contents.
@end defun
-@defun set-frame-configuration configuration
+@defun set-frame-configuration configuration &optional nodelete
This function restores the state of frames described in
@var{configuration}.
+
+Ordinarily, this function deletes all existing frames not listed in
+@var{configuration}. But if @var{nodelete} is non-@code{nil}, the
+unwanted frames are iconified instead.
@end defun
@node Mouse Tracking
the top left corner of the inside of @var{frame}.
@end defun
+@defvar mouse-position-function
+If non-@code{nil}, the value of this variable is a function for
+@code{mouse-position} to call. @code{mouse-position} calls this
+function just before returning, with its normal return value as the
+sole argument, and it returns whatever this function returns to it.
+
+This abnormal hook exists for the benefit of packages like
+@file{xt-mouse.el} that need to do mouse handling at the Lisp level.
+@end defvar
+
@defun set-mouse-position frame x y
This function @dfn{warps the mouse} to position @var{x}, @var{y} in
frame @var{frame}. The arguments @var{x} and @var{y} are integers,
@node Window System Selections
@section Window System Selections
-@cindex selection (for X windows)
+@cindex selection (for window systems)
The X server records a set of @dfn{selections} which permit transfer of
data between application programs. The various selections are
This function returns the contents of cut buffer number @var{n}.
@end defun
-@defun x-set-cut-buffer string
+@defun x-set-cut-buffer string &optional push
This function stores @var{string} into the first cut buffer (cut buffer
-0), moving the other values down through the series of cut buffers, much
-like the way successive kills in Emacs move down the kill ring.
+0). If @var{push} is @code{nil}, only the first cut buffer is changed.
+If @var{push} is non-@code{nil}, that says to move the values down
+through the series of cut buffers, much like the way successive kills in
+Emacs move down the kill ring. In other words, the previous value of
+the first cut buffer moves into the second cut buffer, and the second to
+the third, and so on through all eight cut buffers.
@end defun
@defvar selection-coding-system
-@tindex selection-coding-system
This variable specifies the coding system to use when reading and
writing selections, the clipboard, or a cut buffer. @xref{Coding
-Systems}. The default is @code{compound-text}.
+Systems}. The default is @code{compound-text-with-extensions}, which
+converts to the text representation that X11 normally uses.
@end defvar
@cindex clipboard support (for MS-Windows)
When Emacs runs on MS-Windows, it does not implement X selections in
-general, but it it does support the clipboard. @code{x-get-selection}
+general, but it does support the clipboard. @code{x-get-selection}
and @code{x-set-selection} on MS-Windows support the text data type
only; if the clipboard holds other types of data, Emacs treats the
clipboard as empty.
@section Color Names
These functions provide a way to determine which color names are
-valid, and what they look like.
+valid, and what they look like. In some cases, the value depends on the
+@dfn{selected frame}, as described below; see @ref{Input Focus}, for the
+meaning of the term ``selected frame''.
@defun color-defined-p color &optional frame
@tindex color-defined-p
Note that this does not tell you whether the display you are using
really supports that color. When using X, you can ask for any defined
color on any kind of display, and you will get some result---typically,
-the best it knows how to do. Here's an approximate way to test whether
-your display supports the color @var{color}:
-
-@example
-(defun x-color-supported-p (color &optional frame)
- (and (color-defined-p color frame)
- (or (x-display-color-p frame)
- (member color '("black" "white"))
- (and (> (x-display-planes frame) 1)
- (equal color "gray")))))
-@end example
+the closest it can do. To determine whether a frame can really display
+a certain color, use @code{color-supported-p} (see below).
+@findex x-color-defined-p
This function used to be called @code{x-color-defined-p},
and that name is still supported as an alias.
@end defun
This function returns a list of the color names that are defined
and supported on frame @var{frame} (default, the selected frame).
+@findex x-defined-colors
This function used to be called @code{x-defined-colors},
and that name is still supported as an alias.
@end defun
+@defun color-supported-p color &optional frame background-p
+@tindex color-supported-p
+This returns @code{t} if @var{frame} can really display the color
+@var{color} (or at least something close to it). If @var{frame} is
+omitted or @code{nil}, the question applies to the selected frame.
+
+Some terminals support a different set of colors for foreground and
+background. If @var{background-p} is non-@code{nil}, that means you are
+asking whether @var{color} can be used as a background; otherwise you
+are asking whether it can be used as a foreground.
+
+The argument @var{color} must be a valid color name.
+@end defun
+
+@defun color-gray-p color &optional frame
+@tindex color-gray-p
+This returns @code{t} if @var{color} is a shade of gray, as defined on
+@var{frame}'s display. If @var{frame} is omitted or @code{nil}, the
+question applies to the selected frame. The argument @var{color} must
+be a valid color name.
+@end defun
+
@defun color-values color &optional frame
@tindex color-values
This function returns a value that describes what @var{color} should
is omitted or @code{nil}, the information is returned for the selected
frame's display.
+@findex x-color-values
This function used to be called @code{x-color-values},
and that name is still supported as an alias.
