@c -*-texinfo-*- @c This is part of the GNU Emacs Lisp Reference Manual. @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2002, 2003, @c 2004, 2005, 2006 Free Software Foundation, Inc. @c See the file elisp.texi for copying conditions. @setfilename ../info/frames @node Frames, Positions, Windows, Top @chapter Frames @cindex frame In Emacs editing, A @dfn{frame} is a screen object that contains one or more Emacs windows. It's the kind of object that is called a ``window'' in the terminology of graphical environments; but we can't call it a ``window'' here, because Emacs uses that word in a different way. A frame initially contains a single main window and/or a minibuffer window; you can subdivide the main window vertically or horizontally into smaller windows. In Emacs Lisp, a @dfn{frame object} is a Lisp object that represents a frame on the screen. @cindex terminal frame When Emacs runs on a text-only terminal, it starts with one @dfn{terminal frame}. If you create additional ones, Emacs displays one and only one at any given time---on the terminal screen, of course. @cindex window frame When Emacs communicates directly with a supported window system, such 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. @defun framep object This predicate returns a non-@code{nil} value if @var{object} is a frame, and @code{nil} otherwise. For a frame, the value indicates which kind of display the frame uses: @table @code @item x The frame is displayed in an X window. @item t A terminal frame on a character display. @item mac The frame is displayed on a Macintosh. @item w32 The frame is displayed on MS-Windows 9X/NT. @item pc The frame is displayed on an MS-DOS terminal. @end table @end defun @menu * Creating Frames:: Creating additional frames. * Multiple Displays:: Creating frames on other displays. * Frame Parameters:: Controlling frame size, position, font, etc. * Frame Titles:: Automatic updating of frame titles. * Deleting Frames:: Frames last until explicitly deleted. * Finding All Frames:: How to examine all existing frames. * Frames and Windows:: A frame contains windows; display of text always works through windows. * Minibuffers and Frames:: How a frame finds the minibuffer to use. * Input Focus:: Specifying the selected frame. * Visibility of Frames:: Frames may be visible or invisible, or icons. * Raising and Lowering:: Raising a frame makes it hide other windows; lowering it makes the others hide it. * Frame Configurations:: Saving the state of all frames. * Mouse Tracking:: Getting events that say when the mouse moves. * Mouse Position:: Asking where the mouse is, or moving it. * Pop-Up Menus:: Displaying a menu for the user to select from. * Dialog Boxes:: Displaying a box to ask yes or no. * Pointer Shape:: Specifying the shape of the mouse pointer. * Window System Selections:: Transferring text to and from other X clients. * Drag and Drop:: Internals of Drag-and-Drop implementation. * Color Names:: Getting the definitions of color names. * Text Terminal Colors:: Defining colors for text-only terminals. * Resources:: Getting resource values from the server. * Display Feature Testing:: Determining the features of a terminal. @end menu @xref{Display}, for information about the related topic of controlling Emacs redisplay. @node Creating Frames @section Creating Frames To create a new frame, call the function @code{make-frame}. @defun make-frame &optional alist This function creates and returns a new frame, displaying the current buffer. If you are using a supported window system, it makes a window frame; otherwise, it makes a terminal frame. The argument is an alist specifying frame parameters. Any parameters not mentioned in @var{alist} default according to the value of the variable @code{default-frame-alist}; parameters not specified even there default from the standard X resources or whatever is used instead on your system. The set of possible parameters depends in principle on what kind of window system Emacs uses to display its frames. @xref{Window Frame Parameters}, for documentation of individual parameters you can specify. This function itself does not make the new frame the selected frame. @xref{Input Focus}. The previously selected frame remains selected. However, the window system may select the new frame for its own reasons, for instance if the frame appears under the mouse pointer and your setup is for focus to follow the pointer. @end defun @defvar 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 An abnormal hook run by @code{make-frame} after it creates the frame. Each function in @code{after-make-frame-functions} receives one argument, the frame just created. @end defvar @node Multiple Displays @section Multiple Displays @cindex multiple X displays @cindex displays, multiple A single Emacs can talk to more than one X display. Initially, Emacs uses just one display---the one chosen with the @code{DISPLAY} environment variable or with the @samp{--display} option (@pxref{Initial Options,,, emacs, The GNU Emacs Manual}). To connect to another display, use the command @code{make-frame-on-display} or specify 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. 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 is the one for the terminal that the currently selected frame belongs to. These variables include @code{default-minibuffer-frame}, @code{defining-kbd-macro}, @code{last-kbd-macro}, and @code{system-key-alist}. They are always terminal-local, and can never be buffer-local (@pxref{Buffer-Local Variables}) or frame-local. A single X server can handle more than one screen. A display name @samp{@var{host}:@var{server}.@var{screen}} has three parts; the last part specifies the screen number for a given server. When you use two screens belonging to one server, Emacs knows by the similarity in their names that they share a single keyboard, and it treats them as a single terminal. @deffn Command make-frame-on-display display &optional parameters This creates and returns a new frame on display @var{display}, taking the other frame parameters from @var{parameters}. Aside from the @var{display} argument, it is like @code{make-frame} (@pxref{Creating Frames}). @end deffn @defun x-display-list This returns a list that indicates which X displays Emacs has a connection to. The elements of the list are strings, and each one is a display name. @end defun @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. The optional argument @var{xrm-string}, if not @code{nil}, is a string of resource names and values, in the same format used in the @file{.Xresources} file. The values you specify override the resource values recorded in the X server itself; they apply to all Emacs frames created on this display. Here's an example of what this string might look like: @example "*BorderWidth: 3\n*InternalBorder: 2\n" @end example @xref{X Resources,, X Resources, emacs, The GNU Emacs Manual}. 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 This function closes the connection to display @var{display}. Before you can do this, you must first delete all the frames that were open on that display (@pxref{Deleting Frames}). @end defun @node Frame Parameters @section Frame Parameters A frame has many parameters that control its appearance and behavior. Just what parameters a frame has depends on what display mechanism it uses. Frame parameters exist mostly for the sake of window systems. A terminal frame has a few parameters, mostly for compatibility's sake; only the @code{height}, @code{width}, @code{name}, @code{title}, @code{menu-bar-lines}, @code{buffer-list} and @code{buffer-predicate} parameters do something special. If the terminal supports colors, the parameters @code{foreground-color}, @code{background-color}, @code{background-mode} and @code{display-type} are also meaningful. @menu * Parameter Access:: How to change a frame's parameters. * Initial Parameters:: Specifying frame parameters when you make a frame. * Window Frame Parameters:: List of frame parameters for window systems. * Size and Position:: Changing the size and position of a frame. * Geometry:: Parsing geometry specifications. @end menu @node Parameter Access @subsection Access to Frame Parameters These functions let you read and change the parameter values of a frame. @defun frame-parameter frame parameter This function returns the value of the parameter @var{parameter} (a symbol) of @var{frame}. If @var{frame} is @code{nil}, it returns the selected frame's parameter. If @var{frame} has no setting for @var{parameter}, this function returns @code{nil}. @end defun @defun frame-parameters &optional frame The function @code{frame-parameters} returns an alist listing all the parameters of @var{frame} and their values. If @var{frame} is @code{nil} or omitted, this returns the selected frame's parameters @end defun @defun modify-frame-parameters frame alist This function alters the parameters of frame @var{frame} based on the elements of @var{alist}. Each element of @var{alist} has the form @code{(@var{parm} . @var{value})}, where @var{parm} is a symbol naming a parameter. If you don't mention a parameter in @var{alist}, its value doesn't change. If @var{frame} is @code{nil}, it defaults to the selected frame. @end