@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001,
-@c 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+@c Copyright (C) 1990-1995, 1998-1999, 2001-2011
+@c Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../../info/windows
@node Windows, Frames, Buffers, Top
* 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.
-* Dedicated Windows:: How to avoid displaying another buffer in
+* Choosing Window:: How to choose a window for displaying a buffer.
+* Dedicated Windows:: How to avoid displaying another buffer in
a specific window.
* Window Point:: Each window has its own location of point.
* Window Start and End:: Buffer positions indicating which text is
restores the previously selected window and current buffer. The ordering
of recently selected windows and the buffer list remain unchanged unless
you deliberately change them within @var{forms}, for example, by calling
-@code{select-window} with argument @var{norecord} @code{nil} or omitted
-there.
+@code{select-window} with argument @var{norecord} @code{nil}.
@end defmac
@cindex finding windows
@defun 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.
+selected) among a set of candidate windows. If any full-width windows
+are present, it only considers these.
-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.
-A dedicated window (@pxref{Dedicated Windows}) is never a candidate
-unless the optional argument @var{dedicated} is non-@code{nil}.
+The selected window is returned if it is the only candidate. A
+minibuffer window is never a candidate. A dedicated window
+(@pxref{Dedicated Windows}) is never a candidate unless the optional
+argument @var{dedicated} is non-@code{nil}.
The optional argument @var{frame} specifies which windows are
considered.
specific 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 windows were split.
+ For a particular frame, 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 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
In general, within each set of siblings at any level in the window tree
(@pxref{Window Tree}), the order is left to right, or top to bottom.
-@deffn Command next-window &optional window minibuf all-frames
+@defun next-window &optional window minibuf all-frames
@cindex minibuffer window, and @code{next-window}
This function returns the window following @var{window} in the cyclic
ordering of windows. This is the window @kbd{C-x o} selects if typed
@result{} #<window 56 on windows.texi>
@end group
@end example
-@end deffn
+@end defun
-@deffn Command previous-window &optional window minibuf all-frames
+@defun 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}.
-@end deffn
+@end defun
@deffn Command other-window count &optional all-frames
This function selects another window in the cyclic ordering of windows.
buffer using @code{other-buffer}. If @var{buffer-or-name} is a string
that 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}; see @ref{Auto Major Mode}.
+the variable @code{major-mode}; see @ref{Auto Major Mode}.
-When @code{enable-recursive-minibuffers} is non-@code{nil} and the
-selected window is either the minibuffer window or is dedicated to its
-buffer (@pxref{Dedicated Windows}), @code{switch-to-buffer} calls
+When the selected window is the minibuffer window or is strongly
+dedicated to its buffer (@pxref{Dedicated Windows}), this function calls
@code{pop-to-buffer} (see below) to display the buffer in some other
window.
@deffn Command switch-to-buffer-other-window buffer-or-name &optional norecord
This function makes the buffer specified by @var{buffer-or-name} current
-and displays it in a window not currently selected. It then selects
-that window. The handling of the buffer is the same as in
-@code{switch-to-buffer}.
+and displays it in a window not currently selected, using the function
+@code{pop-to-buffer} (see below).
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.
+If the selected window already displays @var{buffer-or-name}, 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 non-@code{nil}.
@end deffn
-@deffn Command pop-to-buffer buffer-or-name &optional other-window norecord
-This command makes @var{buffer-or-name} the current buffer and switches
+@defun 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. Its frame is
-given the X server's focus, if possible; see @ref{Input Focus}. The return
-value is the buffer that was switched to.
+given the X server's focus, if possible; see @ref{Input Focus}. 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 @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}. @xref{Auto Major Mode}.
-
-If the variable @code{pop-up-frames} is non-@code{nil},
-@code{pop-to-buffer} looks for a window in any visible frame already
-displaying the buffer; if there is one, it selects and returns that
-window. If no such window exists, 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.)
+variable @code{major-mode}. @xref{Auto Major Mode}.
+
+If either of the variables @code{display-buffer-reuse-frames} or
+@code{pop-up-frames} is non-@code{nil}, @code{pop-to-buffer} looks for a
+window in any visible frame already displaying the buffer; if there is
+one, it selects and returns that window. If no such window exists and
+@code{pop-up-frames} is non-@code{nil}, it creates a new frame and
+displays the buffer in it. Otherwise, @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 non-@code{nil}, windows may be
split to create a new window that is different from the original window.
This function updates the buffer list just like @code{switch-to-buffer}
unless @var{norecord} is non-@code{nil}.