@end defun
@cindex colors on text-only terminals
Emacs can display color on text-only terminals, starting with version
-21. These terminals support only a small number of colors, and the
-computer uses small integers to select colors on the terminal. This
+21. These terminals usually support only a small number of colors, and
+the computer uses small integers to select colors on the terminal. This
means that the computer cannot reliably tell what the selected color
looks like; instead, you have to inform your application which small
integers correspond to which colors. However, Emacs does know the
standard set of colors and will try to use them automatically.
+ The functions described in this section control how terminal colors
+are used by Emacs.
+
@cindex rgb value
Several of these functions use or return @dfn{rgb values}. An rgb
value is a list of three integers, which give the amount of red, the
principle from 0 to 65535, but in practice the largest value used is
65280.
-@defun tty-define-color name number &optional rgb
-@tindex tty-define-color
+ These functions accept a display (either a frame or the name of a
+terminal) as an optional argument. We hope in the future to make Emacs
+support more than one text-only terminal at one time; then this argument
+will specify which terminal to operate on (the default being the
+selected frame's terminal; @pxref{Input Focus}). At present, though,
+the @var{display} argument has no effect.
+
+@defun tty-color-define name number &optional rgb display
+@tindex tty-color-define
This function associates the color name @var{name} with
color number @var{number} on the terminal.
like.
@end defun
-@defun tty-clear-colors
-@tindex tty-clear-colors
+@defun tty-color-clear &optional display
+@tindex tty-color-clear
This function clears the table of defined colors for a text-only terminal.
@end defun
-@defvar tty-color-alist
+@defun tty-color-alist &optional display
@tindex tty-color-alist
-This variable holds an alist recording the colors supported by the
-terminal.
+This function returns an alist recording the known colors supported by a
+text-only terminal.
Each element has the form @code{(@var{name} @var{number} . @var{rgb})}
or @code{(@var{name} @var{number})}. Here, @var{name} is the color
actually looks like.
@end defun
-@defun tty-color-approximate rgb
+@defun tty-color-approximate rgb &optional display
@tindex tty-color-approximate
-This function finds the closest available color, among those in
-@code{tty-color-alist}, to that described by the rgb value @var{rgb}.
+This function finds the closest color, among the known colors supported
+for @var{display}, to that described by the rgb value @var{rgb}.
@end defun
-@defun tty-color-translate color
+@defun tty-color-translate color &optional display
@tindex tty-color-translate
-This function finds the closest available color, among those in
-@code{tty-color-alist}, to the name @var{color}. If that name
-is not defined, the value is @code{nil}.
+This function finds the closest color to @var{color} among the known
+colors supported for @var{display}. If the name @var{color} is not
+defined, the value is @code{nil}.
-@var{color} can be an X-style @code{#@var{xxxyyyzzz}} specification
-instead of an actual name.
+@var{color} can be an X-style @code{"#@var{xxxyyyzzz}"} specification
+instead of an actual name. The format
+@code{"RGB:@var{xx}/@var{yy}/@var{zz}"} is also supported.
@end defun
@node Resources
variable to some other string, around a call to @code{x-get-resource}.
@end defvar
- @xref{Resources X,, X Resources, emacs, The GNU Emacs Manual}.
+ @xref{X Resources,, X Resources, emacs, The GNU Emacs Manual}.
-@node Server Data
-@section Data about the X Server
+@node Display Feature Testing
+@section Display Feature Testing
+@cindex display feature testing
- This section describes functions you can use to get information about
-the capabilities and origin of an X display that Emacs is using. Each
-of these functions lets you specify the display you are interested in:
-the @var{display} argument can be either a display name, or a frame
-(meaning use the display that frame is on). If you omit the
-@var{display} argument, or specify @code{nil}, that means to use the
-selected frame's display.
+ The functions in this section describe the basic capabilities of a
+particular display. Lisp programs can use them to adapt their behavior
+to what the display can do. For example, a program that ordinarly uses
+a popup menu could use the minibuffer if popup menus are not supported.
-@defun x-display-screens &optional display
-This function returns the number of screens associated with the display.
+ The optional argument @var{display} in these functions specifies which
+display to ask the question about. It can be a display name, a frame
+(which designates the display that frame is on), or @code{nil} (which
+refers to the selected frame's display, @pxref{Input Focus}).
+
+ @xref{Color Names}, @ref{Text Terminal Colors}, for other functions to
+obtain information about displays.
+
+@defun display-popup-menus-p &optional display
+@tindex display-popup-menus-p
+This function returns @code{t} if popup menus are supported on
+@var{display}, @code{nil} if not. Support for popup menus requires that
+the mouse be available, since the user cannot choose menu items without
+a mouse.
@end defun
-@defun x-server-version &optional display
-This function returns the list of version numbers of the X server
-running the display.
+@defun display-graphic-p &optional display
+@tindex display-graphic-p
+@cindex frames, more than one on display
+@cindex fonts, more than one on display
+This function returns @code{t} if @var{display} is a graphic display
+capable of displaying several frames and several different fonts at
+once. This is true for displays that use a window system such as X, and
+false for text-only terminals.
@end defun
-@defun x-server-vendor &optional display
-This function returns the vendor that provided the X server software.
