Merge from origin/emacs-26

913c001 * lisp/files.el (write-file): Clarify the doc string.  (Bug#3...
d614b84 Fix typos in midnight.el
8c2778a Improve documentation of 'move-file-to-trash'
c7b8a51 ; * doc/lispref/functions.texi (Anonymous Functions): Fix typo.
92296de * src/data.c (Ftype_of): xwidget objects are possible! (bug#3...
a3242cc Improve documentation of Diff mode
39e85a0 Note that lex bound lambda forms are not self-quoting (Bug#33...
fa605f2 Rewrite buffer display related doc-strings and doc
aa55659 Fix call to GlobalMemoryStatusEx in w32.c

# Conflicts:
#	doc/emacs/files.texi
#	src/data.c

10 files changed, 292 insertions, 205 deletions

diff --git a/doc/emacs/files.texi b/doc/emacs/files.texi
index 6c68075ae4a..649fa8bcb4d 100644
--- a/doc/emacs/files.texi
+++ b/doc/emacs/files.texi
@@ -1427,23 +1427,30 @@ manually, type @kbd{M-x diff-mode}.
 @cindex hunk, diff
   The changes specified in a patch are grouped into @dfn{hunks}, which
 are contiguous chunks of text that contain one or more changed lines.
-Hunks can also include unchanged lines to provide context for the
+Hunks usually also include unchanged lines to provide context for the
 changes.  Each hunk is preceded by a @dfn{hunk header}, which
-specifies the old and new line numbers at which the hunk occurs.  Diff
-mode highlights each hunk header, to distinguish it from the actual
-contents of the hunk.
+specifies the old and new line numbers where the hunk's changes occur.
+Diff mode highlights each hunk header, to distinguish it from the
+actual contents of the hunk.
+
+  The first hunk in a patch is preceded by a file header, which shows
+the names of the new and the old versions of the file, and their time
+stamps.  If a patch shows changes for more than one file, each file
+has such a header before the first hunk of that file's changes.
 
 @vindex diff-update-on-the-fly
   You can edit a Diff mode buffer like any other buffer.  (If it is
-read-only, you need to make it writable first.  @xref{Misc Buffer}.)
-Whenever you change a hunk, Diff mode attempts to automatically
-correct the line numbers in the hunk headers, to ensure that the patch
-remains correct.  To disable automatic line number correction,
-change the variable @code{diff-update-on-the-fly} to @code{nil}.
-
-  Diff mode treats each hunk as an error message, similar to
-Compilation mode.  Thus, you can use commands such as @kbd{M-g M-n} to
-visit the corresponding source locations.  @xref{Compilation Mode}.
+read-only, you need to make it writable first; see @ref{Misc Buffer}.)
+Whenever you edit a hunk, Diff mode attempts to automatically correct
+the line numbers in the hunk headers, to ensure that the patch remains
+correct, and could still be applied by @command{patch}.  To disable
+automatic line number correction, change the variable
+@code{diff-update-on-the-fly} to @code{nil}.
+
+  Diff mode arranges for hunks to be treated as compiler error
+messages by @kbd{M-g M-n} and other commands that handle error messages
+(@pxref{Compilation Mode}).  Thus, you can use the compilation-mode
+commands to visit the corresponding source locations.
 
   In addition, Diff mode provides the following commands to navigate,
 manipulate and apply parts of patches:
@@ -1451,7 +1458,8 @@ manipulate and apply parts of patches:
 @table @kbd
 @item M-n
 @findex diff-hunk-next
-Move to the next hunk-start (@code{diff-hunk-next}).
+Move to the next hunk-start (@code{diff-hunk-next}).  With prefix
+argument @var{n}, move forward to the @var{n}th next hunk.
 
 @findex diff-auto-refine-mode
 @cindex mode, Diff Auto-Refine
@@ -1469,19 +1477,22 @@ default, add this to your init file (@pxref{Hooks}):
 
 @item M-p
 @findex diff-hunk-prev
-Move to the previous hunk-start (@code{diff-hunk-prev}).  Like
+Move to the previous hunk-start (@code{diff-hunk-prev}).  With prefix
+argument @var{n}, move back to the @var{n}th previous hunk.  Like
 @kbd{M-n}, this has the side-effect of refining the hunk you move to,
 unless you disable Diff Auto-Refine mode.
 
 @item M-@}
 @findex diff-file-next
 Move to the next file-start, in a multi-file patch
-(@code{diff-file-next}).
+(@code{diff-file-next}).  With prefix argument @var{n}, move forward
+to the start of the @var{n}th next file.
 
 @item M-@{
 @findex diff-file-prev
 Move to the previous file-start, in a multi-file patch
-(@code{diff-file-prev}).
+(@code{diff-file-prev}).  With prefix argument @var{n}, move back to
+the start of the @var{n}th previous file.
 