defun @defun modify-all-frames-parameters alist This function alters the frame parameters of all existing frames according to @var{alist}, then modifies @code{default-frame-alist} (and, if necessary, @code{initial-frame-alist}) to apply the same parameter values to frames that will be created henceforth. @end defun @node Initial Parameters @subsection Initial Frame Parameters You can specify the parameters for the initial startup frame by setting @code{initial-frame-alist} in your init file (@pxref{Init File}). @defvar initial-frame-alist This variable's value is an alist of parameter values used when creating the initial window frame. You can set this variable to specify the appearance of the initial frame without altering subsequent frames. Each element has the form: @example (@var{parameter} . @var{value}) @end example Emacs creates the initial frame before it reads your init file. After reading that file, Emacs checks @code{initial-frame-alist}, and applies the parameter settings in the altered value to the already created initial frame. If these settings affect the frame geometry and appearance, you'll see 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{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 you don't want them to apply to subsequent frames, here's how to achieve this. Specify parameters in @code{default-frame-alist} to override the X resources for subsequent frames; then, to prevent these from affecting the initial frame, specify the same parameters in @code{initial-frame-alist} with values that match the X resources. @end defvar If these parameters specify a separate minibuffer-only frame with @code{(minibuffer . nil)}, and you have not created one, Emacs creates one for you. @defvar minibuffer-frame-alist This variable's value is an alist of parameter values used when creating an initial minibuffer-only frame---if such a frame is needed, according to the parameters for the main initial frame. @end defvar @defvar default-frame-alist This is an alist specifying default values of frame parameters for all Emacs frames---the first frame, and subsequent frames. When using the X Window System, you can get the same results by means of X resources in many cases. Setting this variable does not affect existing frames. @end defvar See also @code{special-display-frame-alist}. @xref{Definition of special-display-frame-alist}. If you use options that specify window appearance when you invoke Emacs, they take effect by adding elements to @code{default-frame-alist}. One exception is @samp{-geometry}, which adds the specified position to @code{initial-frame-alist} instead. @xref{Emacs Invocation,, Command Line Arguments for Emacs Invocation, emacs, The GNU Emacs Manual}. @node Window Frame Parameters @subsection Window Frame Parameters Just what parameters a frame has depends on what display mechanism it uses. This section describes the parameters that have special meanings on some or all kinds of terminals. Of these, @code{name}, @code{title}, @code{height}, @code{width}, @code{buffer-list} and @code{buffer-predicate} provide meaningful information in terminal frames, and @code{tty-color-mode} is meaningful @emph{only} in terminal frames. @menu * Basic Parameters:: Parameters that are fundamental. * Position Parameters:: The position of the frame on the screen. * Size Parameters:: Frame's size. * Layout Parameters:: Size of parts of the frame, and enabling or disabling some parts. * Buffer Parameters:: Which buffers have been or should be shown. * Management Parameters:: Communicating with the window manager. * Cursor Parameters:: Controlling the cursor appearance. * Color Parameters:: Colors of various parts of the frame. @end menu @node Basic Parameters @subsubsection Basic Parameters These frame parameters give the most basic information about the frame. @code{title} and @code{name} are meaningful on all terminals. @table @code @item display The display on which to open this frame. It should be a string of the form @code{"@var{host}:@var{dpy}.@var{screen}"}, just like the @code{DISPLAY} environment variable. @item display-type This parameter describes the range of possible colors that can be used in this frame. Its value is @code{color}, @code{grayscale} or @code{mono}. @item title If a frame has a non-@code{nil} title, it appears in the window system's border for the frame, and also in the mode line of windows in that frame if @code{mode-line-frame-identification} uses @samp{%F} (@pxref{%-Constructs}). This is normally the case when Emacs is not using a window system, and can only display one frame at a time. @xref{Frame Titles}. @item name The name of the frame. The frame name serves as a default for the frame title, if the @code{title} parameter is unspecified or @code{nil}. If you don't specify a name, Emacs sets the frame name automatically (@pxref{Frame Titles}). If you specify the frame name explicitly when you create the frame, the name is also used (instead of the name of the Emacs executable) when looking up X resources for the frame. @end table @node Position Parameters @subsubsection Position Parameters Position parameters' values are normally measured in pixels, but on text-only terminals they count characters or lines instead. @table @code @item left The screen position of the left edge, in pixels, with respect to the left edge of the screen. The value may be a positive number @var{pos}, or a list of the form @code{(+ @var{pos})} which permits specifying a negative @var{pos} value. A negative number @minus{}@var{pos}, or a list of the form @code{(- @var{pos})}, actually specifies the position of the right edge of the window with respect to the right edge of the screen. A positive value of @var{pos} counts toward the left. @strong{Reminder:} if the parameter is a negative integer @minus{}@var{pos}, then @var{pos} is positive. Some window managers ignore program-specified positions. If you want to be sure the position you specify is not ignored, specify a non-@code{nil} value for the @code{user-position} parameter as well. @item top The screen position of the top edge, in pixels, with respect to the top edge of the screen. It works just like @code{left}, except vertically instead of horizontally. @item icon-left The screen position of the left edge @emph{of the frame's icon}, in pixels, counting from the left edge of the screen. This takes effect if and when the frame is iconified. If you specify a value for this parameter, then you must also specify a value for @code{icon-top} and vice versa. The window manager may ignore these two parameters. @item icon-top The screen position of the top edge @emph{of the frame's icon}, in pixels, counting from the top edge of the screen. This takes effect if and when the frame is iconified. @item user-position When you create a frame and specify its screen position with the @code{left} and @code{top} parameters, use this parameter to say whether the specified position was user-specified (explicitly requested in some way by a human user) or merely program-specified (chosen by a program). A non-@code{nil} value says the position was user-specified. Window managers generally heed user-specified positions, and some heed program-specified positions too. But many ignore program-specified positions, placing the window in a default fashion or letting the user place it with the mouse. Some window managers, including @code{twm}, let the user specify whether to obey program-specified positions or ignore them. When you call @code{make-frame}, you should specify a non-@code{nil} value for this parameter if the values of the @code{left} and @code{top} parameters represent the user's stated preference; otherwise, use @code{nil}. @end table @node Size Parameters @subsubsection Size Parameters Size parameters' values are normally measured in pixels, but on text-only terminals they count characters or lines instead. @table @code @item height The height of the frame contents, in characters. (To get the height in pixels, call @code{frame-pixel-height}; see @ref{Size and Position}.) @item width 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 user-size This does for the size parameters @code{height} and @code{width} what the @code{user-position} parameter (see above) does for the position parameters @code{top} and @code{left}. @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. @end table @node Layout Parameters @subsubsection Layout Parameters These frame parameters enable or disable various parts of the frame, or control their sizes. @table @code @item border-width The width in pixels of the frame's border. @item internal-border-width The distance in pixels between text (or fringe) and the frame's border. @item vertical-scroll-bars Whether the frame has scroll bars for vertical scrolling, and which side of the frame they should be on. The possible values are @code{left}, @code{right}, and @code{nil} for no scroll bars. @ignore @item horizontal-scroll-bars Whether the frame has scroll bars for horizontal scrolling (non-@code{nil} means yes). Horizontal scroll bars are not currently implemented. @end ignore @item scroll-bar-width The width of vertical scroll bars, in pixels, or @code{nil} meaning to use the default width. @item