[Emacs-diffs] Changes to windows.texi

[Glenn Morris]

CVSROOT:        /sources/emacs
Module name:    emacs
Changes by:     Glenn Morris <gm>       07/09/06 04:24:30

Index: windows.texi
===================================================================
RCS file: windows.texi
diff -N windows.texi
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ windows.texi        6 Sep 2007 04:24:30 -0000       1.1
@@ -0,0 +1,2446 @@
address@hidden -*-texinfo-*-
address@hidden This is part of the GNU Emacs Lisp Reference Manual.
address@hidden Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 
2001,
address@hidden   2002, 2003, 2004, 2005, 2006, 2007  Free Software Foundation, 
Inc.
address@hidden See the file elisp.texi for copying conditions.
address@hidden ../info/windows
address@hidden Windows, Frames, Buffers, Top
address@hidden Windows
+
+  This chapter describes most of the functions and variables related to
+Emacs windows.  See @ref{Display}, for information on how text is
+displayed in windows.
+
address@hidden
+* Basic Windows::           Basic information on using windows.
+* Splitting Windows::       Splitting one window into two windows.
+* Deleting Windows::        Deleting a window gives its space to other windows.
+* Selecting Windows::       The selected window is the one that you edit in.
+* Cyclic Window Ordering::  Moving around the existing windows.
+* Buffers and Windows::     Each window displays the contents of a buffer.
+* Displaying Buffers::      Higher-level functions for displaying a buffer
+                              and choosing a window for it.
+* Choosing Window::        How to choose a window for displaying a buffer.
+* Window Point::            Each window has its own location of point.
+* Window Start::            The display-start position controls which text
+                              is on-screen in the window.
+* Textual Scrolling::       Moving text up and down through the window.
+* Vertical Scrolling::      Moving the contents up and down on the window.
+* Horizontal Scrolling::    Moving the contents sideways on the window.
+* Size of Window::          Accessing the size of a window.
+* Resizing Windows::        Changing the size of a window.
+* Coordinates and Windows:: Converting coordinates to windows.
+* Window Tree::             The layout and sizes of all windows in a frame.
+* Window Configurations::   Saving and restoring the state of the screen.
+* Window Hooks::            Hooks for scrolling, window size changes,
+                              redisplay going past a certain point,
+                              or window configuration changes.
address@hidden menu
+
address@hidden Basic Windows
address@hidden Basic Concepts of Emacs Windows
address@hidden window
address@hidden selected window
+
+  A @dfn{window} in Emacs is the physical area of the screen in which a
+buffer is displayed.  The term is also used to refer to a Lisp object that
+represents that screen area in Emacs Lisp.  It should be
+clear from the context which is meant.
+
+  Emacs groups windows into frames.  A frame represents an area of
+screen available for Emacs to use.  Each frame always contains at least
+one window, but you can subdivide it vertically or horizontally into
+multiple nonoverlapping Emacs windows.
+
+  In each frame, at any time, one and only one window is designated as
address@hidden within the frame}.  The frame's cursor appears in that
+window, but the other windows have ``non-selected'' cursors, normally
+less visible.  At any time, one frame is the selected frame; and the
+window selected within that frame is @dfn{the selected window}.  The
+selected window's buffer is usually the current buffer (except when
address@hidden has been used).  @xref{Current Buffer}.
+
address@hidden cursor-in-non-selected-windows
+If this variable is @code{nil}, Emacs displays only one cursor,
+in the selected window.  Other windows have no cursor at all.
address@hidden defvar
+
+  For practical purposes, a window exists only while it is displayed in
+a frame.  Once removed from the frame, the window is effectively deleted
+and should not be used, @emph{even though there may still be references
+to it} from other Lisp objects.  Restoring a saved window configuration
+is the only way for a window no longer on the screen to come back to
+life.  (@xref{Deleting Windows}.)
+
+  Each window has the following attributes:
+
address@hidden @bullet
address@hidden
+containing frame
+
address@hidden
+window height
+
address@hidden
+window width
+
address@hidden
+window edges with respect to the screen or frame
+
address@hidden
+the buffer it displays
+
address@hidden
+position within the buffer at the upper left of the window
+
address@hidden
+amount of horizontal scrolling, in columns
+
address@hidden
+point
+
address@hidden
+the mark
+
address@hidden
+how recently the window was selected
+
address@hidden
+fringe settings
+
address@hidden
+display margins
+
address@hidden
+scroll-bar settings
address@hidden itemize
+
address@hidden multiple windows
+  Users create multiple windows so they can look at several buffers at
+once.  Lisp libraries use multiple windows for a variety of reasons, but
+most often to display related information.  In Rmail, for example, you
+can move through a summary buffer in one window while the other window
+shows messages one at a time as they are reached.
+
+  The meaning of ``window'' in Emacs is similar to what it means in the
+context of general-purpose window systems such as X, but not identical.
+The X Window System places X windows on the screen; Emacs uses one or
+more X windows as frames, and subdivides them into
+Emacs windows.  When you use Emacs on a character-only terminal, Emacs
+treats the whole terminal screen as one frame.
+
address@hidden terminal screen
address@hidden screen of terminal
address@hidden tiled windows
+  Most window systems support arbitrarily located overlapping windows.
+In contrast, Emacs windows are @dfn{tiled}; they never overlap, and
+together they fill the whole screen or frame.  Because of the way in
+which Emacs creates new windows and resizes them, not all conceivable
+tilings of windows on an Emacs frame are actually possible.
address@hidden Windows}, and @ref{Size of Window}.
+
+  @xref{Display}, for information on how the contents of the
+window's buffer are displayed in the window.
+
address@hidden windowp object
+This function returns @code{t} if @var{object} is a window.
address@hidden defun
+
address@hidden Splitting Windows
address@hidden Splitting Windows
address@hidden splitting windows
address@hidden window splitting
+
+  The functions described here are the primitives used to split a window
+into two windows.  Two higher level functions sometimes split a window,
+but not always: @code{pop-to-buffer} and @code{display-buffer}
+(@pxref{Displaying Buffers}).
+
+  The functions described here do not accept a buffer as an argument.
+The two ``halves'' of the split window initially display the same buffer
+previously visible in the window that was split.
+
address@hidden Command split-window &optional window size horizontal
+This function splits a new window out of @var{window}'s screen area.
+It returns the new window.
+
+If @var{horizontal} is address@hidden, then @var{window} splits into
+two side by side windows.  The original window @var{window} keeps the
+leftmost @var{size} columns, and gives the rest of the columns to the
+new window.  Otherwise, it splits into windows one above the other, and
address@hidden keeps the upper @var{size} lines and gives the rest of the
+lines to the new window.  The original window is therefore the
+left-hand or upper of the two, and the new window is the right-hand or
+lower.
+
+If @var{window} is omitted or @code{nil}, that stands for the selected
+window.  When you split the selected window, it remains selected.
+
+If @var{size} is omitted or @code{nil}, then @var{window} is divided
+evenly into two parts.  (If there is an odd line, it is allocated to
+the new window.)  When @code{split-window} is called interactively,
+all its arguments are @code{nil}.
+
+If splitting would result in making a window that is smaller than
address@hidden or @code{window-min-width}, the function
+signals an error and does not split the window at all.
+
+The following example starts with one window on a screen that is 50
+lines high by 80 columns wide; then it splits the window.
+
address@hidden
address@hidden
+(setq w (selected-window))
+     @result{} #<window 8 on windows.texi>
+(window-edges)          ; @r{Edges in order:}
+     @result{} (0 0 80 50)     ;   @r{left--top--right--bottom}
address@hidden group
+
address@hidden
+;; @r{Returns window created}
+(setq w2 (split-window w 15))
+     @result{} #<window 28 on windows.texi>
address@hidden group
address@hidden
+(window-edges w2)
+     @result{} (0 15 80 50)    ; @r{Bottom window;}
+                        ;   @r{top is line 15}
address@hidden group
address@hidden
+(window-edges w)
+     @result{} (0 0 80 15)     ; @r{Top window}
address@hidden group
address@hidden smallexample
+
+The screen looks like this:
+
address@hidden
address@hidden
+         __________
+        |          |  line 0
+        |    w     |
+        |__________|
+        |          |  line 15
+        |    w2    |
+        |__________|
+                      line 50
+ column 0   column 80
address@hidden group
address@hidden smallexample
+
+Next, split the top window horizontally:
+
address@hidden
address@hidden
+(setq w3 (split-window w 35 t))
+     @result{} #<window 32 on windows.texi>
address@hidden group
address@hidden
+(window-edges w3)
+     @result{} (35 0 80 15)  ; @r{Left edge at column 35}
address@hidden group
address@hidden
+(window-edges w)
+     @result{} (0 0 35 15)   ; @r{Right edge at column 35}
address@hidden group
address@hidden
+(window-edges w2)
+     @result{} (0 15 80 50)  ; @r{Bottom window unchanged}
address@hidden group
address@hidden smallexample
+
address@hidden 3000
+Now the screen looks like this:
+
address@hidden
address@hidden
+     column 35
+         __________
+        |   |      |  line 0
+        | w |  w3  |
+        |___|______|
+        |          |  line 15
+        |    w2    |
+        |__________|
+                      line 50
+ column 0   column 80
address@hidden group
address@hidden smallexample
+
+Normally, Emacs indicates the border between two side-by-side windows
+with a scroll bar (@pxref{Layout Parameters,Scroll Bars}) or @samp{|}
+characters.  The display table can specify alternative border
+characters; see @ref{Display Tables}.
address@hidden deffn
+
address@hidden Command split-window-vertically &optional size
+This function splits the selected window into two windows, one above the
+other, leaving the upper of the two windows selected, with @var{size}
+lines.  (If @var{size} is negative, then the lower of the two windows
+gets @minus{} @var{size} lines and the upper window gets the rest, but
+the upper window is still the one selected.)  However, if
address@hidden (see below) is @code{nil}, then either
+window can be selected.
+
+In other respects, this function is similar to @code{split-window}.
+In particular, the upper window is the original one and the return
+value is the new, lower window.
address@hidden deffn
+
address@hidden split-window-keep-point
+If this variable is address@hidden (the default), then
address@hidden behaves as described above.
+
+If it is @code{nil}, then @code{split-window-vertically} adjusts point
+in each of the two windows to avoid scrolling.  (This is useful on
+slow terminals.)  It selects whichever window contains the screen line
+that point was previously on.
+
+This variable only affects the behavior of @code{split-window-vertically}.
+It has no effect on the other functions described here.
address@hidden defopt
+
address@hidden Command split-window-horizontally &optional size
+This function splits the selected window into two windows
+side-by-side, leaving the selected window on the left with @var{size}
+columns.  If @var{size} is negative, the rightmost window gets
address@hidden @var{size} columns, but the leftmost window still remains
+selected.
+
+This function is basically an interface to @code{split-window}.
+You could define a simplified version of the function like this:
+
address@hidden
address@hidden
+(defun split-window-horizontally (&optional arg)
+  "Split selected window into two windows, side by side..."