 @item M-k
 @findex diff-hunk-kill
@@ -1496,7 +1507,10 @@ In a multi-file patch, kill the current file part.
 @findex diff-apply-hunk
 @cindex patches, applying
 Apply this hunk to its target file (@code{diff-apply-hunk}).  With a
-prefix argument of @kbd{C-u}, revert this hunk.
+prefix argument of @kbd{C-u}, revert this hunk, i.e.@: apply the
+reverse of the hunk, which changes the ``new'' version into the ``old''
+version.  If @code{diff-jump-to-old-file} is non-@code{nil}, apply the
+hunk to the ``old'' version of the file instead.
 
 @item C-c C-b
 @findex diff-refine-hunk
@@ -1506,8 +1520,16 @@ of each changed line were actually changed.
 
 @item C-c C-c
 @findex diff-goto-source
+@vindex diff-jump-to-old-file
 Go to the source file and line corresponding to this hunk
-(@code{diff-goto-source}).
+(@code{diff-goto-source}).  By default, this jumps to the ``new''
+version of the file, the one shown first on the file header.
+With a prefix argument, jump to the ``old'' version instead.  If
+@code{diff-jump-to-old-file} is non-@code{nil}, this command by
+default jumps to the ``old'' file, and the meaning of the prefix
+argument is reversed.  If the prefix argument is a number greater than
+8 (e.g., if you type @kbd{C-u C-u C-c C-c}), then this command also
+sets @code{diff-jump-to-old-file} for the next invocation.
 
 @item C-c C-e
 @findex diff-ediff-patch
@@ -1517,41 +1539,47 @@ Start an Ediff session with the patch (@code{diff-ediff-patch}).
 @item C-c C-n
 @findex diff-restrict-view
 Restrict the view to the current hunk (@code{diff-restrict-view}).
-@xref{Narrowing}.  With a prefix argument of @kbd{C-u}, restrict the
+@xref{Narrowing}.  With a prefix argument, restrict the
 view to the current file of a multiple-file patch.  To widen again,
 use @kbd{C-x n w} (@code{widen}).
 
 @item C-c C-r
 @findex diff-reverse-direction
 Reverse the direction of comparison for the entire buffer
-(@code{diff-reverse-direction}).
+(@code{diff-reverse-direction}).  With a prefix argument, reverse the
+direction only inside the current region (@pxref{Mark}).  Reversing
+the direction means changing the hunks and the file-start headers to
+produce a patch that would change the ``new'' version into the ``old''
+one.
 
 @item C-c C-s
 @findex diff-split-hunk
-Split the hunk at point (@code{diff-split-hunk}).  This is for
-manually editing patches, and only works with the @dfn{unified diff
-format} produced by the @option{-u} or @option{--unified} options to
-the @command{diff} program.  If you need to split a hunk in the
-@dfn{context diff format} produced by the @option{-c} or
-@option{--context} options to @command{diff}, first convert the buffer
-to the unified diff format with @kbd{C-c C-u}.
+Split the hunk at point (@code{diff-split-hunk}) into two separate
+hunks.  This inserts a hunk header and modifies the header of the
+current hunk.  This command is useful for manually editing patches,
+and only works with the @dfn{unified diff format} produced by the
+@option{-u} or @option{--unified} options to the @command{diff}
+program.  If you need to split a hunk in the @dfn{context diff format}
+produced by the @option{-c} or @option{--context} options to
+@command{diff}, first convert the buffer to the unified diff format
+with @kbd{C-c C-u}.
 
 @item C-c C-d
 @findex diff-unified->context
 Convert the entire buffer to the @dfn{context diff format}
 (@code{diff-unified->context}).  With a prefix argument, convert only
-the text within the region.
+the hunks within the region.
 
 @item C-c C-u
 @findex diff-context->unified
 Convert the entire buffer to unified diff format
 (@code{diff-context->unified}).  With a prefix argument, convert
 unified format to context format.  When the mark is active, convert
-only the text within the region.
+only the hunks within the region.
 
 @item C-c C-w
 @findex diff-ignore-whitespace-hunk
-Re-diff the current hunk, disregarding changes in whitespace
+Re-generate the current hunk, disregarding changes in whitespace
 (@code{diff-ignore-whitespace-hunk}).
 
 @item C-x 4 A
@@ -1582,7 +1610,8 @@ that whitespace in both the patch and the patched source file(s).
 This command does not save the modifications that it makes, so you can
 decide whether to save the changes (the list of modified files is
 displayed in the echo area).  With a prefix argument, it tries to
-modify the original source files rather than the patched source files.
+modify the original (``old'') source files rather than the patched
+(``new'') source files.
 
 @node Copying and Naming
 @section Copying, Naming and Renaming Files
@@ -1668,10 +1697,12 @@ Dired rather than @code{delete-file}.  @xref{Dired Deletion}.
 