+@defun display-mouse-p &optional display
+@tindex display-mouse-p
+@cindex mouse, availability
+This function returns @code{t} if @var{display} has a mouse available,
+@code{nil} if not.
+@end defun
+
+@defun display-color-p &optional display
+@tindex display-color-p
+@findex x-display-color-p
+This function returns @code{t} if the screen is a color screen.
+It used to be called @code{x-display-color-p}, and that name
+is still supported as an alias.
+@end defun
+
+@defun display-grayscale-p &optional display
+@tindex display-grayscale-p
+This function returns @code{t} if the screen can display shades of gray.
+(All color displays can do this.)
+@end defun
+
+@anchor{Display Face Attribute Testing}
+@defun display-supports-face-attributes-p attributes &optional display
+@tindex display-supports-face-attributes-p
+This function returns non-@code{nil} if all the face attributes in
+@var{attributes} are supported (@pxref{Face Attributes}).
+
+The definition of `supported' is somewhat heuristic, but basically
+means that a face containing all the attributes in @var{attributes},
+when merged with the default face for display, can be represented in a
+way that's
+
+@enumerate
+@item
+different in appearance than the default face, and
+
+@item
+`close in spirit' to what the attributes specify, if not exact.
+@end enumerate
+
+Point (2) implies that a @code{:weight black} attribute will be
+satisfied by any display that can display bold, as will
+@code{:foreground "yellow"} as long as some yellowish color can be
+displayed, but @code{:slant italic} will @emph{not} be satisfied by
+the tty display code's automatic substitution of a `dim' face for
+italic.
+@end defun
+
+@defun display-selections-p &optional display
+@tindex display-selections-p
+This function returns @code{t} if @var{display} supports selections.
+Windowed displays normally support selections, but they may also be
+supported in some other cases.
+@end defun
+
+@defun display-images-p &optional display
+This function returns @code{t} if @var{display} can display images.
+Windowed displays ought in principle to handle images, but some
+systems lack the support for that. On a display that does not support
+images, Emacs cannot display a tool bar.
@end defun
-@defun x-display-pixel-height &optional display
+@defun display-screens &optional display
+@tindex display-screens
+This function returns the number of screens associated with the display.
+@end defun
+
+@defun display-pixel-height &optional display
+@tindex display-pixel-height
This function returns the height of the screen in pixels.
@end defun
-@defun x-display-mm-height &optional display
-This function returns the height of the screen in millimeters.
+@defun display-mm-height &optional display
+@tindex display-mm-height
+This function returns the height of the screen in millimeters,
+or @code{nil} if Emacs cannot get that information.
@end defun
-@defun x-display-pixel-width &optional display
+@defun display-pixel-width &optional display
+@tindex display-pixel-width
This function returns the width of the screen in pixels.
@end defun
-@defun x-display-mm-width &optional display
-This function returns the width of the screen in millimeters.
+@defun display-mm-width &optional display
+@tindex display-mm-width
+This function returns the width of the screen in millimeters,
+or @code{nil} if Emacs cannot get that information.
@end defun
-@defun x-display-backing-store &optional display
-This function returns the backing store capability of the screen.
+@defun display-backing-store &optional display
+@tindex display-backing-store
+This function returns the backing store capability of the display.
+Backing store means recording the pixels of windows (and parts of
+windows) that are not exposed, so that when exposed they can be
+displayed very quickly.
+
Values can be the symbols @code{always}, @code{when-mapped}, or
-@code{not-useful}.
+@code{not-useful}. The function can also return @code{nil}
+when the question is inapplicable to a certain kind of display.
@end defun
-@defun x-display-save-under &optional display
+@defun display-save-under &optional display
+@tindex display-save-under
This function returns non-@code{nil} if the display supports the
-SaveUnder feature.
+SaveUnder feature. That feature is used by pop-up windows
+to save the pixels they obscure, so that they can pop down
+quickly.
@end defun
-@defun x-display-planes &optional display
+@defun display-planes &optional display
+@tindex display-planes
This function returns the number of planes the display supports.
+This is typically the number of bits per pixel.
+For a tty display, it is log to base two of the number of colours supported.
@end defun
-@defun x-display-visual-class &optional display
+@defun display-visual-class &optional display
+@tindex display-visual-class
This function returns the visual class for the screen. The value is one
of the symbols @code{static-gray}, @code{gray-scale},
@code{static-color}, @code{pseudo-color}, @code{true-color}, and
@code{direct-color}.
@end defun
-@defun x-display-grayscale-p &optional display
-This function returns @code{t} if the screen can display shades of gray.
+@defun display-color-cells &optional display
+@tindex display-color-cells
+This function returns the number of color cells the screen supports.
@end defun
-@defun x-display-color-p &optional display
-This function returns @code{t} if the screen is a color screen.
+ These functions obtain additional information specifically
+about X displays.
+
+@defun x-server-version &optional display
+This function returns the list of version numbers of the X server
+running the display.
@end defun
-@defun x-display-color-cells &optional display
-This function returns the number of color cells the screen supports.
+@defun x-server-vendor &optional display
+This function returns the vendor that provided the X server software.
@end defun
@ignore