+  (interactive "P")
address@hidden group
address@hidden
+  (let ((size (and arg (prefix-numeric-value arg))))
+    (and size (< size 0)
+        (setq size (+ (window-width) size)))
+    (split-window nil size t)))
address@hidden group
address@hidden smallexample
address@hidden deffn
+
address@hidden one-window-p &optional no-mini all-frames
+This function returns address@hidden if there is only one window.  The
+argument @var{no-mini}, if address@hidden, means don't count the
+minibuffer even if it is active; otherwise, the minibuffer window is
+counted when it is active.
+
+The argument @var{all-frames} specifies which frames to consider.  Here
+are the possible values and their meanings:
+
address@hidden @asis
address@hidden @code{nil}
+Count the windows in the selected frame, plus the minibuffer used
+by that frame even if it lies in some other frame.
+
address@hidden @code{t}
+Count all windows in all existing frames.
+
address@hidden @code{visible}
+Count all windows in all visible frames.
+
address@hidden 0
+Count all windows in all visible or iconified frames.
+
address@hidden anything else
+Count precisely the windows in the selected frame, and no others.
address@hidden table
address@hidden defun
+
address@hidden Deleting Windows
address@hidden Deleting Windows
address@hidden deleting windows
+
+A window remains visible on its frame unless you @dfn{delete} it by
+calling certain functions that delete windows.  A deleted window cannot
+appear on the screen, but continues to exist as a Lisp object until
+there are no references to it.  There is no way to cancel the deletion
+of a window aside from restoring a saved window configuration
+(@pxref{Window Configurations}).  Restoring a window configuration also
+deletes any windows that aren't part of that configuration.
+
+  When you delete a window, the space it took up is given to one
+adjacent sibling.
+
address@hidden Emacs 19 feature
address@hidden window-live-p window
+This function returns @code{nil} if @var{window} is deleted, and
address@hidden otherwise.
+
address@hidden:} Erroneous information or fatal errors may result from
+using a deleted window as if it were live.
address@hidden defun
+
address@hidden Command delete-window &optional window
+This function removes @var{window} from display, and returns @code{nil}.
+If @var{window} is omitted, then the selected window is deleted.  An
+error is signaled if there is only one window when @code{delete-window}
+is called.
address@hidden deffn
+
address@hidden Command delete-other-windows &optional window
+This function makes @var{window} the only window on its frame, by
+deleting the other windows in that frame.  If @var{window} is omitted or
address@hidden, then the selected window is used by default.
+
+The return value is @code{nil}.
address@hidden deffn
+
address@hidden Command delete-windows-on buffer-or-name &optional frame
+This function deletes all windows showing @var{buffer-or-name}.  If
+there are no windows showing @var{buffer-or-name}, it does nothing.
address@hidden must be a buffer or the name of an existing
+buffer.
+
address@hidden operates frame by frame.  If a frame has
+several windows showing different buffers, then those showing
address@hidden are removed, and the others expand to fill the
+space.  If all windows in some frame are showing @var{buffer-or-name}
+(including the case where there is only one window), then the frame
+winds up with a single window showing another buffer chosen with
address@hidden  @xref{The Buffer List}.
+
+The argument @var{frame} controls which frames to operate on.  This
+function does not use it in quite the same way as the other functions
+which scan all windows; specifically, the values @code{t} and @code{nil}
+have the opposite of their meanings in other functions.  Here are the
+full details:
+
address@hidden @bullet
address@hidden
+If it is @code{nil}, operate on all frames.
address@hidden
+If it is @code{t}, operate on the selected frame.
address@hidden
+If it is @code{visible}, operate on all visible frames.
address@hidden
+If it is 0, operate on all visible or iconified frames.
address@hidden
+If it is a frame, operate on that frame.
address@hidden itemize
+
+This function always returns @code{nil}.
address@hidden deffn
+
address@hidden Selecting Windows
address@hidden Selecting Windows
address@hidden selecting a window
+
+  When a window is selected, the buffer in the window becomes the current
+buffer, and the cursor will appear in it.
+
address@hidden selected-window
+This function returns the selected window.  This is the window in
+which the cursor appears and to which many commands apply.
address@hidden defun
+
address@hidden select-window window &optional norecord
+This function makes @var{window} the selected window.  The cursor then
+appears in @var{window} (on redisplay).  Unless @var{window} was
+already selected, @code{select-window} makes @var{window}'s buffer the
+current buffer.
+
+Normally @var{window}'s selected buffer is moved to the front of the
+buffer list, but if @var{norecord} is address@hidden, the buffer list
+order is unchanged.
+
+The return value is @var{window}.
+
address@hidden
address@hidden
+(setq w (next-window))
+(select-window w)
+     @result{} #<window 65 on windows.texi>
address@hidden group
address@hidden example
address@hidden defun
+
address@hidden save-selected-window address@hidden
+This macro records the selected frame, as well as the selected window
+of each frame, executes @var{forms} in sequence, then restores the
+earlier selected frame and windows.  It also saves and restores the
+current buffer.  It returns the value of the last form in @var{forms}.
+
+This macro does not save or restore anything about the sizes,
+arrangement or contents of windows; therefore, if the @var{forms}
+change them, the change persists.  If the previously selected window
+of some frame is no longer live at the time of exit from @var{forms},
+that frame's selected window is left alone.  If the previously
+selected window is no longer live, then whatever window is selected at
+the end of @var{forms} remains selected.
address@hidden defmac
+
address@hidden with-selected-window window address@hidden
+This macro selects @var{window} (without changing the buffer list),
+executes @var{forms} in sequence, then restores the previously
+selected window and current buffer.  It is just like
address@hidden, except that it explicitly selects
address@hidden, also without altering the buffer list sequence.
address@hidden defmac
+
address@hidden finding windows
+  The following functions choose one of the windows on the screen,
+offering various criteria for the choice.
+
address@hidden get-lru-window &optional frame dedicated
+This function returns the window least recently ``used'' (that is,
+selected).  If any full-width windows are present, it only considers
+these.  The selected window is always the most recently used window.
+
+The selected window can be the least recently used window if it is the
+only window.  A newly created window becomes the least recently used
+window until it is selected.  A minibuffer window is never a
+candidate.  Dedicated windows are never candidates unless the
address@hidden argument is address@hidden, so if all
+existing windows are dedicated, the value is @code{nil}.
+
+The argument @var{frame} controls which windows are considered.
+
address@hidden @bullet
address@hidden
+If it is @code{nil}, consider windows on the selected frame.
address@hidden
+If it is @code{t}, consider windows on all frames.
address@hidden
+If it is @code{visible}, consider windows on all visible frames.
address@hidden
+If it is 0, consider windows on all visible or iconified frames.
address@hidden
+If it is a frame, consider windows on that frame.
address@hidden itemize
address@hidden defun
+
address@hidden get-largest-window &optional frame dedicated
+This function returns the window with the largest area (height times
+width).  If there are no side-by-side windows, then this is the window
+with the most lines.  A minibuffer window is never a candidate.
+Dedicated windows are never candidates unless the
address@hidden argument is address@hidden, so if all existing windows
+are dedicated, the value is @code{nil}.
+
+If there are two candidate windows of the same size, this function
+prefers the one that comes first in the cyclic ordering of windows
+(see following section), starting from the selected window.
+
+The argument @var{frame} controls which set of windows to
+consider.  See @code{get-lru-window}, above.
address@hidden defun
+
address@hidden window that satisfies a predicate
address@hidden conditional selection of windows
address@hidden get-window-with-predicate predicate &optional minibuf all-frames 
default
+This function returns a window satisfying @var{predicate}.  It cycles
+through all visible windows using @code{walk-windows} (@pxref{Cyclic
+Window Ordering}), calling @var{predicate} on each one of them
+with that window as its argument.  The function returns the first
+window for which @var{predicate} returns a address@hidden value; if
+that never happens, it returns @var{default}.
+
+The optional arguments @var{minibuf} and @var{all-frames} specify the
+set of windows to include in the scan.  See the description of
address@hidden in @ref{Cyclic Window Ordering}, for details.
address@hidden defun
+
address@hidden Cyclic Window Ordering
address@hidden  node-name,  next,  previous,  up
address@hidden Cyclic Ordering of Windows
address@hidden cyclic ordering of windows
address@hidden ordering of windows, cyclic
address@hidden window ordering, cyclic
+
+  When you use the command @kbd{C-x o} (@code{other-window}) to select
+the next window, it moves through all the windows on the screen in a
+specific cyclic order.  For any given configuration of windows, this
+order never varies.  It is called the @dfn{cyclic ordering of windows}.
+
+  This ordering generally goes from top to bottom, and from left to
+right.  But it may go down first or go right first, depending on the
+order in which the windows were split.
+
+  If the first split was vertical (into windows one above each other),
+and then the subwindows were split horizontally, then the ordering is
+left to right in the top of the frame, and then left to right in the
+next lower part of the frame, and so on.  If the first split was
+horizontal, the ordering is top to bottom in the left part, and so on.
+In general, within each set of siblings at any level in the window tree,
+the order is left to right, or top to bottom.
+
address@hidden next-window &optional window minibuf all-frames
address@hidden minibuffer window, and @code{next-window}
+This function returns the window following @var{window} in the cyclic
+ordering of windows.  This is the window that @kbd{C-x o} would select
+if typed when @var{window} is selected.  If @var{window} is the only
+window visible, then this function returns @var{window}.  If omitted,
address@hidden defaults to the selected window.
+
+The value of the argument @var{minibuf} determines whether the
+minibuffer is included in the window order.  Normally, when
address@hidden is @code{nil}, the minibuffer is included if it is
+currently active; this is the behavior of @kbd{C-x o}.  (The minibuffer
+window is active while the minibuffer is in use.  @xref{Minibuffers}.)
+
+If @var{minibuf} is @code{t}, then the cyclic ordering includes the
+minibuffer window even if it is not active.
+
+If @var{minibuf} is neither @code{t} nor @code{nil}, then the minibuffer
+window is not included even if it is active.
+
+The argument @var{all-frames} specifies which frames to consider.  Here
+are the possible values and their meanings:
+
address@hidden @asis
address@hidden @code{nil}
+Consider all the windows in @var{window}'s frame, plus the minibuffer
+used by that frame even if it lies in some other frame.  If the
+minibuffer counts (as determined by @var{minibuf}), then all windows on
+all frames that share that minibuffer count too.
+
address@hidden @code{t}
+Consider all windows in all existing frames.
+
address@hidden @code{visible}
+Consider all windows in all visible frames.  (To get useful results, you
+must ensure @var{window} is in a visible frame.)
+
address@hidden 0
+Consider all windows in all visible or iconified frames.
+
address@hidden a frame
+Consider all windows on that frame.