 @cindex trash
 @cindex recycle bin
+@findex move-file-to-trash
   @kbd{M-x move-file-to-trash} moves a file into the system
 @dfn{Trash} (or @dfn{Recycle Bin}).  This is a facility available on
 most operating systems; files that are moved into the Trash can be
-brought back later if you change your mind.
+brought back later if you change your mind.  (The way to restore
+trashed files is system-dependent.)
 
 @vindex delete-by-moving-to-trash
   By default, Emacs deletion commands do @emph{not} use the Trash.  To
diff --git a/doc/lispref/functions.texi b/doc/lispref/functions.texi
index 69e9919f708..bf0354c90da 100644
--- a/doc/lispref/functions.texi
+++ b/doc/lispref/functions.texi
@@ -1082,15 +1082,18 @@ This macro returns an anonymous function with argument list
 @var{args}, documentation string @var{doc} (if any), interactive spec
 @var{interactive} (if any), and body forms given by @var{body}.
 
-In effect, this macro makes @code{lambda} forms self-quoting:
-evaluating a form whose @sc{car} is @code{lambda} yields the form
-itself:
+Under dynamic binding, this macro effectively makes @code{lambda}
+forms self-quoting: evaluating a form whose @sc{car} is @code{lambda}
+yields the form itself:
 
 @example
 (lambda (x) (* x x))
      @result{} (lambda (x) (* x x))
 @end example
 
+Note that when evaluating under lexical binding the result is a
+closure object (@pxref{Closures}).
+
 The @code{lambda} form has one other effect: it tells the Emacs
 evaluator and byte-compiler that its argument is a function, by using
 @code{function} as a subroutine (see below).
diff --git a/doc/lispref/windows.texi b/doc/lispref/windows.texi
index 9301fdfa9d6..bce2459a2f5 100644
--- a/doc/lispref/windows.texi
+++ b/doc/lispref/windows.texi
@@ -2747,8 +2747,8 @@ the buffer.  This entry is used by
 
 @vindex reusable-frames@r{, a buffer display action alist entry}
 @item reusable-frames
-The value specifies the frame(s) to search for a window that can be
-reused because it already displays the buffer.  It can be set as
+The value specifies the set of frames to search for a window that can
+be reused because it already displays the buffer.  It can be set as
 follows:
 
 @itemize @bullet
@@ -2792,17 +2792,20 @@ entry.
 @vindex window-height@r{, a buffer display action alist entry}
 @item window-height
 The value specifies whether and how to adjust the height of the chosen
-window, and can have the following values:
+window and can be one of the following:
 
 @itemize @bullet
 @item
 @code{nil} means to leave the height of the chosen window alone.
 
 @item
-A number specifies the desired height of the chosen window.  An
-integer specifies the number of lines of the window.  A floating-point
-number gives the fraction of the window's height with respect to the
-height of the frame's root window.
+An integer number specifies the desired total height of the chosen
+window in lines.
+
+@item
+A floating-point number specifies the fraction of the chosen window's
+desired total height with respect to the total height of its frame's
+root window.
 
 @item
 If the value specifies a function, that function is called with one
@@ -2812,7 +2815,11 @@ are @code{shrink-window-if-larger-than-buffer} and
 @code{fit-window-to-buffer}, see @ref{Resizing Windows}.
 @end itemize
 
-All action functions that choose a window should process this entry.
+By convention, the height of the chosen window is adjusted only if the
+window is part of a vertical combination (@pxref{Windows and Frames})
+to avoid changing the height of other, unrelated windows.  Also, this
+entry should be processed only under certain conditions which are
+specified right below this list.
 
 @vindex window-width@r{, a buffer display action alist entry}
 @item window-width
@@ -2825,10 +2832,13 @@ value can be one of the following:
 @code{nil} means to leave the width of the chosen window alone.
 
 @item
-A number specifies the desired width of the chosen window.  An integer
-specifies the number of columns of the window.  A floating-point
-number gives the fraction of the window's width with respect to the
-width of the frame's root window.
+An integer specifies the desired total width of the chosen window in
+columns.
+
+@item
+A floating-point number specifies the fraction of the chosen window's
+desired total width with respect to the total width of the frame's
+root window.
 
 @item
 If the value specifies a function, that function is called with one
@@ -2836,16 +2846,21 @@ argument---the chosen window.  The function is supposed to adjust the
 width of the window; its return value is ignored.
 @end itemize
 
-All action functions that choose a window should process this entry.
+By convention, the width of the chosen window is adjusted only if the
+window is part of a horizontal combination (@pxref{Windows and
+Frames}) to avoid changing the width of other, unrelated windows.
+Also, this entry should be processed under only certain conditions
+which are specified right below this list.
 
