Modus themes 1.3.0 for GNU Emacs

Just published version 1.3.0 of the Modus themes. The detailed release notes are reproduced below. For any questions pertaining to this publication feel welcome to contact me.

My immediate task now is to prepare patches for upstream Emacs (Emacs28). GNU ELPA syncs directly from emacs.git, so expect an update shortly thereafter.


Modus themes version 1.3.0

By Protesilaos Stavrou <info@protesilaos.com> on 2021-04-17

This entry records the changes introduced to the project since the
publication of version 1.2.0 (2021-03-04).  There have been around 100
commits in the meantime, as is the norm with all releases hitherto.

Every colour-related modification documented herein conforms with the
overarching accessibility objective of the themes for a minimum contrast
ratio of 7:1 between background and foreground values in their given
combination (the WCAG AAA standard).

As the official manual is referenced several times throughout this log,
make sure to store its URL: <https://protesilaos.com/modus-themes>.  Or
read it from Emacs' Info reader by evaluating this form:

    (info "(modus-themes) Top")

If you are coming from older versions, please consult the change log
entry for version 1.0.0 with regard to the breaking changes that were
introduced.

Remember that the themes are built into Emacs28, and are available on
GNU ELPA, as well as other archives.


Customisation options
---------------------

+ The old 'modus-themes-intense-hl-line' boolean variable has been
  replaced by 'modus-themes-hl-line', which provides several options for
  how to style the current line of 'hl-line-mode'.  To retain the old
  effect, one must do this:

      ;; Replacement for (setq modus-themes-intense-hl-line t)
      (setq modus-themes-hl-line 'intense-background)

  The list of possible values:

    1. nil (default)
    2. intense-background
    3. accented-background
    4. underline-neutral
    5. underline-accented
    6. underline-only-neutral
    7. underline-only-accented

  The doc string of 'modus-themes-hl-line' as well as the manual
  describe the specifics.  Thanks to Manuel Uberti for the feedback in
  commit b020592:
  <https://gitlab.com/protesilaos/modus-themes/-/commit/b020592e1a96d6e00d7d03faf9c293ec6081d49c>.

+ The 'modus-themes-mode-line' variable now accepts three new "accented"
  styles that complement the existing set:

    1. nil (default)
    2. 3d
    3. moody
    4. borderless
    5. borderless-3d
    6. borderless-moody
    7. accented
    8. accented-3d
    9. accented-moody

+ The 'modus-themes-region' is extended with two new options of an
  "accent" background:

    1. nil (default)
    2. no-extend
    3. bg-only
    4. bg-only-no-extend
    5. accent
    6. accent-no-extend

+ The default value of 'modus-themes-headings' for per-level styles can
  now be set to nil.  This fixes an inconsistency between the fallback
  value, which accepted nil, and the per-level styles which did not.
  Thanks to Mauro Aranda for reporting this in issue 163:
  <https://gitlab.com/protesilaos/modus-themes/-/issues/163>.

  Please read the manual for the specifics of this variable, as it is an
  alist that accepts several possible combinations.


Updates to the manual
---------------------

+ Rewrote the sections that cover the aforementioned customisation
  options.

  - For 'modus-themes-mode-line', we had to revise the recommendation
    for setting 'face-near-same-color-threshold' to 45000.  That value
    is appropriate for the 'moody' and 'borderless-moody' options.
    Whereas for 'accented-moody' the number should be raised to 70000.
    Thanks to Nicolas De Jaeghere for providing this piece of
    information:
    <https://gitlab.com/protesilaos/modus-themes/-/commit/ab6ba698269f012ec880b690282264649bfb3b0d#note_551342198>

+ Rephrased the GNU Free Documentation License quote to match the style
  of other manuals that are also built into Emacs.

+ Documented 'org-mode' variables that affect the looks of various
  fontification styles.

+ Simplified the 'kbd' macro that is declared in modus-themes.org to
  allow GNU ELPA's build system to parse the file for Emacs 26.

+ Documented existing support for 'tab-bar-mode' and 'tab-line-mode'.

+ Wrote a note on how to configure the 'dimmer.el' library by Neil
  Okamoto, in order to guarantee consistent results with the themes.
  The key is to use the RGB colour space instead of CIELAB.

+ Included note on shr.el fonts and how those are used by EWW and
  Elfeed.

+ Added a "Do-It-Yourself" (DIY) section on how to remap buffer-local
  faces.

+ Detailed a DIY method to make the buffer-local backdrop of a pdf-tools
  page use a distinct colour than the default white for Modus Operandi.
  Extended the same principle to Modus Vivendi and described how to
  adapt to theme changes (such as via 'modus-themes-toggle').  Thanks to
  Utkarsh Singh for providing feedback on this topic in issue 175:
  <https://gitlab.com/protesilaos/modus-themes/-/issues/175>.