+
address@hidden anything else
+Consider precisely the windows in @var{window}'s frame, and no others.
address@hidden table
+
+This example assumes there are two windows, both displaying the
+buffer @samp{windows.texi}:
+
address@hidden
address@hidden
+(selected-window)
+     @result{} #<window 56 on windows.texi>
address@hidden group
address@hidden
+(next-window (selected-window))
+     @result{} #<window 52 on windows.texi>
address@hidden group
address@hidden
+(next-window (next-window (selected-window)))
+     @result{} #<window 56 on windows.texi>
address@hidden group
address@hidden example
address@hidden defun
+
address@hidden previous-window &optional window minibuf all-frames
+This function returns the window preceding @var{window} in the cyclic
+ordering of windows.  The other arguments specify which windows to
+include in the cycle, as in @code{next-window}.
address@hidden defun
+
address@hidden Command other-window count &optional all-frames
+This function selects the @var{count}th following window in the cyclic
+order.  If count is negative, then it moves back @address@hidden
+windows in the cycle, rather than forward.  It returns @code{nil}.
+
+The argument @var{all-frames} has the same meaning as in
address@hidden, but the @var{minibuf} argument of @code{next-window}
+is always effectively @code{nil}.
+
+In an interactive call, @var{count} is the numeric prefix argument.
address@hidden deffn
+
address@hidden Emacs 19 feature
address@hidden walk-windows proc &optional minibuf all-frames
+This function cycles through all windows.  It calls the function
address@hidden once for each window, with the window as its sole
+argument.
+
+The optional arguments @var{minibuf} and @var{all-frames} specify the
+set of windows to include in the scan.  See @code{next-window}, above,
+for details.
address@hidden defun
+
address@hidden window-list &optional frame minibuf window
+This function returns a list of the windows on @var{frame}, starting
+with @var{window}.  If @var{frame} is @code{nil} or omitted,
address@hidden uses the selected frame instead; if @var{window} is
address@hidden or omitted, it uses the selected window.
+
+The value of @var{minibuf} determines if the minibuffer window is
+included in the result list.  If @var{minibuf} is @code{t}, the result
+always includes the minibuffer window.  If @var{minibuf} is @code{nil}
+or omitted, that includes the minibuffer window if it is active.  If
address@hidden is neither @code{nil} nor @code{t}, the result never
+includes the minibuffer window.
address@hidden defun
+
address@hidden Buffers and Windows
address@hidden Buffers and Windows
address@hidden examining windows
address@hidden windows, controlling precisely
address@hidden buffers, controlled in windows
+
+  This section describes low-level functions to examine windows or to
+display buffers in windows in a precisely controlled fashion.
address@hidden
+See the following section for
address@hidden iftex
address@hidden
address@hidden Buffers}, for
address@hidden ifnottex
+related functions that find a window to use and specify a buffer for it.
+The functions described there are easier to use than these, but they
+employ heuristics in choosing or creating a window; use these functions
+when you need complete control.
+
address@hidden set-window-buffer window buffer-or-name &optional keep-margins
+This function makes @var{window} display @var{buffer-or-name} as its
+contents.  It returns @code{nil}.  @var{buffer-or-name} must be a
+buffer, or the name of an existing buffer.  This is the fundamental
+primitive for changing which buffer is displayed in a window, and all
+ways of doing that call this function.
+
address@hidden
address@hidden
+(set-window-buffer (selected-window) "foo")
+     @result{} nil
address@hidden group
address@hidden example
+
+Normally, displaying @var{buffer} in @var{window} resets the window's
+display margins, fringe widths, scroll bar settings, and position
+based on the local variables of @var{buffer}.  However, if
address@hidden is address@hidden, the display margins and fringe
+widths of @var{window} remain unchanged.  @xref{Fringes}.
address@hidden defun
+
address@hidden buffer-display-count
+This buffer-local variable records the number of times a buffer is
+displayed in a window.  It is incremented each time
address@hidden is called for the buffer.
address@hidden defvar
+
address@hidden window-buffer &optional window
+This function returns the buffer that @var{window} is displaying.  If
address@hidden is omitted, this function returns the buffer for the
+selected window.
+
address@hidden
address@hidden
+(window-buffer)
+     @result{} #<buffer windows.texi>
address@hidden group
address@hidden example
address@hidden defun
+
address@hidden get-buffer-window buffer-or-name &optional all-frames
+This function returns a window currently displaying
address@hidden, or @code{nil} if there is none.  If there are
+several such windows, then the function returns the first one in the
+cyclic ordering of windows, starting from the selected window.
address@hidden Window Ordering}.
+
+The argument @var{all-frames} controls which windows to consider.
+
address@hidden @bullet
address@hidden
+If it is @code{nil}, consider windows on the selected frame.
address@hidden
+If it is @code{t}, consider windows on all frames.
address@hidden
+If it is @code{visible}, consider windows on all visible frames.
address@hidden
+If it is 0, consider windows on all visible or iconified frames.
address@hidden
+If it is a frame, consider windows on that frame.
address@hidden itemize
address@hidden defun
+
address@hidden get-buffer-window-list buffer-or-name &optional minibuf 
all-frames
+This function returns a list of all the windows currently displaying
address@hidden
+
+The two optional arguments work like the optional arguments of
address@hidden (@pxref{Cyclic Window Ordering}); they are @emph{not}
+like the single optional argument of @code{get-buffer-window}.  Perhaps
+we should change @code{get-buffer-window} in the future to make it
+compatible with the other functions.
address@hidden defun
+
address@hidden buffer-display-time
+This variable records the time at which a buffer was last made visible
+in a window.  It is always local in each buffer; each time
address@hidden is called, it sets this variable to
address@hidden(current-time)} in the specified buffer (@pxref{Time of Day}).
+When a buffer is first created, @code{buffer-display-time} starts out
+with the value @code{nil}.
address@hidden defvar
+
address@hidden Displaying Buffers
address@hidden Displaying Buffers in Windows
address@hidden switching to a buffer
address@hidden displaying a buffer
+
+  In this section we describe convenient functions that choose a window
+automatically and use it to display a specified buffer.  These functions
+can also split an existing window in certain circumstances.  We also
+describe variables that parameterize the heuristics used for choosing a
+window.
address@hidden
+See the preceding section for
address@hidden iftex
address@hidden
address@hidden and Windows}, for
address@hidden ifnottex
+low-level functions that give you more precise control.  All of these
+functions work by calling @code{set-window-buffer}.
+
+  Do not use the functions in this section in order to make a buffer
+current so that a Lisp program can access or modify it; they are too
+drastic for that purpose, since they change the display of buffers in
+windows, which would be gratuitous and surprise the user.  Instead, use
address@hidden and @code{save-current-buffer} (@pxref{Current
+Buffer}), which designate buffers as current for programmed access
+without affecting the display of buffers in windows.
+
address@hidden Command switch-to-buffer buffer-or-name &optional norecord
+This function makes @var{buffer-or-name} the current buffer, and also
+displays the buffer in the selected window.  This means that a human can
+see the buffer and subsequent keyboard commands will apply to it.
+Contrast this with @code{set-buffer}, which makes @var{buffer-or-name}
+the current buffer but does not display it in the selected window.
address@hidden Buffer}.
+
+If @var{buffer-or-name} does not identify an existing buffer, then a new
+buffer by that name is created.  The major mode for the new buffer is
+set according to the variable @code{default-major-mode}.  @xref{Auto
+Major Mode}.  If @var{buffer-or-name} is @code{nil},
address@hidden chooses a buffer using @code{other-buffer}.
+
+Normally the specified buffer is put at the front of the buffer list
+(both the selected frame's buffer list and the frame-independent buffer
+list).  This affects the operation of @code{other-buffer}.  However, if
address@hidden is address@hidden, this is not done.  @xref{The Buffer
+List}.
+
+The @code{switch-to-buffer} function is often used interactively, as
+the binding of @kbd{C-x b}.  It is also used frequently in programs.  It
+returns the buffer that it switched to.
address@hidden deffn
+
+The next two functions are similar to @code{switch-to-buffer}, except
+for the described features.
+
address@hidden Command switch-to-buffer-other-window buffer-or-name &optional 
norecord
+This function makes @var{buffer-or-name} the current buffer and
+displays it in a window not currently selected.  It then selects that
+window.  The handling of the buffer is the same as in
address@hidden
+
+The currently selected window is absolutely never used to do the job.
+If it is the only window, then it is split to make a distinct window for
+this purpose.  If the selected window is already displaying the buffer,
+then it continues to do so, but another window is nonetheless found to
+display it in as well.
+
+This function updates the buffer list just like @code{switch-to-buffer}
+unless @var{norecord} is address@hidden
address@hidden deffn
+
address@hidden pop-to-buffer buffer-or-name &optional other-window norecord
+This function makes @var{buffer-or-name} the current buffer and
+switches to it in some window, preferably not the window previously
+selected.  The ``popped-to'' window becomes the selected window within
+its frame.  The return value is the buffer that was switched to.
+If @var{buffer-or-name} is @code{nil}, that means to choose some
+other buffer, but you don't specify which.
+
+If the variable @code{pop-up-frames} is address@hidden,
address@hidden looks for a window in any visible frame already
+displaying the buffer; if there is one, it returns that window and makes
+it be selected within its frame.  If there is none, it creates a new
+frame and displays the buffer in it.
+
+If @code{pop-up-frames} is @code{nil}, then @code{pop-to-buffer}
+operates entirely within the selected frame.  (If the selected frame has
+just a minibuffer, @code{pop-to-buffer} operates within the most
+recently selected frame that was not just a minibuffer.)
+
+If the variable @code{pop-up-windows} is address@hidden, windows may
+be split to create a new window that is different from the original
+window.  For details, see @ref{Choosing Window}.
+
+If @var{other-window} is address@hidden, @code{pop-to-buffer} finds or
+creates another window even if @var{buffer-or-name} is already visible
+in the selected window.  Thus @var{buffer-or-name} could end up
+displayed in two windows.  On the other hand, if @var{buffer-or-name} is
+already displayed in the selected window and @var{other-window} is
address@hidden, then the selected window is considered sufficient display
+for @var{buffer-or-name}, so that nothing needs to be done.
+
+All the variables that affect @code{display-buffer} affect
address@hidden as well.  @xref{Choosing Window}.
+
+If @var{buffer-or-name} is a string that does not name an existing
+buffer, a buffer by that name is created.  The major mode for the new
+buffer is set according to the variable @code{default-major-mode}.
address@hidden Major Mode}.
+
+This function updates the buffer list just like @code{switch-to-buffer}
+unless @var{norecord} is address@hidden
address@hidden defun
+
address@hidden Command replace-buffer-in-windows buffer-or-name
+This function replaces @var{buffer-or-name} with some other buffer in all
+windows displaying it.  It chooses the other buffer with
address@hidden  In the usual applications of this function, you
+don't care which other buffer is used; you just want to make sure that
address@hidden is no longer displayed.