 @vindex preserve-size@r{, a buffer display action alist entry}
 @item preserve-size
 If non-@code{nil} such an entry tells Emacs to preserve the size of
 the window chosen (@pxref{Preserving Window Sizes}).  The value should
-be either @code{(t . nil)} to preserve the width of the window,
-@code{(nil . t)} to preserve its height or @code{(t . t)} to preserve
-both its width and its height.  All action functions that choose a
-window should process this entry.
+be either @w{@code{(t . nil)}} to preserve the width of the window,
+@w{@code{(nil . t)}} to preserve its height or @w{@code{(t . t)}} to
+preserve both, its width and its height.  This entry should be
+processed only under certain conditions which are specified right
+after this list.
 
 @vindex pop-up-frame-parameters@r{, a buffer display action alist entry}
 @item pop-up-frame-parameters
@@ -2900,6 +2915,15 @@ will display the buffer.  @code{display-buffer-no-window} is the only
 action function that cares about this entry.
 @end table
 
+By convention, the entries @code{window-height}, @code{window-width}
+and @code{preserve-size} are applied after the chosen window's buffer
+has been set up and if and only if that window never showed another
+buffer before.  More precisely, the latter means that the window must
+have been either created by the current @code{display-buffer} call or
+the window was created earlier by @code{display-buffer} to show the
+buffer and never was used to show another buffer until it was reused
+by the current invocation of @code{display-buffer}.
+
 
 @node Choosing Window Options
 @subsection Additional Options for Displaying Buffers
diff --git a/lisp/files.el b/lisp/files.el
index 0f0c7d1559a..47f7acf92cc 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -4324,12 +4324,15 @@ the old visited file has been renamed to the new name FILENAME."
   "Write current buffer into file FILENAME.
 This makes the buffer visit that file, and marks it as not modified.
 
-If you specify just a directory name as FILENAME, that means to use
-the default file name but in that directory.  You can also yank
-the default file name into the minibuffer to edit it, using \\<minibuffer-local-map>\\[next-history-element].
-
-If the buffer is not already visiting a file, the default file name
-for the output file is the buffer name.
+Interactively, prompt for FILENAME.
+If you specify just a directory name as FILENAME, that means to write
+to a file in that directory.  In this case, the base name of the file
+is the same as that of the file visited in the buffer, or the buffer
+name sans leading directories, if any, if the buffer is not already
+visiting a file.
+
+You can also yank the file name into the minibuffer to edit it,
+using \\<minibuffer-local-map>\\[next-history-element].
 
 If optional second arg CONFIRM is non-nil, this function
 asks for confirmation before overwriting an existing file.
diff --git a/lisp/midnight.el b/lisp/midnight.el
index 82994c579f7..7c4096c326f 100644
--- a/lisp/midnight.el
+++ b/lisp/midnight.el
@@ -64,7 +64,7 @@ the time when it is run.")
 
 (defcustom clean-buffer-list-delay-general 3
   "The number of days before any buffer becomes eligible for autokilling.
-The autokilling is done by `clean-buffer-list' when is it in `midnight-hook'.
+The autokilling is done by `clean-buffer-list' when it is in `midnight-hook'.
 Currently displayed and/or modified (unsaved) buffers, as well as buffers
 matching `clean-buffer-list-kill-never-buffer-names' and
 `clean-buffer-list-kill-never-regexps' are excluded."
@@ -81,7 +81,7 @@ displayed more than this many seconds ago."
   "List of regexps saying which buffers will be killed at midnight.
 If buffer name matches a regexp in the list and the buffer was not displayed
 in the last `clean-buffer-list-delay-special' seconds, it is killed by
-`clean-buffer-list' when is it in `midnight-hook'.
+`clean-buffer-list' when it is in `midnight-hook'.
 If a member of the list is a cons, its `car' is the regexp and its `cdr' is
 the number of seconds to use instead of `clean-buffer-list-delay-special'.
 See also `clean-buffer-list-kill-buffer-names',
@@ -101,7 +101,7 @@ if the buffer should be killed by `clean-buffer-list'."
   "List of strings saying which buffers will be killed at midnight.
 Buffers with names in this list, which were not displayed in the last
 `clean-buffer-list-delay-special' seconds, are killed by `clean-buffer-list'
-when is it in `midnight-hook'.
+when it is in `midnight-hook'.
 If a member of the list is a cons, its `car' is the name and its `cdr' is
 the number of seconds to use instead of `clean-buffer-list-delay-special'.
 See also `clean-buffer-list-kill-regexps',
diff --git a/lisp/subr.el b/lisp/subr.el
index aaf8909e0c1..1fd86fd7495 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -93,12 +93,13 @@ Info node `(elisp)Specification List' for details."
   `(put (quote ,symbol) 'edebug-form-spec (quote ,spec)))
 
 (defmacro lambda (&rest cdr)
-  "Return a lambda expression.
-A call of the form (lambda ARGS DOCSTRING INTERACTIVE BODY) is
-self-quoting; the result of evaluating the lambda expression is the
-expression itself.  The lambda expression may then be treated as a
-function, i.e., stored as the function value of a symbol, passed to
-`funcall' or `mapcar', etc.
+  "Return an anonymous function.
+Under dynamic binding, a call of the form (lambda ARGS DOCSTRING
+INTERACTIVE BODY) is self-quoting; the result of evaluating the
+lambda expression is the expression itself.  Under lexical
+binding, the result is a closure.  Regardless, the result is a
+function, i.e., it may be stored as the function value of a
+symbol, passed to `funcall' or `mapcar', etc.
 