left-fringe @itemx right-fringe The default width of the left and right fringes of windows in this frame (@pxref{Fringes}). If either of these is zero, that effectively removes the corresponding fringe. A value of @code{nil} stands for the standard fringe width, which is the width needed to display the fringe bitmaps. The combined fringe widths must add up to an integral number of columns, so the actual default fringe widths for the frame may be larger than the specified values. The extra width needed to reach an acceptable total is distributed evenly between the left and right fringe. However, you can force one fringe or the other to a precise width by specifying that width as a negative integer. If both widths are negative, only the left fringe gets the specified width. @item menu-bar-lines The number of lines to allocate at the top of the frame for a menu bar. The default is 1. A value of @code{nil} means don't display a menu bar. @xref{Menu Bar}. (The X toolkit and GTK allow at most one menu bar line; they treat larger values as 1.) @item tool-bar-lines The number of lines to use for the tool bar. A value of @code{nil} means don't display a tool bar. (GTK allows at most one tool bar line; it treats larger values as 1.) @item line-spacing Additional space to leave below each text line, in pixels (a positive integer). @xref{Line Height}, for more information. @end table @node Buffer Parameters @subsubsection Buffer Parameters These frame parameters, meaningful on all kinds of terminals, deal with which buffers have been, or should, be displayed in the frame. @table @code @item minibuffer Whether this frame has its own minibuffer. The value @code{t} means yes, @code{nil} means no, @code{only} means this frame is just a minibuffer. If the value is a minibuffer window (in some other frame), the new frame uses that minibuffer. @item buffer-predicate The buffer-predicate function for this frame. The function @code{other-buffer} uses this predicate (from the selected frame) to decide which buffers it should consider, if the predicate is not @code{nil}. It calls the predicate with one argument, a buffer, once for each buffer; if the predicate returns a non-@code{nil} value, it considers that buffer. @item buffer-list A list of buffers that have been selected in this frame, ordered most-recently-selected first. @item unsplittable If non-@code{nil}, this frame's window is never split automatically. @end table @node Management Parameters @subsubsection Window Management Parameters These frame parameters, meaningful only on window system displays, interact with the window manager. @table @code @item visibility The state of visibility of the frame. There are three possibilities: @code{nil} for invisible, @code{t} for visible, and @code{icon} for iconified. @xref{Visibility of Frames}. @item auto-raise Whether selecting the frame raises it (non-@code{nil} means yes). @item auto-lower Whether deselecting the frame lowers it (non-@code{nil} means yes). @item icon-type The type of icon to use for this frame when it is iconified. If the value is a string, that specifies a file containing a bitmap to use. Any other non-@code{nil} value specifies the default bitmap icon (a picture of a gnu); @code{nil} specifies a text icon. @item icon-name The name to use in the icon for this frame, when and if the icon appears. If this is @code{nil}, the frame's title is used. @item window-id The number of the window-system window used by the frame to contain the actual Emacs windows. @item outer-window-id The number of the outermost window-system window used for the whole frame. @item wait-for-wm If non-@code{nil}, tell Xt to wait for the window manager to confirm geometry changes. Some window managers, including versions of Fvwm2 and KDE, fail to confirm, so Xt hangs. Set this to @code{nil} to prevent hanging with those window managers. @ignore @item parent-id @c ??? Not yet working. The X window number of the window that should be the parent of this one. Specifying this lets you create an Emacs window inside some other application's window. (It is not certain this will be implemented; try it and see if it works.) @end ignore @end table @node Cursor Parameters @subsubsection Cursor Parameters This frame parameter controls the way the cursor looks. @table @code @item cursor-type How to display the cursor. Legitimate values are: @table @code @item box Display a filled box. (This is the default.) @item hollow Display a hollow box. @item nil Don't display a cursor. @item bar Display a vertical bar between characters. @item (bar . @var{width}) Display a vertical bar @var{width} pixels wide between characters. @item hbar Display a horizontal bar. @item (hbar . @var{height}) Display a horizontal bar @var{height} pixels high. @end table @end table @vindex cursor-type The buffer-local variable @code{cursor-type} overrides the value of the @code{cursor-type} frame parameter, but if it is @code{t}, that means to use the cursor specified for the frame. @defvar blink-cursor-alist This variable specifies how to blink the cursor. Each element has the form @code{(@var{on-state} . @var{off-state})}. Whenever the cursor type equals @var{on-state} (comparing using @code{equal}), the corresponding @var{off-state} specifies what the cursor looks like when it blinks ``off''. Both @var{on-state} and @var{off-state} should be suitable values for the @code{cursor-type} frame parameter. There are various defaults for how to blink each type of cursor, if the type is not mentioned as an @var{on-state} here. Changes in this variable do not take effect immediately, because the variable is examined only when you specify the @code{cursor-type} parameter. @end defvar @node Color Parameters @subsubsection Color Parameters These frame parameters control the use of colors. @table @code @item background-mode This parameter is either @code{dark} or @code{light}, according to whether the background color is a light one or a dark one. @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)} specifies use of the ANSI escape sequences for 8 standard text colors. A value of -1 turns off color support. If the parameter's value is a symbol, it specifies a number through the value of @code{tty-color-mode-alist}, and the associated number is used instead. @item screen-gamma @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 the 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. @end table These frame parameters are semi-obsolete in that they are automatically equivalent to particular face attributes of particular faces. @table @code @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}). It is equivalent to the @code{font} attribute of the @code{default} face. @item foreground-color The color to use for the image of a character. It is equivalent to the @code{:foreground} attribute of the @code{default} face. @item background-color The color to use for the background of characters. It is equivalent to the @code{:background} attribute of the @code{default} face. @item mouse-color The color for the mouse pointer. It is equivalent to the @code{:background} attribute of the @code{mouse} face. @item cursor-color The color for the cursor that shows point. It is equivalent to the @code{:background} attribute of the @code{cursor} face. @item border-color The color for the border of the frame. It is equivalent to the @code{:background} attribute of the @code{border} face. @item scroll-bar-foreground If non-@code{nil}, the color for the foreground of scroll bars. It is equivalent to the @code{:foreground} attribute of the @code{scroll-bar} face. @item scroll-bar-background If non-@code{nil}, the color for the background of scroll bars. It is equivalent to the @code{:background} attribute of the @code{scroll-bar} face. @end table @node Size and Position @subsection Frame Size And Position @cindex size of frame @cindex screen size @cindex frame size @cindex resize frame You can read or change the size and position of a frame using the frame parameters @code{left}, @code{top}, @code{height}, and @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. (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 @var{left} and @var{top}. These arguments are measured in pixels, and normally count from the top left corner of the screen. Negative parameter values position the bottom edge of the window up from the bottom edge of the screen, or the right window edge to the left of the right edge of the screen. It would probably be better if the values were always counted from the left and top, so that negative arguments would position the frame partly off the top or left edge of the screen, but it seems inadvisable to change that now. @end defun @defun frame-height &optional frame @defunx frame-width &optional frame These functions return the height and width of @var{frame}, measured in lines and columns. If you don't supply @var{frame}, they use the selected frame. @end defun @defun screen-height @defunx screen-width These functions are old aliases for @code{frame-height} and @code{frame-width}. When you are using a non-window terminal, the size of the frame is normally the same as the size of the terminal screen. @end defun @defun frame-pixel-height &optional frame @defunx