-@end deffn
+@end defun
@deffn Command replace-buffer-in-windows &optional buffer-or-name
This function replaces @var{buffer-or-name} in all windows displaying
@defopt display-buffer-reuse-frames
If this variable is non-@code{nil}, @code{display-buffer} searches
-existing frames for a window displaying @var{buffer-or-name}. 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
+visible and iconified frames for a window displaying
+@var{buffer-or-name}. If there is such a window, @code{display-buffer}
+makes that window's frame visible and raises it if necessary, and
+returns the window. If there is no such window or
@code{display-buffer-reuse-frames} is @code{nil}, the behavior of
@code{display-buffer} is determined by the variables described next.
@end defopt
@defopt pop-up-windows
This variable specifies whether @code{display-buffer} is allowed to
-split (@pxref{Splitting Windows}) an existing window . If it is
-non-@code{nil}, @code{display-buffer} tries to the split the largest or
+split (@pxref{Splitting Windows}) an existing window. If this variable
+is non-@code{nil}, @code{display-buffer} tries to split the largest or
least recently used window on the selected frame. (If the selected
-frame is a minibuffer-only frame, it tries to split a window on another
-frame instead.) If @code{pop-up-windows} is nil or the variable
-@code{pop-up-frames} (see below) is non-@code{nil},
+frame is a minibuffer-only frame, @code{display-buffer} tries to split a
+window on another frame instead.) If this variable is @code{nil} or the
+variable @code{pop-up-frames} (see below) is non-@code{nil},
@code{display-buffer} does not split any window.
@end defopt
-@defvar split-window-preferred-function
-This variable specifies how to split a window. Its value, if
-non-@code{nil}, should be a function of one argument, which is a
-window. If this variable specifies a function, @code{display-buffer}
-will call it with one or more candidate windows when it looks for a
-window to split. If the argument window fits, the function is
-expected to split it and return a new window. If the function returns
-@code{nil}, the argument window will not be split.
-
-If the value of this variable is @code{nil}, @code{display-buffer}
-uses the two variables described next to decide whether and which
-window to split.
-@end defvar
+@defopt split-window-preferred-function
+This variable must specify a function with one argument, which is a
+window. The @code{display-buffer} routines will call this function with
+one or more candidate windows when they look for a window to split. The
+function is expected to split that window and return the new window. If
+the function returns @code{nil}, this means that the argument window
+cannot (or shall not) be split.
+
+The default value of @code{split-window-preferred-function} is the
+function @code{split-window-sensibly} described below. If you
+customize this option, bear in mind that the @code{display-buffer}
+routines may call your function up to two times when trying to split a
+window. The argument of the first call is the largest window on the
+chosen frame (as returned by @code{get-largest-window}). If that call
+fails to return a live window, your function is called a second time
+with the least recently used window on that frame (as returned by
+@code{get-lru-window}).
+
+The function specified by this option may try to split any other window
+instead of the argument window. Note that the window selected at the
+time @code{display-buffer} was invoked is still selected when your
+function is called. Hence, you can split the selected window (instead
+of the largest or least recently used one) by simply ignoring the window
+argument in the body of your function. You can even choose to not split
+any window as long as the return value of your function specifies a live
+window or @code{nil}, but you are not encouraged to do so
+unconditionally. If you want @code{display-buffer} to never split any
+windows, set @code{pop-up-windows} to @code{nil}.
+@end defopt
+
+@defun split-window-sensibly window
+This function takes a window as argument and tries to split that window
+in a suitable way. The two variables described next are useful for
+tuning the behavior of this function.
+@end defun
@defopt split-height-threshold
-This variable specifies whether @code{display-buffer} may split a window
-vertically, provided there are multiple windows. If the value is a
-number, @code{display-buffer} splits a window only if it has at least
-this many lines. If no window is tall enough, or if the value of this
-variable is @code{nil}, @code{display-buffer} tries to split some window
-horizontally, subject to restrictions of @code{split-width-threshold}
-(see below). If splitting horizontally is impossible too,
-@code{display-buffer} splits a window vertically only if it's the only
-window on its frame and not the minibuffer window, and only if
-@code{pop-up-windows} is non-@code{nil}.
-
-A window whose height is fixed (@pxref{Resizing Windows}) cannot be
-split vertically by @code{display-buffer}. Also, @code{display-buffer}
-splits a window vertically only if it can accommodate two windows that
-are both at least `window-min-height' lines tall. Moreover, if the
-window that shall be split has a mode line, the window must be at least
-four lines tall in order to make sure that the new window can have a
-mode line as well. If the original window doesn't have a mode line, a
-height of two lines suffices.
+This variable specifies whether @code{split-window-sensibly} may split
+windows vertically. If it is an integer, @code{split-window-sensibly}
+tries to vertically split a window only if it has at least this many
+lines. If the window has less lines, splitting fails, or the value of
+this variable is @code{nil}, @code{split-window-sensibly} will try to
+split the window horizontally, subject to restrictions of
+@code{split-width-threshold} (see below). If splitting horizontally
+fails too and the window is the only window on its frame,
+@code{split-window-sensibly} will try to split the window vertically
+disregarding the value of @code{split-height-threshold}. If this fails
+as well, @code{split-window-sensibly} returns @code{nil}.