+ Elaborated on DIY techniques to programmatically override the
  saturation of all colours specified by the active Modus theme.  Thanks
  to user pRot0ta1p for the feedback in issue 166:
  <https://gitlab.com/protesilaos/modus-themes/-/issues/166>.


Support for packages
--------------------

These are added to the already comprehensive list of explicitly
supported packages:

+ corfu
+ embark

+ pandoc-mode.  Thanks to Farasha Euker for the feedback in issue 171:
  <https://gitlab.com/protesilaos/modus-themes/-/issues/171>.

+ tab-bar-groups
+ telega
+ vertico

Also added support for the 'help-key-binding' face which is part of
Emacs 28.


Changes to already supported faces or face groups
-------------------------------------------------

+ Renamed all internal faces that the themes defined from
  "modus-theme-*" to "modus-themes-*".

+ Refashioned all Ediff faces in the process of a major review of this
  tools' overall design.  The manifold changes are:

  - All inactive diffs respect the underlying fontification
    (e.g. programming syntax highlighting).  Before they would override
    it with a gray foreground.

  - All inactive diffs have been toned down, as their background is a
    finer shade of gray than the prominent one that was used before.

  - There no longer is a visual distinction between even and odd
    inactive diffs (by means of different shades of gray).  We are of
    the opinion that such subtleties, whose utility is marginal at best,
    have no place in themes that are designed for accessibility.

  - All bespoke gray colour combinations that were only intended for
    those inactive diffs have thus been removed from each theme's
    palette.

  - Active diffs follow the same style as diff-mode, to ensure
    theme-wide consistency (all diff styles are controlled by the
    variable 'modus-themes-diffs').
  
  This topic was discussed at length (with screenshots) in issue 169:
  <https://gitlab.com/protesilaos/modus-themes/-/issues/169>.  Thanks to
  peniblec and Nicolas De Jaeghere for their feedback.

+ Made 'smerge-markers' and 'vdiff-closed-fold-face' look like the
  headings in 'diff-mode' in the interest of consistency, especially
  while configuring the 'modus-themes-diffs' variable.

+ Ensured consistency between all faces that pertain to key bindings in
  contexts where the hint to the key is active, in that pressing the key
  performs the action (e.g. Magit's transient buffers, which-key,...).
  The 'help-key-binding' for Emacs 28 is not included in this group,
  because it applies in cases where the keys are not active, such as in
  Help buffers.

+ Refined 'epa-validity-disabled' and 'epa-validity-high' faces.  The
  former no longer uses a background, as that was considered an
  exaggeration.  While the latter is cast in a cyan hue instead of green
  for greater clarity (this relates to the general push to optimise for
  red-green colour deficiency, which means to only use green where it is
  absolutely necessary and, in such cases, to provide for a blue-ish
  alternative, as with the 'deuteranopia' value that can be assigned to
  'modus-themes-diffs').

+ Reworked 'ace-window', 'avy', and 'magit-blame' faces to ensure that
  their overlays do not inherit the face properties of underlying text,
  such as a different font family or height.  Thanks to Nicolas De
  Jaeghere for the multiple merge requests and the concomitant feedback:

  - <https://gitlab.com/protesilaos/modus-themes/-/merge_requests/27>.
  - <https://gitlab.com/protesilaos/modus-themes/-/merge_requests/29>.
  - <https://gitlab.com/protesilaos/modus-themes/-/merge_requests/30>.
  - <https://gitlab.com/protesilaos/modus-themes/-/merge_requests/31>.
  - <https://gitlab.com/protesilaos/modus-themes/-/merge_requests/32>.

  Also thanks to Damien Cassou for reporting an intermediate problem
  with 'avy' in issue 177; a problem that was eventually addressed by
  Nicolas De Jaeghere in merge request 31 (cited above):
  <https://gitlab.com/protesilaos/modus-themes/-/issues/177>.

+ Optimised the colour combinations used by 'avy' to improve the
  distinction between consecutive characters.

+ Reduced the brightness of EWW certificate faces, as they would attract
  disproportionate attention to themselves.

+ Reworked all EWW text field and button faces to look more like what
  they are supposed to.

+ Removed the slant and distinct foreground from the 'org-quote' face,
  as they would interfere with emphasis within the quote block.  Thanks
  to Farasha Euker for the feedback in issue 171:
  <https://gitlab.com/protesilaos/modus-themes/-/issues/171>.

+ Reduced the intensity in colouration of 'org-code' and 'org-macro' in
  order to avoid exaggerations and prevent their compounding effect in
  technical documents that include a high concentration of those faces.
  They still retain their overall character and continue to look like
  variants of 'org-verbatim'.

+ Extended support for Selectrum's new 'selectrum-quick-keys-highlight'
  and 'selectrum-quick-keys-match'.

