The function calculates frame width one column too small in regard to
displayed buffer which results in text being wrapped around and extra line added
to the frame.

If you look at attached png image you will see backward slash and extra line
added below. Or you can run the attached .el file.

Simple fix I used was to add an extra column to the width of the frame
after I called fit-frame-to-buffer (commented away in the attached file).

The frame created is without any decorations, fringes, borders etc. I wanted as
"bare" X11 window as possible, so the misscalculation might be due to some
missing border or something, I haven't investigated myself.

This probably affects earlier Emacs versions too. I haven't tested other targets,
non-gtk or on other OS.

To reproduce save attached emacs-vision-clock.el somewhere and eval with
Emacs -Q. Example:

emacs -Q -l ./emacs-vision-clock.el --eval "(emacs-vision-clock-run)"&


In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.30, cairo version 1.17.4)
 of 2021-11-17 built on pascal
Repository revision: 1ddebefc9fe178e9e8b4275a45e0eda1bcf7848e
Repository branch: alpha-patch
Windowing system distributor 'The X.Org Foundation', version 11.0.12101001
System Description: Arch Linux

Configured using:
 'configure --with-native-compilation 'CFLAGS=-O2 -march=native
 -mtune=native''

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSYSTEMD LIBXML2 M17N_FLT MODULES NATIVE_COMP NOTIFY
INOTIFY PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS
WEBP X11 XDBE XIM XPM GTK3 ZLIB

Important settings:
  value of $LANG: sv_SE.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media rmc puny
dired dired-loaddefs rfc822 mml mml-sec epa derived epg rfc6068
epg-config gnus-util rmail rmail-loaddefs auth-source cl-seq eieio
eieio-core cl-macs eieio-loaddefs password-cache json map
text-property-search time-date seq gv subr-x byte-opt bytecomp
byte-compile cconv mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils emacs-vision-clock time-stamp help-mode
cl-loaddefs cl-lib iso-transl tooltip eldoc paren electric uniquify
ediff-hook vc-hooks lisp-float-type elisp-mode mwheel term/x-win x-win
term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode lisp-mode prog-mode register
page tab-bar menu-bar rfn-eshadow isearch easymenu timer select
scroll-bar mouse jit-lock font-lock syntax font-core term/tty-colors
frame minibuffer cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice button
loaddefs faces cus-face macroexp files window text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo
move-toolbar gtk x-toolkit x multi-tty make-network-process
native-compile emacs)

Memory information:
((conses 16 71626 11134)
 (symbols 48 6834 0)
 (strings 32 20798 1615)
 (string-bytes 1 700953)
 (vectors 16 14697)
 (vector-slots 8 313076 18657)
 (floats 8 27 32)
 (intervals 56 216 0)
 (buffers 992 11))