+
+This function returns @code{nil}.
address@hidden deffn
+
address@hidden Choosing Window
address@hidden Choosing a Window for Display
+
+  This section describes the basic facility that chooses a window to
+display a buffer address@hidden  All the higher-level
+functions and commands use this subroutine.  Here we describe how to use
address@hidden and how to customize it.
+
address@hidden Command display-buffer buffer-or-name &optional not-this-window 
frame
+This command makes @var{buffer-or-name} appear in some window, like
address@hidden, but it does not select that window and does not
+make the buffer current.  The identity of the selected window is
+unaltered by this function.  @var{buffer-or-name} must be a buffer, or
+the name of an existing buffer.
+
+If @var{not-this-window} is address@hidden, it means to display the
+specified buffer in a window other than the selected one, even if it is
+already on display in the selected window.  This can cause the buffer to
+appear in two windows at once.  Otherwise, if @var{buffer-or-name} is
+already being displayed in any window, that is good enough, so this
+function does nothing.
+
address@hidden returns the window chosen to display
address@hidden
+
+If the argument @var{frame} is address@hidden, it specifies which frames
+to check when deciding whether the buffer is already displayed.  If the
+buffer is already displayed in some window on one of these frames,
address@hidden simply returns that window.  Here are the possible
+values of @var{frame}:
+
address@hidden @bullet
address@hidden
+If it is @code{nil}, consider windows on the selected frame.
+(Actually, the last non-minibuffer frame.)
address@hidden
+If it is @code{t}, consider windows on all frames.
address@hidden
+If it is @code{visible}, consider windows on all visible frames.
address@hidden
+If it is 0, consider windows on all visible or iconified frames.
address@hidden
+If it is a frame, consider windows on that frame.
address@hidden itemize
+
+Precisely how @code{display-buffer} finds or creates a window depends on
+the variables described below.
address@hidden deffn
+
address@hidden display-buffer-reuse-frames
+If this variable is address@hidden, @code{display-buffer} searches
+existing frames for a window displaying the buffer.  If the buffer is
+already displayed in a window in some frame, @code{display-buffer} makes
+the frame visible and raises it, to use that window.  If the buffer is
+not already displayed, or if @code{display-buffer-reuse-frames} is
address@hidden, @code{display-buffer}'s behavior is determined by other
+variables, described below.
address@hidden defopt
+
address@hidden pop-up-windows
+This variable controls whether @code{display-buffer} makes new windows.
+If it is address@hidden and there is only one window, then that window
+is split.  If it is @code{nil}, then @code{display-buffer} does not
+split the single window, but uses it whole.
address@hidden defopt
+
address@hidden split-height-threshold
+This variable determines when @code{display-buffer} may split a window,
+if there are multiple windows.  @code{display-buffer} always splits the
+largest window if it has at least this many lines.  If the largest
+window is not this tall, it is split only if it is the sole window and
address@hidden is address@hidden
address@hidden defopt
+
address@hidden even-window-heights
+This variable determines if @code{display-buffer} should even out window
+heights if the buffer gets displayed in an existing window, above or
+beneath another existing window.  If @code{even-window-heights} is
address@hidden, the default, window heights will be evened out.  If
address@hidden is @code{nil}, the original window heights
+will be left alone.
address@hidden defopt
+
address@hidden Emacs 19 feature
address@hidden pop-up-frames
+This variable controls whether @code{display-buffer} makes new frames.
+If it is address@hidden, @code{display-buffer} looks for an existing
+window already displaying the desired buffer, on any visible frame.  If
+it finds one, it returns that window.  Otherwise it makes a new frame.
+The variables @code{pop-up-windows} and @code{split-height-threshold} do
+not matter if @code{pop-up-frames} is address@hidden
+
+If @code{pop-up-frames} is @code{nil}, then @code{display-buffer} either
+splits a window or reuses one.
+
address@hidden, for more information.
address@hidden defopt
+
address@hidden Emacs 19 feature
address@hidden pop-up-frame-function
+This variable specifies how to make a new frame if @code{pop-up-frames}
+is address@hidden
+
+Its value should be a function of no arguments.  When
address@hidden makes a new frame, it does so by calling that
+function, which should return a frame.  The default value of the
+variable is a function that creates a frame using parameters from
address@hidden
address@hidden defopt
+
address@hidden pop-up-frame-alist
+This variable holds an alist specifying frame parameters used when
address@hidden makes a new frame.  @xref{Frame Parameters}, for
+more information about frame parameters.
address@hidden defopt
+
address@hidden special-display-buffer-names
+A list of buffer names for buffers that should be displayed specially.
+If the buffer's name is in this list, @code{display-buffer} handles the
+buffer specially.
+
+By default, special display means to give the buffer a dedicated frame.
+
+If an element is a list, instead of a string, then the @sc{car} of the
+list is the buffer name, and the rest of the list says how to create
+the frame.  There are two possibilities for the rest of the list (its
address@hidden).  It can be an alist, specifying frame parameters, or it can
+contain a function and arguments to give to it.  (The function's first
+argument is always the buffer to be displayed; the arguments from the
+list come after that.)
+
+For example:
+
address@hidden
+(("myfile" (minibuffer) (menu-bar-lines . 0)))
address@hidden example
+
address@hidden
+specifies to display a buffer named @samp{myfile} in a dedicated frame
+with specified @code{minibuffer} and @code{menu-bar-lines} parameters.
+
+The list of frame parameters can also use the phony frame parameters
address@hidden and @code{same-window}.  If the specified frame
+parameters include @code{(same-window . @var{value})} and @var{value}
+is address@hidden, that means to display the buffer in the current
+selected window.  Otherwise, if they include @code{(same-frame .
address@hidden)} and @var{value} is address@hidden, that means to display
+the buffer in a new window in the currently selected frame.
address@hidden defopt
+
address@hidden special-display-regexps
+A list of regular expressions that specify buffers that should be
+displayed specially.  If the buffer's name matches any of the regular
+expressions in this list, @code{display-buffer} handles the buffer
+specially.
+
+By default, special display means to give the buffer a dedicated frame.
+
+If an element is a list, instead of a string, then the @sc{car} of the
+list is the regular expression, and the rest of the list says how to
+create the frame.  See above, under @code{special-display-buffer-names}.
address@hidden defopt
+
address@hidden special-display-p buffer-name
+This function returns address@hidden if displaying a buffer
+named @var{buffer-name} with @code{display-buffer} would
+create a special frame.  The value is @code{t} if it would
+use the default frame parameters, or else the specified list
+of frame parameters.
address@hidden defun
+
address@hidden special-display-function
+This variable holds the function to call to display a buffer specially.
+It receives the buffer as an argument, and should return the window in
+which it is displayed.
+
+The default value of this variable is
address@hidden
address@hidden defvar
+
address@hidden special-display-popup-frame buffer &optional args
+This function makes @var{buffer} visible in a frame of its own.  If
address@hidden is already displayed in a window in some frame, it makes
+the frame visible and raises it, to use that window.  Otherwise, it
+creates a frame that will be dedicated to @var{buffer}.  This
+function returns the window it used.
+
+If @var{args} is an alist, it specifies frame parameters for the new
+frame.
+
+If @var{args} is a list whose @sc{car} is a symbol, then @code{(car
address@hidden)} is called as a function to actually create and set up the
+frame; it is called with @var{buffer} as first argument, and @code{(cdr
address@hidden)} as additional arguments.
+
+This function always uses an existing window displaying @var{buffer},
+whether or not it is in a frame of its own; but if you set up the above
+variables in your init file, before @var{buffer} was created, then
+presumably the window was previously made by this function.
address@hidden defun
+
address@hidden special-display-frame-alist
address@hidden of special-display-frame-alist}
+This variable holds frame parameters for
address@hidden to use when it creates a frame.
address@hidden defopt
+
address@hidden same-window-buffer-names
+A list of buffer names for buffers that should be displayed in the
+selected window.  If the buffer's name is in this list,
address@hidden handles the buffer by switching to it in the
+selected window.
address@hidden defopt
+
address@hidden same-window-regexps
+A list of regular expressions that specify buffers that should be
+displayed in the selected window.  If the buffer's name matches any of
+the regular expressions in this list, @code{display-buffer} handles the
+buffer by switching to it in the selected window.
address@hidden defopt
+
address@hidden same-window-p buffer-name
+This function returns @code{t} if displaying a buffer
+named @var{buffer-name} with @code{display-buffer} would
+put it in the selected window.
address@hidden defun
+
address@hidden Emacs 19 feature
address@hidden display-buffer-function
+This variable is the most flexible way to customize the behavior of
address@hidden  If it is address@hidden, it should be a function
+that @code{display-buffer} calls to do the work.  The function should
+accept two arguments, the first two arguments that @code{display-buffer}
+received.  It should choose or create a window, display the specified
+buffer in it, and then return the window.
+
+This hook takes precedence over all the other options and hooks
+described above.
address@hidden defvar
+
address@hidden Emacs 19 feature
address@hidden dedicated window
+A window can be marked as ``dedicated'' to its buffer.  Then
address@hidden will not try to use that window to display any
+other buffer.
+
address@hidden window-dedicated-p window
+This function returns address@hidden if @var{window} is marked as
+dedicated; otherwise @code{nil}.
address@hidden defun
+
address@hidden set-window-dedicated-p window flag
+This function marks @var{window} as dedicated if @var{flag} is
address@hidden, and nondedicated otherwise.
address@hidden defun
+
address@hidden Window Point
address@hidden Windows and Point
address@hidden window position
address@hidden window point
address@hidden position in window
address@hidden point in window
+
+  Each window has its own value of point, independent of the value of
+point in other windows displaying the same buffer.  This makes it useful
+to have multiple windows showing one buffer.
+
address@hidden @bullet
address@hidden
+The window point is established when a window is first created; it is
+initialized from the buffer's point, or from the window point of another
+window opened on the buffer if such a window exists.
+
address@hidden
+Selecting a window sets the value of point in its buffer from the
+window's value of point.  Conversely, deselecting a window sets the
+window's value of point from that of the buffer.  Thus, when you switch
+between windows that display a given buffer, the point value for the
+selected window is in effect in the buffer, while the point values for
+the other windows are stored in those windows.
+
address@hidden
+As long as the selected window displays the current buffer, the window's
+point and the buffer's point always move together; they remain equal.
address@hidden itemize
+
address@hidden
address@hidden, for more details on buffer positions.
+
address@hidden cursor
+  As far as the user is concerned, point is where the cursor is, and
+when the user switches to another buffer, the cursor jumps to the
+position of point in that buffer.
+
address@hidden window-point &optional window
+This function returns the current position of point in @var{window}.
+For a nonselected window, this is the value point would have (in that
+window's buffer) if that window were selected.  If @var{window} is
address@hidden, the selected window is used.
+
+When @var{window} is the selected window and its buffer is also the
+current buffer, the value returned is the same as point in that buffer.
+
+Strictly speaking, it would be more correct to return the
+``top-level'' value of point, outside of any @code{save-excursion}
+forms.  But that value is hard to find.
address@hidden defun
+
address@hidden set-window-point window position
+This function positions point in @var{window} at position
address@hidden in @var{window}'s buffer.  It returns @var{position}.
