children.
@end defun
+@defun window-pixel-height-before-size-change &optional Lisp_Object &optional window
+This function returns the height of window @var{window} in pixels at the
+time @code{window-size-change-functions} was run for the last time on
+@var{window}'s frame (@pxref{Window Hooks}).
+@end defun
+
@cindex window pixel width
@cindex pixel width of a window
@cindex total pixel width of a window
the screen areas spanned by its children.
@end defun
+@defun window-pixel-width-before-size-change &optional Lisp_Object &optional window
+This function returns the width of window @var{window} in pixels at the
+time @code{window-size-change-functions} was run for the last time on
+@var{window}'s frame (@pxref{Window Hooks}).
+@end defun
+
@cindex full-width window
@cindex full-height window
The following functions can be used to determine whether a given
entry (@pxref{Choosing Window Options}), raises that frame if necessary.
@end defun
+@defun display-buffer-reuse-mode-window buffer alist
+This function tries to display @var{buffer} by finding a window
+that is displaying a buffer in a given mode.
+
+If @var{alist} contains a @code{mode} entry, its value is a major mode
+(a symbol) or a list of major modes. If @var{alist} contains no
+@code{mode} entry, the current major mode of @var{buffer} is used. A
+window is a candidate if it displays a buffer that derives from one of
+the given modes.
+
+The behaviour is also controlled by entries for
+@code{inhibit-same-window}, @code{reusable-frames} and
+@code{inhibit-switch-frame} as is done in the function
+@code{display-buffer-reuse-window}.
+
+@end defun
+
@defun display-buffer-pop-up-frame buffer alist
This function creates a new frame, and displays the buffer in that
frame's window. It actually performs the frame creation by calling
The argument @var{configuration} must be a value that was previously
returned by @code{current-window-configuration}. The 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.
+that frame is selected or not. In some rare cases this may trigger
+execution of the @code{window-size-change-functions} (@pxref{Window
+Hooks}) even if the size of windows did not change at all. The
+@code{window-configuration-change-hook} functions will be called if and
+only if at least one window was added to or deleted from the frame.
If the frame from which @var{configuration} was saved is dead, all this
function does is restore the three variables @code{window-min-height},
@end defvar
@defvar 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 at the
-beginning of a redisplay cycle, 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.
+This variable holds a list of functions to be called if the size of any
+window changes for any reason. The functions are called once per
+redisplay, and once for each frame on which size changes have occurred.
+
+Each function receives the frame as its sole argument. To find out
+whether a specific window has changed size, compare the return values of
+@code{window-pixel-width-before-size-change} and
+@code{window-pixel-width} respectively
+@code{window-pixel-height-before-size-change} and
+@code{window-pixel-height} for that window (@pxref{Window Sizes}).
+
+These function are usually only called when at least one window was
+added or has changed size since the last time this hook was run for the
+associated frame. In some rare cases this hook also runs when a window
+that was added intermittently has been deleted afterwards. In these
+cases none of the windows on the frame will appear to have changed its
+size.
You may use @code{save-selected-window} in these functions
(@pxref{Selecting Windows}). However, do not use
@code{save-window-excursion} (@pxref{Window Configurations}); exiting
-that macro counts as a size change, which would cause these functions
-to be called over and over.
+that macro counts as a size change, which would cause these functions to
+be called again.
@end defvar
@defvar 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.
+A normal hook that is run every time the window configuration of a frame
+changes. Window configuration changes include splitting and deleting
+windows and the display of a different buffer in a window. Resizing the
+frame or individual windows do not count as configuration changes. Use
+@code{window-size-change-functions}, see above, when you want to track
+size changes that are not caused by the deletion or creation of windows.
The buffer-local part of this hook is run once for each window on the
affected frame, with the relevant window selected and its buffer