frame-pixel-width &optional frame These functions return the height and width of @var{frame}, measured in pixels. If you don't supply @var{frame}, they use the selected frame. @end defun @defun frame-char-height &optional frame @defunx frame-char-width &optional frame These functions return the height and width of a character in @var{frame}, measured in pixels. The values depend on the choice of font. If you don't supply @var{frame}, these functions use the selected frame. @end defun @defun set-frame-size frame cols rows This function sets the size of @var{frame}, measured in characters; @var{cols} and @var{rows} specify the new width and height. To set the size based on values measured in pixels, use @code{frame-char-height} and @code{frame-char-width} to convert them to units of characters. @end defun @defun set-frame-height frame lines &optional pretend This function resizes @var{frame} to a height of @var{lines} lines. The sizes of existing windows in @var{frame} are altered proportionally to fit. If @var{pretend} is non-@code{nil}, then Emacs displays @var{lines} lines of output in @var{frame}, but does not change its value for the actual height of the frame. This is only useful for a terminal frame. Using a smaller height than the terminal actually implements may be useful to reproduce behavior observed on a smaller screen, or if the terminal malfunctions when using its whole screen. Setting the frame height ``for real'' does not always work, because knowing the correct actual size may be necessary for correct cursor positioning on a terminal frame. @end defun @defun set-frame-width frame width &optional pretend This function sets the width of @var{frame}, measured in characters. The argument @var{pretend} has the same meaning as in @code{set-frame-height}. @end defun @findex set-screen-height @findex set-screen-width The older functions @code{set-screen-height} and @code{set-screen-width} were used to specify the height and width of the screen, in Emacs versions that did not support multiple frames. They are semi-obsolete, but still work; they apply to the selected frame. @node Geometry @subsection Geometry Here's how to examine the data in an X-style window geometry specification: @defun x-parse-geometry geom @cindex geometry specification The function @code{x-parse-geometry} converts a standard X window geometry string to an alist that you can use as part of the argument to @code{make-frame}. The alist describes which parameters were specified in @var{geom}, and gives the values specified for them. Each element looks like @code{(@var{parameter} . @var{value})}. The possible @var{parameter} values are @code{left}, @code{top}, @code{width}, and @code{height}. For the size parameters, the value must be an integer. The position parameter names @code{left} and @code{top} are not totally accurate, because some values indicate the position of the right or bottom edges instead. These are the @var{value} possibilities for the position parameters: @table @asis @item an integer A positive integer relates the left edge or top edge of the window to the left or top edge of the screen. A negative integer relates the right or bottom edge of the window to the right or bottom edge of the screen. @item @code{(+ @var{position})} This specifies the position of the left or top edge of the window relative to the left or top edge of the screen. The integer @var{position} may be positive or negative; a negative value specifies a position outside the screen. @item @code{(- @var{position})} This specifies the position of the right or bottom edge of the window relative to the right or bottom edge of the screen. The integer @var{position} may be positive or negative; a negative value specifies a position outside the screen. @end table Here is an example: @example (x-parse-geometry "35x70+0-0") @result{} ((height . 70) (width . 35) (top - 0) (left . 0)) @end example @end defun @node Frame Titles @section Frame Titles Every frame has a @code{name} parameter; this serves as the default for the frame title which window systems typically display at the top of the frame. You can specify a name explicitly by setting the @code{name} frame property. Normally you don't specify the name explicitly, and Emacs computes the frame name automatically based on a template stored in the variable @code{frame-title-format}. Emacs recomputes the name each time the frame is redisplayed. @defvar frame-title-format This variable specifies how to compute a name for a frame when you have not explicitly specified one. The variable's value is actually a mode line construct, just like @code{mode-line-format}. @xref{Mode Line Data}. @end defvar @defvar icon-title-format This variable specifies how to compute the name for an iconified frame, when you have not explicitly specified the frame title. This title appears in the icon itself. @end defvar @defvar multiple-frames This variable is set automatically by Emacs. Its value is @code{t} when there are two or more frames (not counting minibuffer-only frames or invisible frames). The default value of @code{frame-title-format} uses @code{multiple-frames} so as to put the buffer name in the frame title only when there is more than one frame. The value of this variable is not guaranteed to be accurate except while processing @code{frame-title-format} or @code{icon-title-format}. @end defvar @node Deleting Frames @section Deleting Frames @cindex deletion of frames Frames remain potentially visible until you explicitly @dfn{delete} them. A deleted frame cannot appear on the screen, but continues to exist as a Lisp object until there are no references to it. @deffn Command delete-frame &optional frame force @vindex delete-frame-functions This function deletes the frame @var{frame}. Unless @var{frame} is a tooltip, it first runs the hook @code{delete-frame-functions} (each function gets one argument, @var{frame}). 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 The function @code{frame-live-p} returns non-@code{nil} if the frame @var{frame} has not been deleted. The possible non-@code{nil} return values are like those of @code{framep}. @xref{Frames}. @end defun Some window managers provide a command to delete a window. These work by sending a special message to the program that operates the window. When Emacs gets one of these commands, it generates a @code{delete-frame} event, whose normal definition is a command that calls the function @code{delete-frame}. @xref{Misc Events}. @node Finding All Frames @section Finding All Frames @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, 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 This function returns a list of just the currently visible frames. @xref{Visibility of Frames}. (Terminal frames always count as ``visible'', even though only the selected one is actually displayed.) @end defun @defun next-frame &optional frame minibuf The function @code{next-frame} lets you cycle conveniently through all 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: @table @asis @item @code{nil} Exclude minibuffer-only frames. @item @code{visible} Consider all visible frames. @item 0 Consider all visible or iconified frames. @item a window Consider only the frames using that particular window as their minibuffer. @item anything else Consider all frames. @end table @end defun @defun previous-frame &optional frame minibuf Like @code{next-frame}, but cycles through all frames in the opposite direction. @end defun See also @code{next-window} and @code{previous-window}, in @ref{Cyclic Window Ordering}. @node Frames and Windows @section Frames and Windows Each window is part of one and only one frame; you can get the frame with @code{window-frame}. @defun window-frame window This function returns the frame that @var{window} is on. @end defun All the non-minibuffer windows in a frame are arranged in a cyclic order. The order runs from the frame's top window, which is at the upper left corner, down and to the right, until it reaches the window at the lower right corner (always the minibuffer window, if the frame has one), and then it moves back to the top. @xref{Cyclic Window Ordering}. @defun frame-first-window &optional frame This returns the topmost, leftmost window of frame @var{frame}. If omitted or @code{nil}, @var{frame} defaults to the selected frame. @end defun At any time, exactly one window on any frame is @dfn{selected within the frame}. The significance of this designation is that selecting the frame also selects this window. You can get the frame's current selected window with @code{frame-selected-window}. @defun frame-selected-window &optional frame This function returns the window on @var{frame} that is selected within @var{frame}. If omitted or @code{nil}, @var{frame} defaults to the selected frame. @end defun @defun set-frame-selected-window frame window This sets the selected window of frame @var{frame} to @var{window}. If @var{frame} is @code{nil}, it operates on the selected frame. If @var{frame} is the selected frame, this makes @var{window} the selected window. This function returns @var{window}. @end defun Conversely, selecting a window for Emacs with @code{select-window} also makes that window selected within its frame. @xref{Selecting