 ARGS should take the same form as an argument list for a `defun'.
 DOCSTRING is an optional documentation string.
diff --git a/lisp/window.el b/lisp/window.el
index c0eeba7261d..172ee729978 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -6772,7 +6772,11 @@ live."
        ((or (eq type 'frame)
             (and (eq (car quit-restore) 'same)
                  (eq (nth 1 quit-restore) 'frame)))
-        ;; Adjust size of frame if asked for.
+        ;; A window that never showed another buffer but BUFFER ever
+        ;; since it was created on a new frame.
+        ;;
+        ;; Adjust size of frame if asked for.  We probably should do
+        ;; that only for a single window frame.
         (cond
          ((not size))
          ((consp size)
@@ -6791,7 +6795,10 @@ live."
        ((or (eq type 'window)
             (and (eq (car quit-restore) 'same)
                  (eq (nth 1 quit-restore) 'window)))
-        ;; Adjust height of window if asked for.
+        ;; A window that never showed another buffer but BUFFER ever
+        ;; since it was created on an existing frame.
+        ;;
+        ;; Adjust width and/or height of window if asked for.
         (cond
          ((not height))
          ((numberp height)
@@ -6887,31 +6894,41 @@ The actual non-nil value of this variable will be copied to the
   "Custom type for `display-buffer' actions.")
 
 (defvar display-buffer-overriding-action '(nil . nil)
-  "User-defined overriding action to perform to display a buffer.
-This action overrides all the other actions in the action variables
-and arguments passed to `display-buffer'.
-Value should be a cons cell (FUNCTION . ALIST), where FUNCTION is
-a function or a list of functions.  Each function should accept
-two arguments: a buffer to display and an alist similar to ALIST.
-The default value is empty.
-See `display-buffer' for details.")
+  "Overriding action for buffer display.
+This action overrides all the other actions in the action
+variables and arguments passed to `display-buffer'.  The value
+should be a cons cell (FUNCTIONS . ALIST), where FUNCTIONS is a
+function or a list of functions.  Each function should accept two
+arguments: a buffer to display and an alist similar to ALIST.
+See `display-buffer' for details.
+
+This variable is not intended for user customization.  Lisp
+programs should never set this variable permanently but may bind
+it around calls of buffer display functions like `display-buffer'
+or `pop-to-buffer'.  Since such a binding will affect any nested
+buffer display requests, this variable should be used with utmost
+care.")
 (put 'display-buffer-overriding-action 'risky-local-variable t)
 
 (defcustom display-buffer-alist nil
   "Alist of user-defined conditional actions for `display-buffer'.
-Its value takes effect before `display-buffer-base-action'
-and `display-buffer-fallback-action', but after
+Its value takes effect before processing the ACTION argument of
+`display-buffer' and before `display-buffer-base-action' and
+`display-buffer-fallback-action', but after
 `display-buffer-overriding-action', which see.
-If non-nil, this is a list of elements (CONDITION . ACTION), where:
+
+If non-nil, this is an alist of elements (CONDITION . ACTION),
+where:
 
  CONDITION is either a regexp matching buffer names, or a
   function that takes two arguments - a buffer name and the
   ACTION argument of `display-buffer' - and returns a boolean.
 
- ACTION is a cons cell (FUNCTION . ALIST), where FUNCTION is a
-  function or a list of functions.  Each such function should
-  accept two arguments: a buffer to display and an alist of the
-  same form as ALIST.  See `display-buffer' for details.
+ ACTION is a cons cell (FUNCTIONS . ALIST), where FUNCTIONS is an
+  action function or a list of action functions and ALIST is an
+  action alist.  Each such action function should accept two
+  arguments: a buffer to display and an alist of the same form as
+  ALIST.  See `display-buffer' for details.
 