+
+If @var{window} is selected, and its buffer is current,
+this simply does @code{goto-char}.
address@hidden defun
+
address@hidden Window Start
address@hidden The Window Start Position
address@hidden window start position
+
+  Each window contains a marker used to keep track of a buffer position
+that specifies where in the buffer display should start.  This position
+is called the @dfn{display-start} position of the window (or just the
address@hidden).  The character after this position is the one that appears
+at the upper left corner of the window.  It is usually, but not
+inevitably, at the beginning of a text line.
+
address@hidden window-start &optional window
address@hidden window top line
+This function returns the display-start position of window
address@hidden  If @var{window} is @code{nil}, the selected window is
+used.  For example,
+
address@hidden
address@hidden
+(window-start)
+     @result{} 7058
address@hidden group
address@hidden example
+
+When you create a window, or display a different buffer in it, the
+display-start position is set to a display-start position recently used
+for the same buffer, or 1 if the buffer doesn't have any.
+
+Redisplay updates the window-start position (if you have not specified
+it explicitly since the previous redisplay)---for example, to make sure
+point appears on the screen.  Nothing except redisplay automatically
+changes the window-start position; if you move point, do not expect the
+window-start position to change in response until after the next
+redisplay.
+
+For a realistic example of using @code{window-start}, see the
+description of @code{count-lines}.  @xref{Definition of count-lines}.
address@hidden defun
+
address@hidden window-end &optional window update
+This function returns the position of the end of the display in window
address@hidden  If @var{window} is @code{nil}, the selected window is
+used.
+
+Simply changing the buffer text or moving point does not update the
+value that @code{window-end} returns.  The value is updated only when
+Emacs redisplays and redisplay completes without being preempted.
+
+If the last redisplay of @var{window} was preempted, and did not finish,
+Emacs does not know the position of the end of display in that window.
+In that case, this function returns @code{nil}.
+
+If @var{update} is address@hidden, @code{window-end} always returns an
+up-to-date value for where the window ends, based on the current
address@hidden value.  If the saved value is valid,
address@hidden returns that; otherwise it computes the correct
+value by scanning the buffer text.
+
+Even if @var{update} is address@hidden, @code{window-end} does not
+attempt to scroll the display if point has moved off the screen, the
+way real redisplay would do.  It does not alter the
address@hidden value.  In effect, it reports where the displayed
+text will end if scrolling is not required.
address@hidden defun
+
address@hidden set-window-start window position &optional noforce
+This function sets the display-start position of @var{window} to
address@hidden in @var{window}'s buffer.  It returns @var{position}.
+
+The display routines insist that the position of point be visible when a
+buffer is displayed.  Normally, they change the display-start position
+(that is, scroll the window) whenever necessary to make point visible.
+However, if you specify the start position with this function using
address@hidden for @var{noforce}, it means you want display to start at
address@hidden even if that would put the location of point off the
+screen.  If this does place point off screen, the display routines move
+point to the left margin on the middle line in the window.
+
+For example, if point @w{is 1} and you set the start of the window @w{to
+2}, then point would be ``above'' the top of the window.  The display
+routines will automatically move point if it is still 1 when redisplay
+occurs.  Here is an example:
+
address@hidden
address@hidden
+;; @r{Here is what @samp{foo} looks like before executing}
+;;   @r{the @code{set-window-start} expression.}
address@hidden group
+
address@hidden
+---------- Buffer: foo ----------
address@hidden is the contents of buffer foo.
+2
+3
+4
+5
+6
+---------- Buffer: foo ----------
address@hidden group
+
address@hidden
+(set-window-start
+ (selected-window)
+ (1+ (window-start)))
address@hidden 2
address@hidden group
+
address@hidden
+;; @r{Here is what @samp{foo} looks like after executing}
+;;   @r{the @code{set-window-start} expression.}
+---------- Buffer: foo ----------
+his is the contents of buffer foo.
+2
+3
address@hidden
+5
+6
+---------- Buffer: foo ----------
address@hidden group
address@hidden example
+
+If @var{noforce} is address@hidden, and @var{position} would place point
+off screen at the next redisplay, then redisplay computes a new window-start
+position that works well with point, and thus @var{position} is not used.
address@hidden defun
+
address@hidden pos-visible-in-window-p &optional position window partially
+This function returns address@hidden if @var{position} is within the
+range of text currently visible on the screen in @var{window}.  It
+returns @code{nil} if @var{position} is scrolled vertically out of
+view.  Locations that are partially obscured are not considered
+visible unless @var{partially} is address@hidden  The argument
address@hidden defaults to the current position of point in
address@hidden; @var{window}, to the selected window.
+
+If @var{position} is @code{t}, that means to check the last visible
+position in @var{window}.
+
+The @code{pos-visible-in-window-p} function considers only vertical
+scrolling.  If @var{position} is out of view only because @var{window}
+has been scrolled horizontally, @code{pos-visible-in-window-p} returns
address@hidden anyway.  @xref{Horizontal Scrolling}.
+
+If @var{position} is visible, @code{pos-visible-in-window-p} returns
address@hidden if @var{partially} is @code{nil}; if @var{partially} is
address@hidden, and the character after @var{position} is fully
+visible, it returns a list of the form @code{(@var{x} @var{y})}, where
address@hidden and @var{y} are the pixel coordinates relative to the top left
+corner of the window; otherwise it returns an extended list of the
+form @code{(@var{x} @var{y} @var{rtop} @var{rbot} @var{rowh}
address@hidden)}, where the @var{rtop} and @var{rbot} specify the number
+of off-window pixels at the top and bottom of the row at
address@hidden, @var{rowh} specifies the visible height of that row,
+and @var{vpos} specifies the vertical position (zero-based row number)
+of that row.
+
+Here is an example:
+
address@hidden
address@hidden
+;; @r{If point is off the screen now, recenter it now.}
+(or (pos-visible-in-window-p
+     (point) (selected-window))
+    (recenter 0))
address@hidden group
address@hidden example
address@hidden defun
+
address@hidden window-line-height &optional line window
+This function returns information about text line @var{line} in @var{window}.
+If @var{line} is one of @code{header-line} or @code{mode-line},
address@hidden returns information about the corresponding
+line of the window.  Otherwise, @var{line} is a text line number
+starting from 0.  A negative number counts from the end of the window.
+The argument @var{line} defaults to the current line in @var{window};
address@hidden, to the selected window.
+
+If the display is not up to date, @code{window-line-height} returns
address@hidden  In that case, @code{pos-visible-in-window-p} may be used
+to obtain related information.
+
+If there is no line corresponding to the specified @var{line},
address@hidden returns @code{nil}.  Otherwise, it returns
+a list @code{(@var{height} @var{vpos} @var{ypos} @var{offbot})},
+where @var{height} is the height in pixels of the visible part of the
+line, @var{vpos} and @var{ypos} are the vertical position in lines and
+pixels of the line relative to the top of the first text line, and
address@hidden is the number of off-window pixels at the bottom of the
+text line.  If there are off-window pixels at the top of the (first)
+text line, @var{ypos} is negative.
address@hidden defun
+
address@hidden Textual Scrolling
address@hidden Textual Scrolling
address@hidden textual scrolling
address@hidden scrolling textually
+
+  @dfn{Textual scrolling} means moving the text up or down through a
+window.  It works by changing the value of the window's display-start
+location.  It may also change the value of @code{window-point} to keep
+point on the screen.
+
+  Textual scrolling was formerly called ``vertical scrolling,'' but we
+changed its name to distinguish it from the new vertical fractional
+scrolling feature (@pxref{Vertical Scrolling}).
+
+  In the commands @code{scroll-up} and @code{scroll-down}, the directions
+``up'' and ``down'' refer to the motion of the text in the buffer at which
+you are looking through the window.  Imagine that the text is
+written on a long roll of paper and that the scrolling commands move the
+paper up and down.  Thus, if you are looking at text in the middle of a
+buffer and repeatedly call @code{scroll-down}, you will eventually see
+the beginning of the buffer.
+
+  Some people have urged that the opposite convention be used: they
+imagine that the window moves over text that remains in place.  Then
+``down'' commands would take you to the end of the buffer.  This view is
+more consistent with the actual relationship between windows and the
+text in the buffer, but it is less like what the user sees.  The
+position of a window on the terminal does not move, and short scrolling
+commands clearly move the text up or down on the screen.  We have chosen
+names that fit the user's point of view.
+
+  The textual scrolling functions (aside from
address@hidden) have unpredictable results if the current
+buffer is different from the buffer that is displayed in the selected
+window.  @xref{Current Buffer}.
+
+  If the window contains a row which is taller than the height of the
+window (for example in the presence of a large image), the scroll
+functions will adjust the window vscroll to scroll the partially
+visible row.  To disable this feature, Lisp code may bind the variable
+`auto-window-vscroll' to @code{nil} (@pxref{Vertical Scrolling}).
+
address@hidden Command scroll-up &optional count
+This function scrolls the text in the selected window upward
address@hidden lines.  If @var{count} is negative, scrolling is actually
+downward.
+
+If @var{count} is @code{nil} (or omitted), then the length of scroll
+is @code{next-screen-context-lines} lines less than the usable height of
+the window (not counting its mode line).
+
address@hidden returns @code{nil}, unless it gets an error
+because it can't scroll any further.
address@hidden deffn
+
address@hidden Command scroll-down &optional count
+This function scrolls the text in the selected window downward
address@hidden lines.  If @var{count} is negative, scrolling is actually
+upward.
+
+If @var{count} is omitted or @code{nil}, then the length of the scroll
+is @code{next-screen-context-lines} lines less than the usable height of
+the window (not counting its mode line).
+
address@hidden returns @code{nil}, unless it gets an error because
+it can't scroll any further.
address@hidden deffn
+
address@hidden Command scroll-other-window &optional count
+This function scrolls the text in another window upward @var{count}
+lines.  Negative values of @var{count}, or @code{nil}, are handled
+as in @code{scroll-up}.
+
+You can specify which buffer to scroll by setting the variable
address@hidden to a buffer.  If that buffer isn't
+already displayed, @code{scroll-other-window} displays it in some
+window.
+
+When the selected window is the minibuffer, the next window is normally
+the one at the top left corner.  You can specify a different window to
+scroll, when the minibuffer is selected, by setting the variable
address@hidden  This variable has no effect when any
+other window is selected.  When it is address@hidden and the
+minibuffer is selected, it takes precedence over
address@hidden  @xref{Definition of
+minibuffer-scroll-window}.