+
+@code{split-window-sensibly} does not split vertically a window whose
+height is fixed (@pxref{Resizing Windows}). Also, it vertically splits
+a window only if the space taken up by that window can accommodate two
+windows one above the other that are both at least
+@code{window-min-height} lines tall. Moreover, if the window that shall
+be split has a mode line, @code{split-window-sensibly} does not split
+the window unless the new window can accommodate a mode line too.
@end defopt
@defopt split-width-threshold
-This variable specifies whether @code{display-buffer} may split a window
-horizontally. If the value is a number, @code{display-buffer} may split
-a window if it has at least this many columns. If the value of this
-variable is @code{nil}, @code{display-buffer} will not split any windows
-horizontally. (It still might split some window vertically, though, see
-above.)
-
-A window whose width is fixed (@pxref{Resizing Windows}) cannot be split
-horizontally by @code{display-buffer}. Also, @code{display-buffer}
-splits a window horizontally only if it can accommodate two windows that
-are both at least `window-min-width' columns wide.
+This variable specifies whether @code{split-window-sensibly} may split
+windows horizontally. If it is an integer, @code{split-window-sensibly}
+tries to horizontally split a window only if it has at least this many
+columns. If it is @code{nil}, @code{split-window-sensibly} will not
+split the window horizontally. (It still might split the window
+vertically, though, see above.)
+
+@code{split-window-sensibly} does not split horizontally a window if
+that window's width is fixed (@pxref{Resizing Windows}). Also, it
+horizontally splits a window only if the space that window takes up can
+accommodate two windows side by side that are both at least
+@code{window-min-width} columns wide.
@end defopt
@defopt even-window-heights
@c Emacs 19 feature
@defopt pop-up-frames
-This variable specifies whether @code{display-buffer} makes new frames.
-If it is non-@code{nil}, @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,
-unless the variable's value is @code{graphic-only} and the selected
-frame is not on a graphic display. @xref{Frames}, for more information.
+This variable specifies whether @code{display-buffer} should make new
+frames. If it is non-@code{nil}, @code{display-buffer} looks for a
+window already displaying @var{buffer-or-name} on any visible or
+iconified frame. If it finds such a window, it makes that window's
+frame visible and raises it if necessary, and returns the window.
+Otherwise it makes a new frame, unless the variable's value is
+@code{graphic-only} and the selected frame is not on a graphic display.
+@xref{Frames}, for more information.
Note that the value of @code{pop-up-windows} does not matter if
@code{pop-up-frames} is non-@code{nil}. If @code{pop-up-frames} is
This variable specifies how to make a new frame if @code{pop-up-frames}
is non-@code{nil}.
-Its value should be a function of no arguments. When
+The value of this variable must be a function of no arguments. When
@code{display-buffer} 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
-@code{pop-up-frame-alist}.
+function, which should return a frame. The default value of this
+variable is a function that creates a frame using the parameters
+specified by @code{pop-up-frame-alist} described next.
@end defopt
@defopt pop-up-frame-alist
-This variable holds an alist specifying frame parameters used when
-@code{display-buffer} makes a new frame. @xref{Frame Parameters}, for
-more information about frame parameters.
+This variable holds an alist specifying frame parameters used by the
+default value of @code{pop-up-frame-function} for making new frames.
+@xref{Frame Parameters}, for more information about frame parameters.
@end defopt
@defopt special-display-buffer-names
of frame parameters.
@end defun
-@defvar special-display-function
+@defopt 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
@code{special-display-popup-frame}, see below.
-@end defvar
+@end defopt
@defun special-display-popup-frame buffer &optional args
This function tries to make @var{buffer} visible in a frame of its own.
@end defun
@c Emacs 19 feature
-@defvar display-buffer-function
+@defopt display-buffer-function
This variable is the most flexible way to customize the behavior of
@code{display-buffer}. If it is non-@code{nil}, it should be a function
that @code{display-buffer} calls to do the work. The function should
This variable takes precedence over all the other options described
above.
-@end defvar
+@end defopt
If all options described above fail to produce a suitable window,
@code{display-buffer} tries to reuse an existing window. As a last
@cindex dedicated window
Functions for displaying a buffer can be told to not use specific
-windows by marking these window as @dfn{dedicated} to their buffers.
+windows by marking these windows as @dfn{dedicated} to their buffers.