 `display-buffer' scans this alist until it either finds a
 matching regular expression or the function specified by a
@@ -6931,11 +6948,12 @@ associated action to the list of actions it will try."
 This is the default action used by `display-buffer' if no other
 actions are specified or all fail, before falling back on
 `display-buffer-fallback-action'.
-It should be a cons cell (FUNCTION . ALIST), where FUNCTION is a
-function or a list of functions.  Each function should accept two
-arguments: a buffer to display and an alist similar to ALIST.
-The default value is empty.
-See `display-buffer' for details."
+
+It should be a cons cell (FUNCTIONS . ALIST), where FUNCTIONS is
+an action function or a list of action functions and ALIST is an
+action alist.  Each such action function should accept two
+arguments: a buffer to display and an alist of the same form as
+ALIST.  See `display-buffer' for details."
   :type display-buffer--action-custom-type
   :risky t
   :version "24.1"
@@ -6951,17 +6969,20 @@ See `display-buffer' for details."
      display-buffer-pop-up-frame))
   "Default fallback action for `display-buffer'.
 This is the action used by `display-buffer' if no other actions
-specified, e.g. by the user options `display-buffer-alist' or
-`display-buffer-base-action', or they all fail.  See `display-buffer'.")
+have been specified, for example, by the user options
+`display-buffer-alist' or `display-buffer-base-action', or they
+all fail.  It should never be set by programs or users.  See
+`display-buffer'.")
 (put 'display-buffer-fallback-action 'risky-local-variable t)
 
 (defun display-buffer-assq-regexp (buffer-name alist action)
   "Retrieve ALIST entry corresponding to BUFFER-NAME.
-This returns the cdr of the ALIST entry if either its key is a
-string that matches BUFFER-NAME, as reported by `string-match-p';
-or if the key is a function that returns a non-nil when called
-with 3 arguments: the ALIST key, BUFFER-NAME, and ACTION.
-ACTION should have the form of the action argument passed to `display-buffer'."
+This returns the cdr of the alist entry ALIST if either its key
+is a string that matches BUFFER-NAME, as reported by
+`string-match-p'; or if the key is a function that returns
+non-nil when called with three arguments: the ALIST key,
+BUFFER-NAME and ACTION.  ACTION should have the form of the
+action argument passed to `display-buffer'."
   (catch 'match
     (dolist (entry alist)
       (let ((key (car entry)))
@@ -6990,100 +7011,99 @@ fails, call `display-buffer-pop-up-frame'.")
 