+
+When the minibuffer is active, it is the next window if the selected
+window is the one at the bottom right corner.  In this case,
address@hidden attempts to scroll the minibuffer.  If the
+minibuffer contains just one line, it has nowhere to scroll to, so the
+line reappears after the echo area momentarily displays the message
address@hidden of buffer}.
address@hidden deffn
+
address@hidden Emacs 19 feature
address@hidden other-window-scroll-buffer
+If this variable is address@hidden, it tells @code{scroll-other-window}
+which buffer to scroll.
address@hidden defvar
+
address@hidden scroll-margin
+This option specifies the size of the scroll margin---a minimum number
+of lines between point and the top or bottom of a window.  Whenever
+point gets within this many lines of the top or bottom of the window,
+redisplay scrolls the text automatically (if possible) to move point
+out of the margin, closer to the center of the window.
address@hidden defopt
+
address@hidden scroll-conservatively
+This variable controls how scrolling is done automatically when point
+moves off the screen (or into the scroll margin).  If the value is a
+positive integer @var{n}, then redisplay scrolls the text up to
address@hidden lines in either direction, if that will bring point back into
+proper view.  This action is called @dfn{conservative scrolling}.
+Otherwise, scrolling happens in the usual way, under the control of
+other variables such as @code{scroll-up-aggressively} and
address@hidden
+
+The default value is zero, which means that conservative scrolling
+never happens.
address@hidden defopt
+
address@hidden scroll-down-aggressively
+The value of this variable should be either @code{nil} or a fraction
address@hidden between 0 and 1.  If it is a fraction, that specifies where on
+the screen to put point when scrolling down.  More precisely, when a
+window scrolls down because point is above the window start, the new
+start position is chosen to put point @var{f} part of the window
+height from the top.  The larger @var{f}, the more aggressive the
+scrolling.
+
+A value of @code{nil} is equivalent to .5, since its effect is to center
+point.  This variable automatically becomes buffer-local when set in any
+fashion.
address@hidden defopt
+
address@hidden scroll-up-aggressively
+Likewise, for scrolling up.  The value, @var{f}, specifies how far
+point should be placed from the bottom of the window; thus, as with
address@hidden, a larger value scrolls more aggressively.
address@hidden defopt
+
address@hidden scroll-step
+This variable is an older variant of @code{scroll-conservatively}.  The
+difference is that it if its value is @var{n}, that permits scrolling
+only by precisely @var{n} lines, not a smaller number.  This feature
+does not work with @code{scroll-margin}.  The default value is zero.
address@hidden defopt
+
address@hidden scroll-preserve-screen-position
+If this option is @code{t}, scrolling which would move the current
+point position out of the window chooses the new position of point
+so that the vertical position of the cursor is unchanged, if possible.
+
+If it is address@hidden and not @code{t}, then the scrolling functions
+always preserve the vertical position of point, if possible.
address@hidden defopt
+
address@hidden next-screen-context-lines
+The value of this variable is the number of lines of continuity to
+retain when scrolling by full screens.  For example, @code{scroll-up}
+with an argument of @code{nil} scrolls so that this many lines at the
+bottom of the window appear instead at the top.  The default value is
address@hidden
address@hidden defopt
+
address@hidden Command recenter &optional count
address@hidden centering point
+This function scrolls the text in the selected window so that point is
+displayed at a specified vertical position within the window.  It does
+not ``move point'' with respect to the text.
+
+If @var{count} is a nonnegative number, that puts the line containing
+point @var{count} lines down from the top of the window.  If
address@hidden is a negative number, then it counts upward from the
+bottom of the window, so that @minus{}1 stands for the last usable
+line in the window.  If @var{count} is a address@hidden list, then it
+stands for the line in the middle of the window.
+
+If @var{count} is @code{nil}, @code{recenter} puts the line containing
+point in the middle of the window, then clears and redisplays the entire
+selected frame.
+
+When @code{recenter} is called interactively, @var{count} is the raw
+prefix argument.  Thus, typing @kbd{C-u} as the prefix sets the
address@hidden to a address@hidden list, while typing @kbd{C-u 4} sets
address@hidden to 4, which positions the current line four lines from the
+top.
+
+With an argument of zero, @code{recenter} positions the current line at
+the top of the window.  This action is so handy that some people make a
+separate key binding to do this.  For example,
+
address@hidden
address@hidden
+(defun line-to-top-of-window ()
+  "Scroll current line to top of window.
+Replaces three keystroke sequence C-u 0 C-l."
+  (interactive)
+  (recenter 0))
+
+(global-set-key [kp-multiply] 'line-to-top-of-window)
address@hidden group
address@hidden example
address@hidden deffn
+
address@hidden Vertical Scrolling
address@hidden Vertical Fractional Scrolling
address@hidden vertical fractional scrolling
+
+  @dfn{Vertical fractional scrolling} means shifting the image in the
+window up or down by a specified multiple or fraction of a line.
+Each window has a @dfn{vertical scroll position},
+which is a number, never less than zero.  It specifies how far to raise
+the contents of the window.  Raising the window contents generally makes
+all or part of some lines disappear off the top, and all or part of some
+other lines appear at the bottom.  The usual value is zero.
+
+  The vertical scroll position is measured in units of the normal line
+height, which is the height of the default font.  Thus, if the value is
+.5, that means the window contents are scrolled up half the normal line
+height.  If it is 3.3, that means the window contents are scrolled up
+somewhat over three times the normal line height.
+
+  What fraction of a line the vertical scrolling covers, or how many
+lines, depends on what the lines contain.  A value of .5 could scroll a
+line whose height is very short off the screen, while a value of 3.3
+could scroll just part of the way through a tall line or an image.
+
address@hidden window-vscroll &optional window pixels-p
+This function returns the current vertical scroll position of
address@hidden  If @var{window} is @code{nil}, the selected window is
+used.  If @var{pixels-p} is address@hidden, the return value is
+measured in pixels, rather than in units of the normal line height.
+
address@hidden
address@hidden
+(window-vscroll)
+     @result{} 0
address@hidden group
address@hidden example
address@hidden defun
+
address@hidden set-window-vscroll window lines &optional pixels-p
+This function sets @var{window}'s vertical scroll position to
address@hidden  The argument @var{lines} should be zero or positive; if
+not, it is taken as zero.
+
+If @var{window} is @code{nil}, the selected window is used.
+
+The actual vertical scroll position must always correspond
+to an integral number of pixels, so the value you specify
+is rounded accordingly.
+
+The return value is the result of this rounding.
+
address@hidden
address@hidden
+(set-window-vscroll (selected-window) 1.2)
+     @result{} 1.13
address@hidden group
address@hidden example
+
+If @var{pixels-p} is address@hidden, @var{lines} specifies a number of
+pixels.  In this case, the return value is @var{lines}.
address@hidden defun
+
address@hidden auto-window-vscroll
+If this variable is address@hidden, the line-move, scroll-up, and
+scroll-down functions will automatically modify the window vscroll to
+scroll through display rows that are taller that the height of the
+window, for example in the presence of large images.
address@hidden defvar
+
address@hidden Horizontal Scrolling
address@hidden Horizontal Scrolling
address@hidden horizontal scrolling
+
+  @dfn{Horizontal scrolling} means shifting the image in the window left
+or right by a specified multiple of the normal character width.  Each
+window has a @dfn{horizontal scroll position}, which is a number, never
+less than zero.  It specifies how far to shift the contents left.
+Shifting the window contents left generally makes all or part of some
+characters disappear off the left, and all or part of some other
+characters appear at the right.  The usual value is zero.
+
+  The horizontal scroll position is measured in units of the normal
+character width, which is the width of space in the default font.  Thus,
+if the value is 5, that means the window contents are scrolled left by 5
+times the normal character width.  How many characters actually
+disappear off to the left depends on their width, and could vary from
+line to line.
+
+  Because we read from side to side in the ``inner loop,'' and from top
+to bottom in the ``outer loop,'' the effect of horizontal scrolling is
+not like that of textual or vertical scrolling.  Textual scrolling
+involves selection of a portion of text to display, and vertical
+scrolling moves the window contents contiguously; but horizontal
+scrolling causes part of @emph{each line} to go off screen.
+
+  Usually, no horizontal scrolling is in effect; then the leftmost
+column is at the left edge of the window.  In this state, scrolling to
+the right is meaningless, since there is no data to the left of the edge
+to be revealed by it; so this is not allowed.  Scrolling to the left is
+allowed; it scrolls the first columns of text off the edge of the window
+and can reveal additional columns on the right that were truncated
+before.  Once a window has a nonzero amount of leftward horizontal
+scrolling, you can scroll it back to the right, but only so far as to
+reduce the net horizontal scroll to zero.  There is no limit to how far
+left you can scroll, but eventually all the text will disappear off the
+left edge.
+
address@hidden auto-hscroll-mode
+  If @code{auto-hscroll-mode} is set, redisplay automatically alters
+the horizontal scrolling of a window as necessary to ensure that point
+is always visible.  However, you can still set the horizontal
+scrolling value explicitly.  The value you specify serves as a lower
+bound for automatic scrolling, i.e. automatic scrolling will not
+scroll a window to a column less than the specified one.
+
address@hidden Command scroll-left &optional count set-minimum
+This function scrolls the selected window @var{count} columns to the
+left (or to the right if @var{count} is negative).  The default
+for @var{count} is the window width, minus 2.
+
+The return value is the total amount of leftward horizontal scrolling in
+effect after the change---just like the value returned by
address@hidden (below).
+
+Once you scroll a window as far right as it can go, back to its normal
+position where the total leftward scrolling is zero, attempts to scroll
+any farther right have no effect.
+
+If @var{set-minimum} is address@hidden, the new scroll amount becomes
+the lower bound for automatic scrolling; that is, automatic scrolling
+will not scroll a window to a column less than the value returned by
+this function.  Interactive calls pass address@hidden for
address@hidden
address@hidden deffn
+
address@hidden Command scroll-right &optional count set-minimum
+This function scrolls the selected window @var{count} columns to the
+right (or to the left if @var{count} is negative).  The default
+for @var{count} is the window width, minus 2.  Aside from the direction
+of scrolling, this works just like @code{scroll-left}.
address@hidden deffn
+
address@hidden window-hscroll &optional window
+This function returns the total leftward horizontal scrolling of
address@hidden number of columns by which the text in @var{window}
+is scrolled left past the left margin.
+
+The value is never negative.  It is zero when no horizontal scrolling
+has been done in @var{window} (which is usually the case).
+
+If @var{window} is @code{nil}, the selected window is used.
+
address@hidden
address@hidden
+(window-hscroll)
+     @result{} 0
address@hidden group
address@hidden
+(scroll-left 5)
+     @result{} 5
address@hidden group
address@hidden
+(window-hscroll)
+     @result{} 5
address@hidden group
address@hidden example
address@hidden defun
+
address@hidden set-window-hscroll window columns
+This function sets horizontal scrolling of @var{window}.  The value of
address@hidden specifies the amount of scrolling, in terms of columns
+from the left margin.  The argument @var{columns} should be zero or
+positive; if not, it is taken as zero.  Fractional values of
address@hidden are not supported at present.