@code{display-buffer} (@pxref{Choosing Window}) never uses a dedicated
window for displaying another buffer in it. @code{get-lru-window} and
@code{get-largest-window} (@pxref{Selecting Windows}) do not consider
dedicated window, any such window usually gets deleted too, since
@code{kill-buffer} calls @code{replace-buffer-in-windows} for cleaning
up windows. Burying a buffer (@pxref{The Buffer List}) deletes the
-selected window if it is dedicated and shows that buffer. However, if
-that window is the only window on its frame, another buffer is displayed
-in it and the frame is iconified.
+selected window if it is dedicated to that buffer. If, however, that
+window is the only window on its frame, @code{bury-buffer} displays
+another buffer in it and iconifies the frame.
@defun window-dedicated-p &optional window
This function returns non-@code{nil} if @var{window} is dedicated to its
@dfn{strongly} dedicated to its buffer. @code{set-window-buffer}
signals an error when the window it acts upon is strongly dedicated to
its buffer and does not already display the buffer it is asked to
-display. In any other case, @code{set-window-buffer} will display
-another buffer in that window. Other functions do not treat @code{t}
-differently from any non-@code{nil} value.
+display. Other functions do not treat @code{t} differently from any
+non-@code{nil} value.
@end defun
@node Window Point
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
-non-@code{nil} anyway. @xref{Horizontal Scrolling}.
+This 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 non-@code{nil} anyway.
+@xref{Horizontal Scrolling}.
If @var{position} is visible, @code{pos-visible-in-window-p} returns
@code{t} if @var{partially} is @code{nil}; if @var{partially} is
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}).
+functions will adjust the window's vertical scroll position to scroll
+the partially visible row. To disable this feature, Lisp code may bind
+the variable @code{auto-window-vscroll} to @code{nil} (@pxref{Vertical
+Scrolling}).
@deffn Command scroll-up &optional count
This function scrolls the text in the selected window upward
@end defopt
@defopt 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
+This variable is an older variant of @code{scroll-conservatively}.
+The difference is that 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.
@end defopt
@defvar auto-window-vscroll
If this variable is non-@code{nil}, the line-move, scroll-up, and
scroll-down functions will automatically modify the vertical scroll
-position to scroll through display rows that are taller that the height
+position to scroll through display rows that are taller than the height
of the window, for example in the presence of large images.
@end defvar
The following three functions return size information about a window:
@defun 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. The default for
-@var{window} is the selected window.
+This function returns the number of lines in @var{window} (by default
+the selected window), including any mode line and header line.
+The result is almost always less than the value of @code{frame-height}
+for the associated frame, because the latter also includes any echo
+area. Depending on the toolkit in use, the frame height can also
+include the menu bar and tool bar (@pxref{Size and Position}).
+Therefore in general it is not straightforward to compare window and
+frame heights (see @code{window-full-height-p} below).
@example
@group
mode line (if any) or the header line (if any).
@end defun
+@defun window-full-height-p &optional window
+This function returns non-@code{nil} if @var{window} is as tall as the
+frame that contains it. The default for @var{window} is the selected
+window.
+@end defun
+
@defun window-width &optional window
This function returns the number of columns in @var{window}. The
default for @var{window} is the selected window.
function returns @code{nil}.
@end defun
-@defun fit-window-to-buffer &optional window max-height min-height
-This function makes @var{window} the right height to display its
-contents exactly. The default for @var{window} is the selected
-window.
+@deffn Command fit-window-to-buffer &optional window max-height min-height
+This command makes @var{window} the right height to display its
+contents exactly. The default for @var{window} is 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
-@var{min-height} specifies the minimum height for the window;
-@code{nil} means use @code{window-min-height}. All these height
-values include the mode line and/or header line.
-@end defun
+The optional argument @var{max-height} specifies the maximum height the
+window is allowed to be; @code{nil} means use the maximum permissible
+height of a window on @var{window}'s frame. The optional argument
+@var{min-height} specifies the minimum height for the window; @code{nil}
+means use @code{window-min-height}. All these height values include the
+mode line and/or header line.
+
+This function can delete windows when their height shrinks below
+@var{min-height}. It returns non-@code{nil} if it orderly resized
+@var{window}, and @code{nil} otherwise.
+@end deffn
@deffn Command shrink-window-if-larger-than-buffer &optional window
This command shrinks @var{window} vertically to be as small as possible
@end defvar
In addition, you can use @code{jit-lock-register} to register a Font
-Lock fontification function, which will be called whenever part of the
-buffer needs to be refontified (usually because it has been changed).
-@xref{Other Font Lock Variables}.
-
-@ignore
- arch-tag: 3f6c36e8-df49-4986-b757-417feed88be3
-@end ignore
+Lock fontification function, which will be called whenever parts of a
+buffer are (re)fontified because a window was scrolled or its size
+changed. @xref{Other Font Lock Variables}.