* doc/emacs/files.texi (File Conveniences):
* doc/emacs/misc.texi (Saving Emacs Sessions):
Mention remote-file-name-access-timeout.

* doc/misc/tramp.texi (Frequently Asked Questions): Add note.

* etc/NEWS: Explain use of 'remote-file-name-access-timeout' in
desktop.el and recentf.el.

* lisp/desktop.el (desktop-access-file): New defun.
(desktop-restore-file-buffer): Use it.

* lisp/recentf.el (recentf-access-file): New defun.
(recentf-keep-default-predicate): Use it.

* lisp/net/tramp.el (tramp-handle-access-file): Improve error handling.

* lisp/recentf.el (recentf-expand-file-name): Protect against
stalled remote hosts.  (Bug#57336)

* lisp/desktop.el (desktop-lazy-idle-delay):
* lisp/files.el (dired-kept-versions)
(kept-old-versions, kept-new-versions):
* lisp/filesets.el (filesets-max-submenu-length)
(filesets-max-entry-length, filesets-tree-max-level)
(filesets-query-user-limit):
* lisp/hi-lock.el (hi-lock-file-patterns-range)
(hi-lock-highlight-range):
* lisp/ido.el (ido-max-work-directory-list):
* lisp/image/gravatar.el (gravatar-cache-ttl):
* lisp/imenu.el (imenu-auto-rescan-maxout, imenu-max-items):
* lisp/informat.el (Info-split-threshold):
* lisp/mail/hashcash.el (hashcash-default-payment)
(hashcash-default-accept-payment):
* lisp/mail/mail-hist.el (mail-hist-history-size):
* lisp/mail/smtpmail.el (smtpmail-retries):
* lisp/msb.el (msb-display-most-recently-used):
* lisp/nxml/rng-valid.el (rng-state-cache-distance)
(rng-validate-chunk-size):
* lisp/progmodes/gdb-mi.el (gdb-max-source-window-count):
* lisp/recentf.el (recentf-arrange-by-rules-min-items):
* lisp/simple.el (kill-ring-max, mark-ring-max)
(global-mark-ring-max):
* lisp/tab-line.el (tab-line-tab-name-truncated-max):
* lisp/term.el (term-buffer-maximum-size, term-input-chunk-size):
* lisp/thumbs.el (thumbs-max-image-number)
(thumbs-thumbsdir-max-size, thumbs-relief, thumbs-margin)
(thumbs-image-resizing-step):
* lisp/type-break.el (type-break-interval)
(type-break-good-rest-interval, type-break-query-interval)
(type-break-warning-repeat):
* lisp/vc/compare-w.el (compare-windows-sync-string-size):
* lisp/woman.el (woman-fill-column): Use defcustom :type natnum.

* lisp/emacs-lisp/backtrace.el (backtrace-line-length):
* lisp/doc-view.el (doc-view-conversion-refresh-interval):
Use defcustom :type natnum and allow the nil value.

* lisp/gnus/spam-stat.el (spam-stat-process-directory-age):
Use defcustom :type integer.

* lisp/abbrev.el (abbrev-suggest-hint-threshold):
* lisp/bookmark.el (bookmark-bmenu-file-column)
(bookmark-menu-length):
* lisp/buff-menu.el (Buffer-menu-size-width)
(Buffer-menu-mode-width):
* lisp/calendar/calendar.el (calendar-week-start-day)
(calendar-intermonth-spacing, calendar-column-width)
(calendar-day-digit-width):
* lisp/calc/calc.el (calc-undo-length):
* lisp/calendar/timeclock.el (timeclock-workday):
* lisp/comint.el (comint-buffer-maximum-size)
(comint-input-ring-size):
* lisp/doc-view.el (doc-view-resolution, doc-view-image-width):
* lisp/emacs-lisp/bytecomp.el (byte-compile-docstring-max-column):
* lisp/emacs-lisp/comp.el (native-comp-debug)
(native-comp-verbose, native-comp-async-jobs-number):
* lisp/emacs-lisp/package.el (package-name-column-width)
(package-version-column-width, package-status-column-width)
(package-archive-column-width):
* lisp/eshell/esh-mode.el (eshell-buffer-maximum-lines):
* lisp/frame.el (blink-cursor-blinks):
* lisp/info.el (Info-breadcrumbs-depth):
* lisp/jit-lock.el (jit-lock-chunk-size):
* lisp/kmacro.el (kmacro-ring-max):
* lisp/menu-bar.el (yank-menu-length, yank-menu-max-items):
* lisp/midnight.el (clean-buffer-list-delay-general)
(clean-buffer-list-delay-special):
* lisp/net/dictionary.el (dictionary-port)
(dictionary-proxy-port):
* lisp/net/ldap.el (ldap-default-port):
* lisp/net/pop3.el (pop3-port, pop3-stream-length):
* lisp/net/rcirc.el (rcirc-default-port):
* lisp/net/sieve-manage.el (sieve-manage-default-port):
* lisp/play/spook.el (spook-phrase-default-count):
* lisp/play/tetris.el (tetris-buffer-width)
(tetris-buffer-height, tetris-width, tetris-height)
(tetris-top-left-x, tetris-top-left-y):
* lisp/profiler.el (profiler-sampling-interval):
* lisp/progmodes/sql.el (sql-port):
* lisp/recentf.el (recentf-max-menu-items):
* lisp/strokes.el (strokes-grid-resolution):
* lisp/tab-bar.el (tab-bar-tab-name-truncated-max):
* lisp/term/xterm.el (xterm-max-cut-length):
* lisp/time.el (display-time-interval, world-clock-timer-second):
* lisp/url/url-cache.el (url-cache-expire-time):
* lisp/url/url-cookie.el (url-cookie-save-interval):
* lisp/url/url-history.el (url-history-save-interval):
* lisp/url/url-queue.el (url-queue-parallel-processes)
(url-queue-timeout):
* lisp/url/url-vars.el (url-max-password-attempts)
(url-max-redirections):
* lisp/vc/emerge.el (emerge-min-visible-lines):
* lisp/vc/vc.el (vc-log-show-limit):
* lisp/window.el (window-min-height, window-min-width):
* lisp/winner.el (winner-ring-size): Use :type natnum.

* lisp/savehist.el (savehist-file-modes): Fix setting to nil value and
use :type natnum.

* lisp/recentf.el (recentf-open): New command.  (Bug#56148)
(recentf): New alias.
(recentf, recentf-mode): Update documentation to focus more on the
list of recently opened files and ways of accessing it, instead of
focusing on the menu bar only.
(recentf-list, recentf-enabled-p): Minor doc fixes.

* doc/emacs/files.texi (File Conveniences): Update documentation.

* lisp/recentf.el (recentf--shortcuts-keymap): Add interactive mode
tags for 'recentf-dialog-mode' specific commands.

* lisp/recentf.el (recentf-mode-map): Prefer defvar-keymap.
(recentf--shortcuts-keymap): Prefer keymap-set.

* lisp/recentf.el (recentf-filename-handlers): Set to
'abbreviate-file-name' to get shortened names by default.  (Bug#56123)