+
+Note that @code{set-window-hscroll} may appear not to work if you test
+it by evaluating a call with @kbd{M-:} in a simple way.  What happens
+is that the function sets the horizontal scroll value and returns, but
+then redisplay adjusts the horizontal scrolling to make point visible,
+and this overrides what the function did.  You can observe the
+function's effect if you call it while point is sufficiently far from
+the left margin that it will remain visible.
+
+The value returned is @var{columns}.
+
address@hidden
address@hidden
+(set-window-hscroll (selected-window) 10)
+     @result{} 10
address@hidden group
address@hidden example
address@hidden defun
+
+  Here is how you can determine whether a given position @var{position}
+is off the screen due to horizontal scrolling:
+
address@hidden
address@hidden
+(defun hscroll-on-screen (window position)
+  (save-excursion
+    (goto-char position)
+    (and
+     (>= (- (current-column) (window-hscroll window)) 0)
+     (< (- (current-column) (window-hscroll window))
+        (window-width window)))))
address@hidden group
address@hidden example
+
address@hidden Size of Window
address@hidden The Size of a Window
address@hidden window size
address@hidden size of window
+
+  An Emacs window is rectangular, and its size information consists of
+the height (the number of lines) and the width (the number of character
+positions in each line).  The mode line is included in the height.  But
+the width does not count the scroll bar or the column of @samp{|}
+characters that separates side-by-side windows.
+
+  The following three functions return size information about a window:
+
address@hidden window-height &optional window
+This function returns the number of lines in @var{window}, including
+its mode line and header line, if any.  If @var{window} fills its
+entire frame except for the echo area, this is typically one less than
+the value of @code{frame-height} on that frame.
+
+If @var{window} is @code{nil}, the function uses the selected window.
+
address@hidden
address@hidden
+(window-height)
+     @result{} 23
address@hidden group
address@hidden
+(split-window-vertically)
+     @result{} #<window 4 on windows.texi>
address@hidden group
address@hidden
+(window-height)
+     @result{} 11
address@hidden group
address@hidden example
address@hidden defun
+
address@hidden window-body-height &optional window
+Like @code{window-height} but the value does not include the
+mode line (if any) or the header line (if any).
address@hidden defun
+
address@hidden window-width &optional window
+This function returns the number of columns in @var{window}.  If
address@hidden fills its entire frame, this is the same as the value of
address@hidden on that frame.  The width does not include the
+window's scroll bar or the column of @samp{|} characters that separates
+side-by-side windows.
+
+If @var{window} is @code{nil}, the function uses the selected window.
+
address@hidden
address@hidden
+(window-width)
+     @result{} 80
address@hidden group
address@hidden example
address@hidden defun
+
address@hidden window-full-width-p &optional window
+This function returns address@hidden if @var{window} is as wide as
+the frame that contains it; otherwise @code{nil}.
+If @var{window} is @code{nil}, the function uses the selected window.
address@hidden defun
+
address@hidden window-edges &optional window
+This function returns a list of the edge coordinates of @var{window}.
+If @var{window} is @code{nil}, the selected window is used.
+
+The order of the list is @code{(@var{left} @var{top} @var{right}
address@hidden)}, all elements relative to 0, 0 at the top left corner of
+the frame.  The element @var{right} of the value is one more than the
+rightmost column used by @var{window}, and @var{bottom} is one more than
+the bottommost row used by @var{window} and its mode-line.
+
+The edges include the space used by the window's scroll bar, display
+margins, fringes, header line, and mode line, if it has them.  Also,
+if the window has a neighbor on the right, its right edge value
+includes the width of the separator line between the window and that
+neighbor.  Since the width of the window does not include this
+separator, the width does not usually equal the difference between the
+right and left edges.
address@hidden defun
+
address@hidden window-inside-edges &optional window
+This is similar to @code{window-edges}, but the edge values
+it returns include only the text area of the window.  They
+do not include the header line, mode line, scroll bar or
+vertical separator, fringes, or display margins.
address@hidden defun
+
+Here are the results obtained on a typical 24-line terminal with just
+one window, with menu bar enabled:
+
address@hidden
address@hidden
+(window-edges (selected-window))
+     @result{} (0 1 80 23)
address@hidden group
address@hidden
+(window-inside-edges (selected-window))
+     @result{} (0 1 80 22)
address@hidden group
address@hidden example
+
address@hidden
+The bottom edge is at line 23 because the last line is the echo area.
+The bottom inside edge is at line 22, which is the window's mode line.
+
+If @var{window} is at the upper left corner of its frame, and there is
+no menu bar, then @var{bottom} returned by @code{window-edges} is the
+same as the value of @code{(window-height)}, @var{right} is almost the
+same as the value of @code{(window-width)}, and @var{top} and
address@hidden are zero.  For example, the edges of the following window
+are @address@hidden 0 8 5}}.  Assuming that the frame has more than 8
+columns, the last column of the window (column 7) holds a border
+rather than text.  The last row (row 4) holds the mode line, shown
+here with @samp{xxxxxxxxx}.
+
address@hidden
address@hidden
+           0
+           _______
+        0 |       |
+          |       |
+          |       |
+          |       |
+          xxxxxxxxx  4
+
+                  7
address@hidden group
address@hidden example
+
+In the following example, let's suppose that the frame is 7
+columns wide.  Then the edges of the left window are @address@hidden 0 4 3}}
+and the edges of the right window are @address@hidden 0 7 3}}.
+The inside edges of the left window are @address@hidden 0 3 2}},
+and the inside edges of the right window are @address@hidden 0 7 2}},
+
address@hidden
address@hidden
+           ___ ___
+          |   |   |
+          |   |   |
+          xxxxxxxxx
+
+           0  34  7
address@hidden group
address@hidden example
+
address@hidden window-pixel-edges &optional window
+This function is like @code{window-edges} except that, on a graphical
+display, the edge values are measured in pixels instead of in
+character lines and columns.
address@hidden defun
+
address@hidden window-inside-pixel-edges &optional window
+This function is like @code{window-inside-edges} except that, on a
+graphical display, the edge values are measured in pixels instead of
+in character lines and columns.
address@hidden defun
+
address@hidden Resizing Windows
address@hidden Changing the Size of a Window
address@hidden window resizing
address@hidden resize window
address@hidden changing window size
address@hidden window size, changing
+
+  The window size functions fall into two classes: high-level commands
+that change the size of windows and low-level functions that access
+window size.  Emacs does not permit overlapping windows or gaps between
+windows, so resizing one window affects other windows.
+
address@hidden Command enlarge-window size &optional horizontal
+This function makes the selected window @var{size} lines taller,
+stealing lines from neighboring windows.  It takes the lines from one
+window at a time until that window is used up, then takes from another.
+If a window from which lines are stolen shrinks below
address@hidden lines, that window disappears.
+
+If @var{horizontal} is address@hidden, this function makes
address@hidden wider by @var{size} columns, stealing columns instead of
+lines.  If a window from which columns are stolen shrinks below
address@hidden columns, that window disappears.
+
+If the requested size would exceed that of the window's frame, then the
+function makes the window occupy the entire height (or width) of the
+frame.
+
+If there are various other windows from which lines or columns can be
+stolen, and some of them specify fixed size (using
address@hidden, see below), they are left untouched while
+other windows are ``robbed.''  If it would be necessary to alter the
+size of a fixed-size window, @code{enlarge-window} gets an error
+instead.
+
+If @var{size} is negative, this function shrinks the window by
address@hidden@var{size} lines or columns.  If that makes the window smaller
+than the minimum size (@code{window-min-height} and
address@hidden), @code{enlarge-window} deletes the window.
+
address@hidden returns @code{nil}.
address@hidden deffn
+
address@hidden Command enlarge-window-horizontally columns
+This function makes the selected window @var{columns} wider.
+It could be defined as follows:
+
address@hidden
address@hidden
+(defun enlarge-window-horizontally (columns)
+  (interactive "p")
+  (enlarge-window columns t))
address@hidden group
address@hidden example
address@hidden deffn
+
address@hidden Command shrink-window size &optional horizontal
+This function is like @code{enlarge-window} but negates the argument
address@hidden, making the selected window smaller by giving lines (or
+columns) to the other windows.  If the window shrinks below
address@hidden or @code{window-min-width}, then it disappears.
+
+If @var{size} is negative, the window is enlarged by @address@hidden
+lines or columns.
address@hidden deffn
+
address@hidden Command shrink-window-horizontally columns
+This function makes the selected window @var{columns} narrower.
+It could be defined as follows:
+
address@hidden
address@hidden
+(defun shrink-window-horizontally (columns)
+  (interactive "p")
+  (shrink-window columns t))
address@hidden group
address@hidden example
address@hidden deffn
+
address@hidden adjust-window-trailing-edge window delta horizontal
+This function makes the selected window @var{delta} lines taller or
address@hidden columns wider, by moving the bottom or right edge.  This
+function does not delete other windows; if it cannot make the
+requested size adjustment, it signals an error.  On success, this
+function returns @code{nil}.
address@hidden defun
+
address@hidden fit-window-to-buffer &optional window max-height min-height
+This function makes @var{window} the right height to display its
+contents exactly.  If @var{window} is omitted or @code{nil}, it uses
+the selected window.
+
+The argument @var{max-height} specifies the maximum height the window
+is allowed to be; @code{nil} means use the frame height.  The argument
address@hidden specifies the minimum height for the window;
address@hidden means use @code{window-min-height}.  All these height
+values include the mode-line and/or header-line.
address@hidden defun
+
address@hidden Command shrink-window-if-larger-than-buffer &optional window
+This command shrinks @var{window} vertically to be as small as
+possible while still showing the full contents of its buffer---but not
+less than @code{window-min-height} lines.  If @var{window} is not
+given, it defaults to the selected window.
+
+However, the command does nothing if the window is already too small to
+display the whole text of the buffer, or if part of the contents are
+currently scrolled off screen, or if the window is not the full width of
+its frame, or if the window is the only window in its frame.
+
+This command returns address@hidden if it actually shrank the window
+and @code{nil} otherwise.
address@hidden deffn
+
address@hidden window-size-fixed
+If this variable is address@hidden, in any given buffer,
+then the size of any window displaying the buffer remains fixed
+unless you explicitly change it or Emacs has no other choice.
+
+If the value is @code{height}, then only the window's height is fixed;
+if the value is @code{width}, then only the window's width is fixed.
+Any other address@hidden value fixes both the width and the height.
+
+This variable automatically becomes buffer-local when set.
+
+Explicit size-change functions such as @code{enlarge-window}
+get an error if they would have to change a window size which is fixed.
+Therefore, when you want to change the size of such a window,
+you should bind @code{window-size-fixed} to @code{nil}, like this:
+
address@hidden
+(let ((window-size-fixed nil))
+   (enlarge-window 10))
address@hidden example
+
+Note that changing the frame size will change the size of a
+fixed-size window, if there is no other alternative.
address@hidden defvar
+
address@hidden minimum window size
+  The following two variables constrain the window-structure-changing
+functions to a minimum height and width.