Windows}. Another function that (usually) returns one of the windows in a given frame is @code{minibuffer-window}. @xref{Definition of minibuffer-window}. @node Minibuffers and Frames @section Minibuffers and Frames Normally, each frame has its own minibuffer window at the bottom, which is used whenever that frame is selected. If the frame has a minibuffer, you can get it with @code{minibuffer-window} (@pxref{Definition of minibuffer-window}). However, you can also create a frame with no minibuffer. Such a frame must use the minibuffer window of some other frame. When you create the frame, you can specify explicitly the minibuffer window to use (in some other frame). If you don't, then the minibuffer is found in the frame which is the value of the variable @code{default-minibuffer-frame}. Its value should be a frame that does have a minibuffer. If you use a minibuffer-only frame, you might want that frame to raise when you enter the minibuffer. If so, set the variable @code{minibuffer-auto-raise} to @code{t}. @xref{Raising and Lowering}. @defvar default-minibuffer-frame This variable specifies the frame to use for the minibuffer window, by default. It does not affect existing frames. It is always local to the current terminal and cannot be buffer-local. @xref{Multiple Displays}. @end defvar @node Input Focus @section Input Focus @cindex input focus @cindex selected frame 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 Some window systems and window managers direct keyboard input to the window object that the mouse is in; others require explicit clicks or commands to @dfn{shift the focus} to various window objects. Either way, Emacs automatically keeps track of which frame has the focus. To switch to a different frame from a Lisp function, call @code{select-frame-set-input-focus}. Lisp programs can also switch frames ``temporarily'' by calling the function @code{select-frame}. This does not alter the window system's concept of focus; rather, it escapes from the window manager's control until that control is somehow reasserted. When using a text-only terminal, only one frame can be displayed at a time on the terminal, so after a call to @code{select-frame}, the next redisplay actually displays the newly selected frame. This frame remains selected until a subsequent call to @code{select-frame} or @code{select-frame-set-input-focus}. Each terminal frame has a number which appears in the mode line before the buffer name (@pxref{Mode Line Variables}). @defun select-frame-set-input-focus frame This function makes @var{frame} the selected frame, raises it (should it happen to be obscured by other frames) and tries to give it the X server's focus. On a text-only terminal, the next redisplay displays the new frame on the entire terminal screen. The return value of this function is not significant. @end defun @c ??? This is not yet implemented properly. @defun select-frame frame 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. (If you are using a window system, the previously selected frame may be restored as the selected frame after return to the command loop, because it still may have the window system's input focus.) The specified @var{frame} becomes the selected frame, as explained above, and the terminal that @var{frame} is on becomes the selected terminal. This function returns @var{frame}, or @code{nil} if @var{frame} has been deleted. 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 the server and window manager request. It does so by generating a special kind of input event, called a @dfn{focus} event, when appropriate. The command loop handles a focus event by calling @code{handle-switch-frame}. @xref{Focus Events}. @deffn Command handle-switch-frame frame This function handles a focus event by selecting frame @var{frame}. Focus events normally do their job by invoking this command. Don't call it for any other reason. @end deffn @defun redirect-frame-focus frame &optional focus-frame This function redirects focus from @var{frame} to @var{focus-frame}. This means that @var{focus-frame} will receive subsequent keystrokes and events intended for @var{frame}. After such an event, the value of @code{last-event-frame} will be @var{focus-frame}. Also, switch-frame events specifying @var{frame} will instead select @var{focus-frame}. If @var{focus-frame} is omitted or @code{nil}, that cancels any existing redirection for @var{frame}, which therefore once again receives its own events. One use of focus redirection is for frames that don't have minibuffers. These frames use minibuffers on other frames. Activating a minibuffer on another frame redirects focus to that frame. This puts the focus on the minibuffer's frame, where it belongs, even though the mouse remains in the frame that activated the minibuffer. Selecting a frame can also change focus redirections. Selecting frame @code{bar}, when @code{foo} had been selected, changes any redirections pointing to @code{foo} so that they point to @code{bar} instead. This allows focus redirection to work properly when the user switches from one frame to another using @code{select-window}. This means that a frame whose focus is redirected to itself is treated differently from a frame whose focus is not redirected. @code{select-frame} affects the former but not the latter. The redirection lasts until @code{redirect-frame-focus} is called to change it. @end defun @defopt 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 position consistent with the new selected frame. @end defopt @node Visibility of Frames @section Visibility of Frames @cindex visible frame @cindex invisible frame @cindex iconified frame @cindex frame visibility A window frame may be @dfn{visible}, @dfn{invisible}, or @dfn{iconified}. If it is visible, you can see its contents. If it is iconified, the frame's contents do not appear on the screen, but an icon does. If the frame is invisible, it doesn't show on the screen, not even as an icon. Visibility is meaningless for terminal frames, since only the selected one is actually displayed in any case. @deffn Command make-frame-visible &optional frame This function makes frame @var{frame} visible. If you omit @var{frame}, it makes the selected frame visible. @end deffn @deffn Command make-frame-invisible &optional frame force This function makes frame @var{frame} invisible. If you omit @var{frame}, it makes the selected frame invisible. Unless @var{force} is non-@code{nil}, this function refuses to make @var{frame} invisible if all other frames are invisible.. @end deffn @deffn Command iconify-frame &optional frame This function iconifies frame @var{frame}. If you omit @var{frame}, it iconifies the selected frame. @end deffn @defun frame-visible-p frame This returns the visibility status of frame @var{frame}. The value is @code{t} if @var{frame} is visible, @code{nil} if it is invisible, and @code{icon} if it is iconified. On a text-only terminal, all frames are considered visible, whether they are currently being displayed or not, and this function returns @code{t} for all frames. @end defun The visibility status of a frame is also available as a frame parameter. You can read or change it as such. @xref{Management Parameters}. The user can iconify and deiconify frames with the window manager. This happens below the level at which Emacs can exert any control, but Emacs does provide events that you can use to keep track of such changes. @xref{Misc Events}. @node Raising and Lowering @section Raising and Lowering Frames Most window systems use a desktop metaphor. Part of this metaphor is the idea that windows are stacked in a notional third dimension perpendicular to the screen surface, and thus ordered from ``highest'' to ``lowest''. Where two windows overlap, the one higher up covers the one underneath. Even a window at the bottom of the stack can be seen if no other window overlaps it. @cindex raising a frame @cindex lowering a frame A window's place in this ordering is not fixed; in fact, users tend to change the order frequently. @dfn{Raising} a window means moving it ``up'', to the top of the stack. @dfn{Lowering} a window means moving it to the bottom of the stack. This motion is in the notional third dimension only, and does not change the position of the window on the screen. You can raise and lower Emacs frame Windows with these functions: @deffn Command raise-frame &optional frame This function raises frame @var{frame} (default, the selected frame). If @var{frame} is invisible or iconified, this makes it visible. @end deffn @deffn Command lower-frame &optional frame This function lowers frame @var{frame} (default, the selected frame). @end deffn @defopt minibuffer-auto-raise If this is non-@code{nil}, activation of the minibuffer raises the frame that the minibuffer window is in. @end defopt You can also enable auto-raise (raising automatically when a frame is selected) or auto-lower (lowering automatically when it is deselected) for any frame using frame parameters. @xref{Management Parameters}. @node Frame Configurations @section Frame Configurations @cindex frame configuration A @dfn{frame configuration} records the current arrangement of frames, all their properties, and the window configuration of each one. (@xref{Window Configurations}.) @defun current-frame-configuration This function returns a frame configuration list that describes the current arrangement of frames and their contents. @end defun @defun set-frame-configuration configuration &optional nodelete This function restores the state of frames described in @var{configuration}. However, this function does not restore deleted frames. 