 (defun display-buffer (buffer-or-name &optional action frame)
   "Display BUFFER-OR-NAME in some window, without selecting it.
-BUFFER-OR-NAME must be a buffer or the name of an existing
-buffer.  Return the window chosen for displaying BUFFER-OR-NAME,
-or nil if no such window is found.
-
-Optional argument ACTION, if non-nil, should specify a display
-action.  Its form is described below.
-
-Optional argument FRAME, if non-nil, acts like an additional
-ALIST entry (reusable-frames . FRAME) to the action list of ACTION,
-specifying the frame(s) to search for a window that is already
-displaying the buffer.  See `display-buffer-reuse-window'.
-
-If ACTION is non-nil, it should have the form (FUNCTION . ALIST),
-where FUNCTION is either a function or a list of functions, and
-ALIST is an arbitrary association list (alist).
-
-Each such function should accept two arguments: the buffer to
-display and an alist.  Based on those arguments, it should
-display the buffer and return the window.  If the caller is
-prepared to handle the case of not displaying the buffer
-and returning nil from `display-buffer' it should pass
-\(allow-no-window . t) as an element of the ALIST.
-
-The `display-buffer' function builds a function list and an alist
-by combining the functions and alists specified in
+BUFFER-OR-NAME must be a buffer or a string naming a live buffer.
+Return the window chosen for displaying that buffer, or nil if no
+such window is found.
+
+Optional argument ACTION, if non-nil, should specify a buffer
+display action of the form (FUNCTIONS . ALIST).  FUNCTIONS is
+either an \"action function\" or a possibly empty list of action
+functions.  ALIST is a possibly empty \"action alist\".
+
+An action function is a function that accepts two arguments: the
+buffer to display and an action alist.  Based on those arguments,
+it should try to display the buffer in a window and return that
+window.  An action alist is an association list mapping symbols
+to values.  Action functions use the action alist passed to them
+to fine-tune their behaviors.
+
+`display-buffer' builds a list of action functions and an action
+alist by combining any action functions and alists specified by
 `display-buffer-overriding-action', `display-buffer-alist', the
 ACTION argument, `display-buffer-base-action', and
 `display-buffer-fallback-action' (in order).  Then it calls each
 function in the combined function list in turn, passing the
-buffer as the first argument and the combined alist as the second
-argument, until one of the functions returns non-nil.
-
-If ACTION is nil, the function list and the alist are built using
-only the other variables mentioned above.
-
-Available action functions include:
- `display-buffer-same-window'
- `display-buffer-reuse-window'
- `display-buffer-pop-up-frame'
- `display-buffer-in-child-frame'
- `display-buffer-pop-up-window'
- `display-buffer-in-previous-window'
- `display-buffer-use-some-window'
- `display-buffer-use-some-frame'
-
-Recognized alist entries include:
-
- `inhibit-same-window' -- A non-nil value prevents the same
-                          window from being used for display.
-
- `inhibit-switch-frame' -- A non-nil value prevents any other
-                           frame from being raised or selected,
-                           even if the window is displayed there.
-
- `reusable-frames' -- Value specifies frame(s) to search for a
-                      window that already displays the buffer.
-                      See `display-buffer-reuse-window'.
-
- `pop-up-frame-parameters' -- Value specifies an alist of frame
-                              parameters to give a new frame, if
-                              one is created.
-
- `window-height' -- Value specifies either an integer (the number
-    of lines of a new window), a floating point number (the
-    fraction of a new window with respect to the height of the
-    frame's root window) or a function to be called with one
-    argument - a new window.  The function is supposed to adjust
-    the height of the window; its return value is ignored.
-    Suitable functions are `shrink-window-if-larger-than-buffer'
-    and `fit-window-to-buffer'.
-
- `window-width' -- Value specifies either an integer (the number
-    of columns of a new window), a floating point number (the
-    fraction of a new window with respect to the width of the
-    frame's root window) or a function to be called with one
-    argument - a new window.  The function is supposed to adjust
-    the width of the window; its return value is ignored.
-
- `allow-no-window' -- A non-nil value indicates readiness for the case
-    of not displaying the buffer and FUNCTION can safely return
-    a non-window value to suppress displaying.
-
- `preserve-size' -- Value should be either (t . nil) to
-    preserve the width of the window, (nil . t) to preserve its
-    height or (t . t) to preserve both.
-
- `window-parameters' -- Value specifies an alist of window
-                        parameters to give the chosen window.
-
-The ACTION argument to `display-buffer' can also have a non-nil
-and non-list value.  This means to display the buffer in a window
-other than the selected one, even if it is already displayed in
-the selected window.  If called interactively with a prefix
-argument, ACTION is t."
+buffer as the first argument and the combined action alist as the
+second argument, until one of the functions returns non-nil.
+
+Action functions and the action they try to perform are:
+ `display-buffer-same-window' -- Use the selected window.
+ `display-buffer-reuse-window' -- Use a window already showing
+    the buffer.
+ `display-buffer-in-previous-window' -- Use a window that did
+    show the buffer before.
+ `display-buffer-use-some-window' -- Use some existing window.
+ `display-buffer-pop-up-window' -- Pop up a new window.
+ `display-buffer-below-selected' -- Use or pop up a window below
+    the selected one.
+ `display-buffer-at-bottom' -- Use or pop up a window at the
+    bottom of the selected frame.
+ `display-buffer-pop-up-frame' -- Show the buffer on a new frame.
+ `display-buffer-in-child-frame' -- Show the buffer in a
+    child frame.
+ `display-buffer-no-window' -- Do not display the buffer and
+    have `display-buffer' return nil immediately.
+
+Action alist entries are:
+ 'inhibit-same-window' -- A non-nil value prevents the same
+    window from being used for display.
+ 'inhibit-switch-frame' -- A non-nil value prevents any frame
+    used for showing the buffer from being raised or selected.
+ 'reusable-frames' -- The value specifies the set of frames to
+    search for a window that already displays the buffer.
+    Possible values are nil (the selected frame), t (any live
+    frame), visible (any visible frame), 0 (any visible or
+    iconified frame) or an existing live frame.
+ 'pop-up-frame-parameters' -- The value specifies an alist of
+    frame parameters to give a new frame, if one is created.
+ 'window-height' -- The value specifies the desired height of the
+    window chosen and is either an integer (the total height of
+    the window), a floating point number (the fraction of its
+    total height with respect to the total height of the frame's
+    root window) or a function to be called with one argument -
+    the chosen window.  The function is supposed to adjust the
+    height of the window; its return value is ignored.  Suitable
+    functions are `shrink-window-if-larger-than-buffer' and
+    `fit-window-to-buffer'.
+ 'window-width' -- The value specifies the desired width of the
+    window chosen and is either an integer (the total width of
+    the window), a floating point number (the fraction of its
+    total width with respect to the width of the frame's root
+    window) or a function to be called with one argument - the
+    chosen window.  The function is supposed to adjust the width
+    of the window; its return value is ignored.
+ 'preserve-size' -- The value should be either (t . nil) to
+    preserve the width of the chosen window, (nil . t) to
+    preserve its height or (t . t) to preserve its height and
+    width in future changes of the window configuration.
+ 'window-parameters' -- The value specifies an alist of window
+    parameters to give the chosen window.
+ 'allow-no-window' -- A non-nil value means that `display-buffer'
+    may not display the buffer and return nil immediately.
+
+The entries 'window-height', 'window-width' and 'preserve-size'
+are applied only when the window used for displaying the buffer
+never showed another buffer before.
+
+The ACTION argument can also have a non-nil and non-list value.
+This means to display the buffer in a window other than the
+selected one, even if it is already displayed in the selected
+window.  If called interactively with a prefix argument, ACTION
+is t.  Non-interactive calls should always supply a list or nil.
+
+The optional third argument FRAME, if non-nil, acts like a
+\(reusable-frames . FRAME) entry appended to the action alist
+specified by the ACTION argument."
   (interactive (list (read-buffer "Display buffer: " (other-buffer))
                      (if current-prefix-arg t)))
   (let ((buffer (if (bufferp buffer-or-name)
@@ -7141,9 +7161,10 @@ its documentation for additional customization information."
 ;;; `display-buffer' action functions:
 
