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authorRichard M. Stallman <rms@gnu.org>2000-01-26 23:57:05 +0000
committerRichard M. Stallman <rms@gnu.org>2000-01-26 23:57:05 +0000
commita065c889e162c656778f469854d3c5c4de1ba61b (patch)
tree56f223f95e96fd6bfbfab7069bf55948058468c2 /lispref/frames.texi
parent6c67ddee2141633b7cc1e98bfa37da94313e5a8f (diff)
downloademacs-a065c889e162c656778f469854d3c5c4de1ba61b.tar.gz
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diff --git a/lispref/frames.texi b/lispref/frames.texi
index 6552ac7f332..a54bccf37e0 100644
--- a/lispref/frames.texi
+++ b/lispref/frames.texi
@@ -67,7 +67,7 @@ The frame is displayed on an MS-DOS terminal.
* 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
@@ -1587,16 +1587,50 @@ variable to some other string, around a call to @code{x-get-resource}.
@xref{Resources X,, 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.
+
+ 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).
+
+ @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 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 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
+
+ These functions obtain additional information specifically
+about X displays.
@defun x-display-screens &optional display
This function returns the number of screens associated with the display.