+ Adjusted a few bongo faces for improved consistency and a more
  pleasant result overall.  Quote from commit 07224cda08:

      Refine bongo faces for consistency

      The previous design was meant to keep the track fields distinct
      from each other.  However the use of yellow was not good
      aesthetically: it does not fit with the rest of the theme.

      Upon further experimentation, I realised that the album field
      (yellow) is only present when the artist and title fields are also
      available: first is the title, then the artist, and finally the
      album.  This is true even with 'bongo-join-inserted-tracks' set to
      a non-nil value.  So changing the face from yellow to a neutral
      value is safe.

      The other two faces are adapted to look better in the new context.

+ Made more command prompt faces respond to changes in the variable
  'modus-themes-prompts'.  This concerns faces from the groups cider,
  circe, erc, indium, rcirc.

+ Refashioned typescript faces, making them more prominent by default,
  while also exposing them to the value of 'modus-themes-syntax'.

+ Revised the style of 'info-colors-ref-item-command'.  This makes
  commands look the same as functions, which is technically correct.  It
  also predicates the exact style on the value of the variable
  'modus-themes-syntax'.

+ Made all enh-ruby-mode faces adapt to 'modus-themes-syntax'.  Same for
  julia.

+ Reconfigured all ztree faces for stylistic consistency.  The
  'ztreep-diff-model-add-face' now responds to the 'deuteranopia' value
  that can be passed to 'modus-themes-diffs'.

+ Appended the ':extend t' attribute to 'gnus-summary-cancelled' and
  'gnus-summary-selected'.  These are only noticeable on Emacs 28
  following commit 88409b21c2 in emacs.git.

+ Tweaked all faces of 'highlight-changes-mode' to better deliver on the
  intent of that mode.

+ Opted to unconditionally render all 'dired-async' faces in a bold
  typographic weight, instead of basing them on a non-nil value for
  'modus-themes-bold-constructs'.  Also changed 'dired-async-message' to
  a blue foreground, which further improves the themes' performance for
  red-green colour deficiency.

+ Adjusted the colours of some 'notmuch-crypto-*' faces to better convey
  their meaning.

+ Removed remaining conditional logic for underline styles in some
  spell- and linter- related faces to ensure that all such cases are
  controlled by the variable 'modus-themes-lang-checkers' (building on
  work that had been done in the past).

+ Stopped changing 'keycast-key' to match the modeline style, as that
  diluted the meaning of the variable 'modus-themes-mode-line'.

+ Tweaked calendar and diary faces for stylistic effect, except for the
  'diary' face which has been converted from a green to a blue variant
  for the purposes of coping with cases of red-green colour deficiency.


Miscellaneous
-------------

+ Clarified the changes in the backward-incompatible transition from
  version 0.13.0 of the themes to >= 1.0.0.  Thanks to Damien Cassou for
  reporting the absence of easy-to-find information in issue 174:
  <https://gitlab.com/protesilaos/modus-themes/-/issues/174>.

+ There were three point releases after 1.2.0 which refined certain
  aspects of the themes' packaging so that they could work both as
  built-in themes for Emacs as well as in package format via the likes
  of GNU ELPA.  Those issues were eventually resolved by Basil
  L. Contovounesios:

  - Issue 162: <https://gitlab.com/protesilaos/modus-themes/-/issues/162>.
  - Emacs bug#45068: <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=45068#218>.

+ Rewrote the 'modus-themes-headings' variable's declaration to improve
  its presentation in Custom interfaces.  Thanks to Mauro Aranda for
  submitting the patch for commit 1c60927ebd.

+ Applied the ':format' keyword to all 'defcustom' forms, based on the
  aforementioned patch.  This should make all options look better in the
  various Custom interfaces.  Thanks to Mauro Aranda for the feedback in
  issue 163: <https://gitlab.com/protesilaos/modus-themes/-/issues/163>.

+ Refined the colour values 'bg-alt' and 'bg-dim' in 'modus-vivendi' to
  improve their instantiation on Textual User Interfaces.  In
  particular, recalibrated the blue channel of light so that when the
  TUI cannot render the colour directly, it defaults to a gray value
  instead of a dark blue.

+ Added a "Last-Modified" meta header to modus-themes.el, with gets
  updated automatically and uses a timestamp.  This helps users who
  track the themes' git repo directly.  Thanks to Togan Muftuoglu for
  the feedback in issue 168:
  <https://gitlab.com/protesilaos/modus-themes/-/issues/168>.

+ Expanded the palette of each theme with accent values that are
  reserved for use in the tab-bar.  Those are used by the newly
  supported 'tab-bar-groups' package.

+ Recalibrated a few colour combinations to improve their resulting
  legibility.  The changes should not be noticeable to the untrained
  eye.  Interested parties can consult commit 349ea4a943.

+ Tweaked the hueness of the 'yellow-active' colour of 'modus-operandi'.

Thanks once again to everyone involved!