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 @section Mouse Tracking @cindex mouse tracking @cindex tracking the mouse Sometimes it is useful to @dfn{track} the mouse, which means to display something to indicate where the mouse is and move the indicator as the mouse moves. For efficient mouse tracking, you need a way to wait until the mouse actually moves. The convenient way to track the mouse is to ask for events to represent mouse motion. Then you can wait for motion by waiting for an event. In addition, you can easily handle any other sorts of events that may occur. That is useful, because normally you don't want to track the mouse forever---only until some other event, such as the release of a button. @defspec track-mouse body@dots{} This special form executes @var{body}, with generation of mouse motion events enabled. Typically @var{body} would use @code{read-event} to read the motion events and modify the display accordingly. @xref{Motion Events}, for the format of mouse motion events. The value of @code{track-mouse} is that of the last form in @var{body}. You should design @var{body} to return when it sees the up-event that indicates the release of the button, or whatever kind of event means it is time to stop tracking. @end defspec The usual purpose of tracking mouse motion is to indicate on the screen the consequences of pushing or releasing a button at the current position. In many cases, you can avoid the need to track the mouse by using the @code{mouse-face} text property (@pxref{Special Properties}). That works at a much lower level and runs more smoothly than Lisp-level mouse tracking. @ignore @c These are not implemented yet. These functions change the screen appearance instantaneously. The effect is transient, only until the next ordinary Emacs redisplay. That is OK for mouse tracking, since it doesn't make sense for mouse tracking to change the text, and the body of @code{track-mouse} normally reads the events itself and does not do redisplay. @defun x-contour-region window beg end This function draws lines to make a box around the text from @var{beg} to @var{end}, in window @var{window}. @end defun @defun x-uncontour-region window beg end This function erases the lines that would make a box around the text from @var{beg} to @var{end}, in window @var{window}. Use it to remove a contour that you previously made by calling @code{x-contour-region}. @end defun @defun x-draw-rectangle frame left top right bottom This function draws a hollow rectangle on frame @var{frame} with the specified edge coordinates, all measured in pixels from the inside top left corner. It uses the cursor color, the one used for indicating the location of point. @end defun @defun x-erase-rectangle frame left top right bottom This function erases a hollow rectangle on frame @var{frame} with the specified edge coordinates, all measured in pixels from the inside top left corner. Erasure means redrawing the text and background that normally belong in the specified rectangle. @end defun @end ignore @node Mouse Position @section Mouse Position @cindex mouse position @cindex position of mouse The functions @code{mouse-position} and @code{set-mouse-position} give access to the current position of the mouse. @defun mouse-position This function returns a description of the position of the mouse. The value looks like @code{(@var{frame} @var{x} . @var{y})}, where @var{x} and @var{y} are integers giving the position in characters relative to 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, giving the position in characters relative to the top left corner of the inside of @var{frame}. If @var{frame} is not visible, this function does nothing. The return value is not significant. @end defun @defun mouse-pixel-position This function is like @code{mouse-position} except that it returns coordinates in units of pixels rather than units of characters. @end defun @defun set-mouse-pixel-position frame x y This function warps the mouse like @code{set-mouse-position} except that @var{x} and @var{y} are in units of pixels rather than units of characters. These coordinates are not required to be within the frame. If @var{frame} is not visible, this function does nothing. The return value is not significant. @end defun @need 3000 @node Pop-Up Menus @section Pop-Up Menus When using a window system, a Lisp program can pop up a menu so that the user can choose an alternative with the mouse. @defun x-popup-menu position menu This function displays a pop-up menu and returns an indication of what selection the user makes. The argument @var{position} specifies where on the screen to put the top left corner of the menu. It can be either a mouse button event (which says to put the menu where the user actuated the button) or a list of this form: @example ((@var{xoffset} @var{yoffset}) @var{window}) @end example @noindent where @var{xoffset} and @var{yoffset} are coordinates, measured in pixels, counting from the top left corner of @var{window}. @var{window} may be a window or a frame. If @var{position} is @code{t}, it means to use the current mouse position. If @var{position} is @code{nil}, it means to precompute the key binding equivalents for the keymaps specified in @var{menu}, without actually displaying or popping up the menu. The argument @var{menu} says what to display in the menu. It can be a keymap or a list of keymaps (@pxref{Menu Keymaps}). In this case, the return value is the list of events corresponding to the user's choice. (This list has more than one element if the choice occurred in a submenu.) Note that @code{x-popup-menu} does not actually execute the command bound to that sequence of events. Alternatively, @var{menu} can have the following form: @example (@var{title} @var{pane1} @var{pane2}...) @end example @noindent where each pane is a list of form @example (@var{title} @var{item1} @var{item2}...) @end example Each item should normally be a cons cell @code{(@var{line} . @var{value})}, where @var{line} is a string, and @var{value} is the value to return if that @var{line} is chosen. An item can also be a string; this makes a non-selectable line in the menu. If the user gets rid of the menu without making a valid choice, for instance by clicking the mouse away from a valid choice or by typing keyboard input, then this normally results in a quit and @code{x-popup-menu} does not return. But if @var{position} is a mouse button event (indicating that the user invoked the menu with the mouse) then no quit occurs and @code{x-popup-menu} returns @code{nil}. @end defun @strong{Usage note:} Don't use @code{x-popup-menu} to display a menu if you could do the job with a prefix key defined with a menu keymap. If you use a menu keymap to implement a menu, @kbd{C-h c} and @kbd{C-h a} can see the individual items in that menu and provide help for them. If instead you implement the menu by defining a command that calls @code{x-popup-menu}, the help facilities cannot know what happens inside that command, so they cannot give any help for the menu's items. The menu bar mechanism, which lets you switch between submenus by moving the mouse, cannot look within the definition of a command to see that it calls @code{x-popup-menu}. Therefore, if you try to implement a submenu using @code{x-popup-menu}, it cannot work with the menu bar in an integrated fashion. This is why all menu bar submenus are implemented with menu keymaps within the parent menu, and never with @code{x-popup-menu}. @xref{Menu Bar}. If you want a menu bar submenu to have contents that vary, you should still use a menu keymap to implement it. To make the contents vary, add a hook function to @code{menu-bar-update-hook} to update the contents of the menu keymap as necessary. @node Dialog Boxes @section Dialog Boxes @cindex dialog boxes A dialog box is a variant of a pop-up menu---it looks a little different, it always appears in the center of a frame, and it has just one level and one or more buttons. The main use of dialog boxes is for asking questions that the user can answer with ``yes'', ``no'', and a few other alternatives. With a single button, they can also force the user to acknowledge important information. The functions @code{y-or-n-p} and @code{yes-or-no-p} use dialog boxes instead of the keyboard, when called from commands invoked by mouse clicks. @defun x-popup-dialog position contents &optional header This function displays a pop-up dialog box and returns an indication of what selection the user makes. The argument @var{contents} specifies the alternatives to offer; it has this format: @example (@var{title} (@var{string} . @var{value})@dots{}) @end example @noindent which looks like the list that specifies a single pane for @code{x-popup-menu}. The return value is @var{value} from the chosen alternative. As for @code{x-popup-menu}, an element of the