Message-ID: <m2a7s1mavt.fsf@gmail.com>
--text follows this line--

1. Create ~/undecorated.el file with following content:

  (add-to-list 'default-frame-alist '(undecorated . t))

2. Start Emacs:

   $ emacs -Q --load ~/undecorated.el

   or (if you don't want to create files)

   $ emacs -q --execute "(add-to-list 'default-frame-alist '(undecorated .
t))"

3. Try one of the following actions

3.1. M-x toggle-frame-fullsreen

     Frames' window (in macOS sense) becomes fullscreen. But it doesn't
     cover all screen, instead it remains of the same default size with
     black area around.

3.2. Use Spectacle.app (or similar application for resizing windows in
     macOS)

     Frame is not resized.

In both cases I expect frames to properly resize.

Note that calling toggle-frame-maximized after the startup works like a
charm.

I've tried patching src/nsterm.m file by chaning definition of
FRAME_DECORATED_FLAGS from

  #define FRAME_UNDECORATED_FLAGS NSWindowStyleMaskBorderless

to

  #define FRAME_UNDECORATED_FLAGS NSWindowStyleMaskBorderless |
   NSWindowStyleMaskResizable

and creating EmacsFSWindow instead of EmacsWindow (so canBecomeKeyWindow
and canBecomeMainWindow both return YES).

But it didn't make the trick.

Let me know if you need any additional information.

In GNU Emacs 26.1 (build 1, x86_64-apple-darwin14.5.0, NS appkit-1348.17
Version 10.10.5 (Build 14F2511))
of 2018-05-31 built on builder10-10.porkrind.org
Windowing system distributor 'Apple', version 10.3.1561
Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
user-error: Beginning of history; no preceding item
user-error: End of history; no default available

Configured using:
'configure --with-ns '--enable-locallisppath=/Library/Application
Support/Emacs/${version}/site-lisp:/Library/Application
Support/Emacs/site-lisp' --with-modules'

Configured features:
NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS MODULES THREADS

Important settings:
  value of $LANG: en_GB.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
  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
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny seq byte-opt gv
bytecomp byte-compile cconv cl-loaddefs cl-lib dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg
epg-config gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils thingatpt elec-pair
time-date tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/ns-win ns-win ucs-normalize mule-util
term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow isearch timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame 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 charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote kqueue cocoa ns multi-tty make-network-process emacs)

Memory information:
((conses 16 204085 7246)
(symbols 48 20096 1)
(miscs 40 44 157)
(strings 32 28985 1457)
(string-bytes 1 764133)
(vectors 16 35057)
(vector-slots 8 713646 16946)
(floats 8 49 67)
(intervals 56 197 0)
(buffers 992 11))


Best regards,
Boris