+
address@hidden window-min-height
+The value of this variable determines how short a window may become
+before it is automatically deleted.  Making a window smaller than
address@hidden automatically deletes it, and no window may
+be created shorter than this.  The default value is 4.
+
+The absolute minimum window height is one; actions that change window
+sizes reset this variable to one if it is less than one.
address@hidden defopt
+
address@hidden window-min-width
+The value of this variable determines how narrow a window may become
+before it is automatically deleted.  Making a window smaller than
address@hidden automatically deletes it, and no window may be
+created narrower than this.  The default value is 10.
+
+The absolute minimum window width is two; actions that change window
+sizes reset this variable to two if it is less than two.
address@hidden defopt
+
address@hidden Coordinates and Windows
address@hidden Coordinates and Windows
+
+This section describes how to relate screen coordinates to windows.
+
address@hidden window-at x y &optional frame
+This function returns the window containing the specified cursor
+position in the frame @var{frame}.  The coordinates @var{x} and @var{y}
+are measured in characters and count from the top left corner of the
+frame.  If they are out of range, @code{window-at} returns @code{nil}.
+
+If you omit @var{frame}, the selected frame is used.
address@hidden defun
+
address@hidden coordinates-in-window-p coordinates window
+This function checks whether a particular frame position falls within
+the window @var{window}.
+
+The argument @var{coordinates} is a cons cell of the form @code{(@var{x}
+. @var{y})}.  The coordinates @var{x} and @var{y} are measured in
+characters, and count from the top left corner of the screen or frame.
+
+The value returned by @code{coordinates-in-window-p} is address@hidden
+if the coordinates are inside @var{window}.  The value also indicates
+what part of the window the position is in, as follows:
+
address@hidden @code
address@hidden (@var{relx} . @var{rely})
+The coordinates are inside @var{window}.  The numbers @var{relx} and
address@hidden are the equivalent window-relative coordinates for the
+specified position, counting from 0 at the top left corner of the
+window.
+
address@hidden mode-line
+The coordinates are in the mode line of @var{window}.
+
address@hidden header-line
+The coordinates are in the header line of @var{window}.
+
address@hidden vertical-line
+The coordinates are in the vertical line between @var{window} and its
+neighbor to the right.  This value occurs only if the window doesn't
+have a scroll bar; positions in a scroll bar are considered outside the
+window for these purposes.
+
address@hidden left-fringe
address@hidden right-fringe
+The coordinates are in the left or right fringe of the window.
+
address@hidden left-margin
address@hidden right-margin
+The coordinates are in the left or right margin of the window.
+
address@hidden nil
+The coordinates are not in any part of @var{window}.
address@hidden table
+
+The function @code{coordinates-in-window-p} does not require a frame as
+argument because it always uses the frame that @var{window} is on.
address@hidden defun
+
address@hidden Window Tree
address@hidden The Window Tree
address@hidden window tree
+
+  A @dfn{window tree} specifies the layout, size, and relationship
+between all windows in one frame.
+
address@hidden window-tree &optional frame
+This function returns the window tree for frame @var{frame}.
+If @var{frame} is omitted, the selected frame is used.
+
+The return value is a list of the form @code{(@var{root} @var{mini})},
+where @var{root} represents the window tree of the frame's
+root window, and @var{mini} is the frame's minibuffer window.
+
+If the root window is not split, @var{root} is the root window itself.
+Otherwise, @var{root} is a list @code{(@var{dir} @var{edges} @var{w1}
address@hidden ...)} where @var{dir} is @code{nil} for a horizontal split,
+and @code{t} for a vertical split, @var{edges} gives the combined size and
+position of the subwindows in the split, and the rest of the elements
+are the subwindows in the split.  Each of the subwindows may again be
+a window or a list representing a window split, and so on.  The
address@hidden element is a list @code{(@address@hidden address@hidden 
address@hidden bottom})}
+similar to the value returned by @code{window-edges}.
address@hidden defun
+
address@hidden Window Configurations
address@hidden Window Configurations
address@hidden window configurations
address@hidden saving window information
+
+  A @dfn{window configuration} records the entire layout of one
+frame---all windows, their sizes, which buffers they contain, what
+part of each buffer is displayed, and the values of point and the
+mark; also their fringes, margins, and scroll bar settings.  It also
+includes the values of @code{window-min-height},
address@hidden and @code{minibuffer-scroll-window}.  An
+exception is made for point in the selected window for the current
+buffer; its value is not saved in the window configuration.
+
+  You can bring back an entire previous layout by restoring a window
+configuration previously saved.  If you want to record all frames
+instead of just one, use a frame configuration instead of a window
+configuration.  @xref{Frame Configurations}.
+
address@hidden current-window-configuration &optional frame
+This function returns a new object representing @var{frame}'s current
+window configuration.  If @var{frame} is omitted, the selected frame
+is used.
address@hidden defun
+
address@hidden set-window-configuration configuration
+This function restores the configuration of windows and buffers as
+specified by @var{configuration}, for the frame that @var{configuration}
+was created for.
+
+The argument @var{configuration} must be a value that was previously
+returned by @code{current-window-configuration}.  This configuration is
+restored in the frame from which @var{configuration} was made, whether
+that frame is selected or not.  This always counts as a window size
+change and triggers execution of the @code{window-size-change-functions}
+(@pxref{Window Hooks}), because @code{set-window-configuration} doesn't
+know how to tell whether the new configuration actually differs from the
+old one.
+
+If the frame which @var{configuration} was saved from is dead, all this
+function does is restore the three variables @code{window-min-height},
address@hidden and @code{minibuffer-scroll-window}. In this
+case, the function returns @code{nil}.  Otherwise, it returns @code{t}.
+
+Here is a way of using this function to get the same effect
+as @code{save-window-excursion}:
+
address@hidden
address@hidden
+(let ((config (current-window-configuration)))
+  (unwind-protect
+      (progn (split-window-vertically nil)
+             @dots{})
+    (set-window-configuration config)))
address@hidden group
address@hidden example
address@hidden defun
+
address@hidden save-window-excursion address@hidden
+This special form records the window configuration, executes @var{forms}
+in sequence, then restores the earlier window configuration.  The window
+configuration includes, for each window, the value of point and the
+portion of the buffer that is visible.  It also includes the choice of
+selected window.  However, it does not include the value of point in
+the current buffer; use @code{save-excursion} also, if you wish to
+preserve that.
+
+Don't use this construct when @code{save-selected-window} is sufficient.
+
+Exit from @code{save-window-excursion} always triggers execution of the
address@hidden  (It doesn't know how to tell
+whether the restored configuration actually differs from the one in
+effect at the end of the @var{forms}.)
+
+The return value is the value of the final form in @var{forms}.
+For example:
+
address@hidden
address@hidden
+(split-window)
+     @result{} #<window 25 on control.texi>
address@hidden group
address@hidden
+(setq w (selected-window))
+     @result{} #<window 19 on control.texi>
address@hidden group
address@hidden
+(save-window-excursion
+  (delete-other-windows w)
+  (switch-to-buffer "foo")
+  'do-something)
+     @result{} do-something
+     ;; @r{The screen is now split again.}
address@hidden group
address@hidden example
address@hidden defspec
+
address@hidden window-configuration-p object
+This function returns @code{t} if @var{object} is a window configuration.
address@hidden defun
+
address@hidden compare-window-configurations config1 config2
+This function compares two window configurations as regards the
+structure of windows, but ignores the values of point and mark and the
+saved scrolling positions---it can return @code{t} even if those
+aspects differ.
+
+The function @code{equal} can also compare two window configurations; it
+regards configurations as unequal if they differ in any respect, even a
+saved point or mark.
address@hidden defun
+
address@hidden window-configuration-frame config
+This function returns the frame for which the window configuration
address@hidden was made.
address@hidden defun
+
+  Other primitives to look inside of window configurations would make
+sense, but are not implemented because we did not need them.  See the
+file @file{winner.el} for some more operations on windows
+configurations.
+
address@hidden Window Hooks
address@hidden Hooks for Window Scrolling and Changes
address@hidden hooks for window operations
+
+This section describes how a Lisp program can take action whenever a
+window displays a different part of its buffer or a different buffer.
+There are three actions that can change this: scrolling the window,
+switching buffers in the window, and changing the size of the window.
+The first two actions run @code{window-scroll-functions}; the last runs
address@hidden
+
address@hidden window-scroll-functions
+This variable holds a list of functions that Emacs should call before
+redisplaying a window with scrolling.  It is not a normal hook, because
+each function is called with two arguments: the window, and its new
+display-start position.
+
+Displaying a different buffer in the window also runs these functions.
+
+These functions must be careful in using @code{window-end}
+(@pxref{Window Start}); if you need an up-to-date value, you must use
+the @var{update} argument to ensure you get it.
+
address@hidden:} don't use this feature to alter the way the window
+is scrolled.  It's not designed for that, and such use probably won't
+work.
address@hidden defvar
+
address@hidden window-size-change-functions
+This variable holds a list of functions to be called if the size of any
+window changes for any reason.  The functions are called just once per
+redisplay, and just once for each frame on which size changes have
+occurred.
+
+Each function receives the frame as its sole argument.  There is no
+direct way to find out which windows on that frame have changed size, or
+precisely how.  However, if a size-change function records, at each
+call, the existing windows and their sizes, it can also compare the
+present sizes and the previous sizes.
+
+Creating or deleting windows counts as a size change, and therefore
+causes these functions to be called.  Changing the frame size also
+counts, because it changes the sizes of the existing windows.
+
+It is not a good idea to use @code{save-window-excursion} (@pxref{Window
+Configurations}) in these functions, because that always counts as a
+size change, and it would cause these functions to be called over and
+over.  In most cases, @code{save-selected-window} (@pxref{Selecting
+Windows}) is what you need here.
address@hidden defvar
+
address@hidden redisplay-end-trigger-functions
+This abnormal hook is run whenever redisplay in a window uses text that
+extends past a specified end trigger position.  You set the end trigger
+position with the function @code{set-window-redisplay-end-trigger}.  The
+functions are called with two arguments: the window, and the end trigger
+position.  Storing @code{nil} for the end trigger position turns off the
+feature, and the trigger value is automatically reset to @code{nil} just
+after the hook is run.
address@hidden defvar
+
address@hidden set-window-redisplay-end-trigger window position
+This function sets @var{window}'s end trigger position at
address@hidden
address@hidden defun
+
address@hidden window-redisplay-end-trigger &optional window
+This function returns @var{window}'s current end trigger position.
+If @var{window} is @code{nil} or omitted, it uses the selected window.
address@hidden defun
+
address@hidden window-configuration-change-hook
+A normal hook that is run every time you change the window configuration
+of an existing frame.  This includes splitting or deleting windows,
+changing the sizes of windows, or displaying a different buffer in a
+window.  The frame whose window configuration has changed is the
+selected frame when this hook runs.
address@hidden defvar
+
address@hidden
+   arch-tag: 3f6c36e8-df49-4986-b757-417feed88be3
address@hidden ignore