 (defun display-buffer-use-some-frame (buffer alist)
-  "Display BUFFER in an existing frame that meets a predicate
-\(by default any frame other than the current frame).  If
-successful, return the window used; otherwise return nil.
+  "Display BUFFER in an existing frame that meets a predicate.
+The default predicate is to use any frame other than the selected
+frame.  If successful, return the window used; otherwise return
+nil.
 
 If ALIST has a non-nil `inhibit-switch-frame' entry, avoid
 raising the frame.
@@ -7156,17 +7177,18 @@ predicate.
 If ALIST has a non-nil `inhibit-same-window' entry, avoid using
 the currently selected window (only useful with a frame-predicate
 that allows the selected frame)."
-  (let* ((predicate (or (cdr (assq 'frame-predicate alist))
-                        (lambda (frame)
-                          (and
-                           (not (eq frame (selected-frame)))
-                           (not (window-dedicated-p
-                                 (or
-                                  (get-lru-window frame)
-                                  (frame-first-window frame)))))
-                          )))
+  (let* ((predicate
+          (or (cdr (assq 'frame-predicate alist))
+              (lambda (frame)
+                (and (not (eq frame (selected-frame)))
+                     (not (window-dedicated-p
+                           (or (get-lru-window frame)
+                               (frame-first-window frame))))))))
          (frame (car (filtered-frame-list predicate)))
-         (window (and frame (get-lru-window frame nil (cdr (assq 'inhibit-same-window alist))))))
+         (window
+          (and frame
+               (get-lru-window
+                frame nil (cdr (assq 'inhibit-same-window alist))))))
     (when window
       (prog1
           (window--display-buffer
diff --git a/src/data.c b/src/data.c
index f8b991e8981..0980cf99886 100644
--- a/src/data.c
+++ b/src/data.c
@@ -267,11 +267,13 @@ for example, (type-of 1) returns `integer'.  */)
           }
         case PVEC_MODULE_FUNCTION:
           return Qmodule_function;
+        case PVEC_XWIDGET:
+          return Qxwidget;
+        case PVEC_XWIDGET_VIEW:
+          return Qxwidget_view;
         /* "Impossible" cases.  */
         case PVEC_MISC_PTR:
-        case PVEC_XWIDGET:
         case PVEC_OTHER:
-        case PVEC_XWIDGET_VIEW:
         case PVEC_SUB_CHAR_TABLE:
         case PVEC_FREE: ;
         }
@@ -3930,8 +3932,8 @@ syms_of_data (void)
   DEFSYM (Qmarker, "marker");
   DEFSYM (Qoverlay, "overlay");
   DEFSYM (Qfinalizer, "finalizer");
-#ifdef HAVE_MODULES
   DEFSYM (Qmodule_function, "module-function");
+#ifdef HAVE_MODULES
   DEFSYM (Quser_ptr, "user-ptr");
 #endif
   DEFSYM (Qfloat, "float");
@@ -3954,6 +3956,8 @@ syms_of_data (void)
   DEFSYM (Qfont_entity, "font-entity");
   DEFSYM (Qfont_object, "font-object");
   DEFSYM (Qterminal, "terminal");
+  DEFSYM (Qxwidget, "xwidget");
+  DEFSYM (Qxwidget_view, "xwidget-view");
 
   DEFSYM (Qdefun, "defun");
 
diff --git a/src/w32.c b/src/w32.c
index 3eaa1279dd6..26cfae7a6af 100644
--- a/src/w32.c
+++ b/src/w32.c
@@ -7225,6 +7225,7 @@ system_process_attributes (Lisp_Object pid)
                          code_convert_string_norecord (tem, Vlocale_coding_system, 0)),
                  attrs);
 
+  memstex.dwLength = sizeof (memstex);
   if (global_memory_status_ex (&memstex))
 #if __GNUC__ || (defined (_MSC_VER) && _MSC_VER >= 1300)
     totphys = memstex.ullTotalPhys / 1024.0;
diff --git a/src/xwidget.c b/src/xwidget.c
index 4739993e729..6faac107518 100644
--- a/src/xwidget.c
+++ b/src/xwidget.c
@@ -1014,8 +1014,6 @@ syms_of_xwidget (void)
   defsubr (&Sxwidget_buffer);
   defsubr (&Sset_xwidget_plist);
 
-  DEFSYM (Qxwidget, "xwidget");
-
   DEFSYM (QCxwidget, ":xwidget");
   DEFSYM (QCtitle, ":title");