list may be just a string instead of a cons cell @code{(@var{string} . @var{value})}. That makes a box that cannot be selected. If @code{nil} appears in the list, it separates the left-hand items from the right-hand items; items that precede the @code{nil} appear on the left, and items that follow the @code{nil} appear on the right. If you don't include a @code{nil} in the list, then approximately half the items appear on each side. Dialog boxes always appear in the center of a frame; the argument @var{position} specifies which frame. The possible values are as in @code{x-popup-menu}, but the precise coordinates or the individual window don't matter; only the frame matters. If @var{header} is non-@code{nil}, the frame title for the box is @samp{Information}, otherwise it is @samp{Question}. The former is used for @code{message-box} (@pxref{message-box}). In some configurations, Emacs cannot display a real dialog box; so instead it displays the same items in a pop-up menu in the center of the frame. If the user gets rid of the dialog box without making a valid choice, for instance using the window manager, then this produces a quit and @code{x-popup-dialog} does not return. @end defun @node Pointer Shape @section Pointer Shape @cindex pointer shape @cindex mouse pointer shape You can specify the mouse pointer style for particular text or images using the @code{pointer} text property, and for images with the @code{:pointer} and @code{:map} image properties. The values you can use in these properties are @code{text} (or @code{nil}), @code{arrow}, @code{hand}, @code{vdrag}, @code{hdrag}, @code{modeline}, and @code{hourglass}. @code{text} stands for the usual mouse pointer style used over text. Over void parts of the window (parts that do not correspond to any of the buffer contents), the mouse pointer usually uses the @code{arrow} style, but you can specify a different style (one of those above) by setting @code{void-text-area-pointer}. @defvar void-text-area-pointer This variable specifies the mouse pointer style for void text areas. These include the areas after the end of a line or below the last line in the buffer. The default is to use the @code{arrow} (non-text) pointer style. @end defvar You can specify what the @code{text} pointer style really looks like by setting the variable @code{x-pointer-shape}. @defvar x-pointer-shape This variable specifies the pointer shape to use ordinarily in the Emacs frame, for the @code{text} pointer style. @end defvar @defvar x-sensitive-text-pointer-shape This variable specifies the pointer shape to use when the mouse is over mouse-sensitive text. @end defvar These variables affect newly created frames. They do not normally affect existing frames; however, if you set the mouse color of a frame, that also installs the current value of those two variables. @xref{Color Parameters}. The values you can use, to specify either of these pointer shapes, are defined in the file @file{lisp/term/x-win.el}. Use @kbd{M-x apropos @key{RET} x-pointer @key{RET}} to see a list of them. @node Window System Selections @section Window System Selections @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 distinguished by @dfn{selection types}, represented in Emacs by symbols. X clients including Emacs can read or set the selection for any given type. @deffn Command x-set-selection type data This function sets a ``selection'' in the X server. It takes two arguments: a selection type @var{type}, and the value to assign to it, @var{data}. If @var{data} is @code{nil}, it means to clear out the selection. Otherwise, @var{data} may be a string, a symbol, an integer (or a cons of two integers or list of two integers), an overlay, or a cons of two markers pointing to the same buffer. An overlay or a pair of markers stands for text in the overlay or between the markers. The argument @var{data} may also be a vector of valid non-vector selection values. Each possible @var{type} has its own selection value, which changes independently. The usual values of @var{type} are @code{PRIMARY}, @code{SECONDARY} and @code{CLIPBOARD}; these are symbols with upper-case names, in accord with X Window System conventions. If @var{type} is @code{nil}, that stands for @code{PRIMARY}. This function returns @var{data}. @end deffn @defun x-get-selection &optional type data-type This function accesses selections set up by Emacs or by other X clients. It takes two optional arguments, @var{type} and @var{data-type}. The default for @var{type}, the selection type, is @code{PRIMARY}. The @var{data-type} argument specifies the form of data conversion to use, to convert the raw data obtained from another X client into Lisp data. Meaningful values include @code{TEXT}, @code{STRING}, @code{UTF8_STRING}, @code{TARGETS}, @code{LENGTH}, @code{DELETE}, @code{FILE_NAME}, @code{CHARACTER_POSITION}, @code{NAME}, @code{LINE_NUMBER}, @code{COLUMN_NUMBER}, @code{OWNER_OS}, @code{HOST_NAME}, @code{USER}, @code{CLASS}, @code{ATOM}, and @code{INTEGER}. (These are symbols with upper-case names in accord with X conventions.) The default for @var{data-type} is @code{STRING}. @end defun @cindex cut buffer The X server also has a set of eight numbered @dfn{cut buffers} which can store text or other data being moved between applications. Cut buffers are considered obsolete, but Emacs supports them for the sake of X clients that still use them. Cut buffers are numbered from 0 to 7. @defun x-get-cut-buffer &optional n This function returns the contents of cut buffer number @var{n}. If omitted @var{n} defaults to 0. @end defun @defun x-set-cut-buffer string &optional push @anchor{Definition of x-set-cut-buffer} This function stores @var{string} into the first cut buffer (cut buffer 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 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-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 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. @cindex scrap support (for Mac OS) On Mac OS, selection-like data transfer between applications is performed through a mechanism called @dfn{scraps}. The clipboard is a particular scrap named @code{com.apple.scrap.clipboard}. Types of scrap data are called @dfn{scrap flavor types}, which are identified by four-char codes such as @code{TEXT}. Emacs associates a selection with a scrap, and a selection type with a scrap flavor type via @code{mac-scrap-name} and @code{mac-ostype} properties, respectively. @example (get 'CLIPBOARD 'mac-scrap-name) @result{} "com.apple.scrap.clipboard" (get 'com.apple.traditional-mac-plain-text 'mac-ostype) @result{} "TEXT" @end example Conventionally, selection types for scrap flavor types on Mac OS have the form of @acronym{UTI, Uniform Type Identifier} such as @code{com.apple.traditional-mac-plain-text}, @code{public.utf16-plain-text}, and @code{public.file-url}. @defopt x-select-enable-clipboard If this is non-@code{nil}, the Emacs yank functions consult the clipboard before the primary selection, and the kill functions store in the clipboard as well as the primary selection. Otherwise they do not access the clipboard at all. The default is @code{nil} on most systems, but @code{t} on MS-Windows and Mac. @end defopt @node Drag and Drop @section Drag and Drop @vindex x-dnd-test-function @vindex x-dnd-known-types When a user drags something from another application over Emacs, that other application expects Emacs to tell it if Emacs can handle the data that is dragged. The variable @code{x-dnd-test-function} is used by Emacs to determine what to reply. The default value is @code{x-dnd-default-test-function} which accepts drops if the type of the data to be dropped is present in @code{x-dnd-known-types}. You can customize @code{x-dnd-test-function} and/or @code{x-dnd-known-types} if you want Emacs to accept or reject drops based on some other criteria. @vindex x-dnd-types-alist If you want to change the way Emacs handles drop of different types or add a new type, customize @code{x-dnd-types-alist}. This requires detailed knowledge of what types other applications use for drag and drop. @vindex dnd-protocol-alist When an URL is dropped on Emacs it may be a file, but it may also be another URL type (ftp, http, etc.). Emacs first checks @code{dnd-protocol-alist} to determine what to do with the URL. If there is no match there and if @code{browse-url-browser-function} is an alist, Emacs looks for a match there. If no match is found the text for the URL is inserted. If you want to alter Emacs behavior, you can customize these variables. @node Color Names @section Color Names @cindex color names @cindex specify color @cindex numerical RGB color specification A color name is text (usually in a string) that specifies a color. Symbolic names such as @samp{black}, @samp{white}, @samp{red}, etc., are allowed; use @kbd{M-x list-colors-display} to see a list of defined names. You can also specify colors numerically in forms such as @samp{#@var{rgb}} and @samp{RGB:@var{r}/@var{g}/@var{b}}, where @var{r} specifies the red level, @var{g} specifies the green level, and @var{b} specifies the blue level. You can use either one, two, three, or four hex digits for @var{r}; then you must use the same number of hex digits for all @var{g} and @var{b} as well, making either 3, 6, 9 or 12 hex digits in all. (See the documentation of the X Window System for more details about numerical RGB specification of colors.) These functions provide a way to determine which color names are 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 This function reports whether a color name is meaningful. It returns @code{t} if so; otherwise, @code{nil}. The argument @var{frame} says which frame's display to ask about; if @var{frame} is omitted or @code{nil}, the selected frame is used. 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 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 @defun defined-colors &optional frame This function returns a list of the color names that are defined and supported on frame @var{frame} (default, the selected frame). If @var{frame} does not support colors, the value is @code{nil}. @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 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 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. If @var{color} is not a valid color name, this function returns @code{nil}. @end defun @defun color-values color &optional frame @cindex rgb value This function returns a value that describes what @var{color} should ideally look like on @var{frame}. If @var{color} is defined, the value is a list of three integers, which give the amount of red, the amount of green, and the amount of blue. Each integer ranges in principle from 0 to 65535, but some displays may not use the full range. This three-element list is called the @dfn{rgb values} of the color. If @var{color} is not defined, the value is @code{nil}. @example (color-values "black") @result{} (0 0 0) (color-values "white") @result{} (65280 65280 65280) (color-values "red") @result{} (65280 0 0) (color-values "pink") @result{} (65280 49152 51968) (color-values "hungry") @result{} nil @end example The color values are returned for @var{frame}'s display. If @var{frame} is omitted or @code{nil}, the information is returned for the selected frame's display. If the frame cannot display colors, the value is @code{nil}. @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 @node Text Terminal Colors @section Text Terminal Colors @cindex colors on text-only terminals Text-only 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. Several of these functions use or return @dfn{rgb values}, described in @ref{Color Names}. 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{frame} argument has no effect. @defun tty-color-define name number &optional rgb frame This function associates the color name @var{name} with color number @var{number} on the terminal. The optional argument @var{rgb}, if specified, is an rgb value, a list of three numbers that specify what the color actually looks like. If you do not specify @var{rgb}, then this color cannot be used by @code{tty-color-approximate} to approximate other colors, because Emacs will not know what it looks like. @end defun @defun tty-color-clear &optional frame This function clears the table of defined colors for a text-only terminal. @end defun @defun tty-color-alist &optional frame 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 name, @var{number} is the number used to specify it to the terminal. If present, @var{rgb} is a list of three color values (for red, green, and blue) that says what the color actually looks like. @end defun @defun tty-color-approximate rgb &optional frame This function finds the closest color, among the known colors supported for @var{display}, to that described by the rgb value @var{rgb} (a list of color values). The return value is an element of @code{tty-color-alist}. @end defun @defun tty-color-translate color &optional frame This function finds the closest color to @var{color} among the known colors supported for @var{display} and returns its index (an integer). If the name @var{color} is not defined, the value is @code{nil}. @end defun @node Resources @section X Resources @defun x-get-resource attribute class &optional component subclass The function @code{x-get-resource} retrieves a resource value from the X Window defaults database. Resources are indexed by a combination of a @dfn{key} and a @dfn{class}. This function searches using a key of the form @samp{@var{instance}.@var{attribute}} (where @var{instance} is the name under which Emacs was invoked), and using @samp{Emacs.@var{class}} as the class. The optional arguments @var{component} and @var{subclass} add to the key and the class, respectively. You must specify both of them or neither. If you specify them, the key is @samp{@var{instance}.@var{component}.@var{attribute}}, and the class is @samp{Emacs.@var{class}.@var{subclass}}. @end defun @defvar x-resource-class This variable specifies the application name that @code{x-get-resource} should look up. The default value is @code{"Emacs"}. You can examine X resources for application names other than ``Emacs'' by binding this variable to some other string, around a call to @code{x-get-resource}. @end defvar @defvar x-resource-name This variable specifies the instance name that @code{x-get-resource} should look up. The default value is the name Emacs was invoked with, or the value specified with the @samp{-name} or @samp{-rn} switches. @end defvar To illustrate some of the above, suppose that you have the line: @example xterm.vt100.background: yellow @end example @noindent in your X resources file (whose name is usually @file{~/.Xdefaults} or @file{~/.Xresources}). Then: @example @group (let ((x-resource-class "XTerm") (x-resource-name "xterm")) (x-get-resource "vt100.background" "VT100.Background")) @result{} "yellow" @end group @group (let ((x-resource-class "XTerm") (x-resource-name "xterm")) (x-get-resource "background" "VT100" "vt100" "Background")) @result{} "yellow" @end group @end example @xref{X Resources,, X Resources, emacs, The GNU Emacs Manual}. @node Display Feature Testing @section Display Feature Testing @cindex display feature testing 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 ordinarily 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, @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 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 @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-mouse-p &optional display @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 @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 This function returns @code{t} if the screen can display shades of gray. (All color displays can do this.) @end defun @defun display-supports-face-attributes-p attributes &optional display @anchor{Display Face Attribute Testing} 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 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 display-screens &optional display This function returns the number of screens associated with the display. @end defun @defun display-pixel-height &optional display This function returns the height of the screen in pixels. On a character terminal, it gives the height in characters. @end defun @defun display-mm-height &optional display This function returns the height of the screen in millimeters, or @code{nil} if Emacs cannot get that information. @end defun @defun display-pixel-width &optional display This function returns the width of the screen in pixels. On a character terminal, it gives the width in characters. @end defun @defun display-mm-width &optional display This function returns the width of the screen in millimeters, or @code{nil} if Emacs cannot get that information. @end defun @defun display-backing-store &optional display 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}. The function can also return @code{nil} when the question is inapplicable to a certain kind of display. @end defun @defun display-save-under &optional display This function returns non-@code{nil} if the display supports the 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 display-planes &optional display 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 colors supported. @end defun @defun display-visual-class &optional display 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 display-color-cells &optional display This function returns the number of color cells the screen supports. @end defun 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. The value is a list of three integers: the major and minor version numbers of the X protocol, and the distributor-specific release number of the X server software itself. @end defun @defun x-server-vendor &optional display This function returns the ``vendor'' that provided the X server software (as a string). Really this means whoever distributes the X server. When the developers of X labelled software distributors as ``vendors'', they showed their false assumption that no system could ever be developed and distributed noncommercially. @end defun @ignore @defvar x-no-window-manager This variable's value is @code{t} if no X window manager is in use. @end defvar @end ignore @ignore @item The functions @code{x-pixel-width} and @code{x-pixel-height} return the width and height of an X Window frame, measured in pixels. @end ignore @ignore arch-tag: 94977df6-3dca-4730-b57b-c6329e9282ba @end ignore