Modus themes 1.6.0 for GNU Emacs

Just published version 1.6.0 of the Modus themes. The detailed release notes are reproduced below.

For any questions pertaining to this publication, feel welcome to contact me.

I will now prepare the patch for emacs.git. The modus-themes package in GNU ELPA fetches its contents from emacs.git, so expect an update shortly thereafter.

Modus themes version 1.6.0

By Protesilaos Stavrou info@protesilaos.com on 2021-09-29

This entry records the changes made to the project since the release of version 1.5.0 on 2021-07-15. There have been around 70 commits since then.

Every colour-related modification referenced herein is always implemented in accordance with the primary 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). Such edits also account for colour-coding that is optimised for the needs of users with red-green colour deficiency (deuteranopia or variants).

Here is the URL of the manual: https://protesilaos.com/emacs/modus-themes. Or read it from Emacs by evaluating this form:

(info "(modus-themes) Top")

The themes are built into Emacs version 28 (current development target), and are available on GNU ELPA as well as other archives. This release is the final one for the emacs-28 branch, as that gets cut as the next stable release of GNU Emacs. Future releases will target Emacs 29 once that becomes the new master branch.

Customisation options

[ Themes need to be reloaded for changes to take effect. ]

Introduced the new modus-themes-tabs-accented boolean option. When set to non-nil, it renders the background of all tab interfaces in a shade of blue. Those interfaces are tab-bar (built-in), tab-line (built-in), and Centaur tabs.
- The background “accented” colour is the same as the one used for mode lines when modus-themes-mode-line is configured accordingly.
Tweaked the modus-themes-mode-line to accept a padded symbol as part of the list of properties it can read. This will increase the spacing around the mode lines’ text, making the line taller overall but also more spacious.

Thanks to Manuel Uberti for making the proposal and providing feedback in issue 228: https://gitlab.com/protesilaos/modus-themes/-/issues/228.
Added the modus-themes-scale-small which complements the existing scale values with one that is meant to be smaller than the base height. This option is reserved for special cases and is currently only used as an opt-in feature in the Org agenda.
Expanded the modus-themes-org-agenda with more parameters:
- The current date can now also be underlined.
- Date headings can be scaled/enlarged in size.
- Events, like those of the Diary or sexp entries, can be customised.
Consult the manual or the variable’s doc string for the details.
Removed the obsoleted aliases modus-themes-slanted-constructs and modus-themes-scale-5. Those are superseded by the more appropriately named modus-themes-italic-constructs and modus-themes-scale-title.

Thanks to Nicolas De Jaeghere for the patch in merge request 47: https://gitlab.com/protesilaos/modus-themes/-/merge_requests/47.

Faces and face groups

Make the prodigy faces for red/green/yellow inherit from the faces error/success/warning, respectively. This is done to (i) avoid duplication and (ii) ensure that the green/success colour coding is consistent with the goal of the themes to empower users with red-green colour deficiency. The boolean option that changes all such greens to shades of blue is modus-themes-success-deuteranopia.
Assigned the :extend attribute to the org-code face. This is necessary when the Org source contains lines that start with a colon sign. Those are interpreted as code blocks. For example:
```
# Sample code block
:  #+BEGIN_SRC emacs-lisp
:    (defun in-interval (bounds el)
:      (and (>= el (car bounds)) (<= el (cadr bounds))))
:  #+END_SRC
```
With the :extend in place, the background stretches to the edge of the window, thus giving those lines a uniform rectangular shape. For inline uses of org-code, the background should remain limited to the span of the text.
Broadened support for marginalia faces in two phases.
- The first pertained to the file permissions that are shown when completing against file paths. Their style is similar to what dired+ or the direfl packages provide, however we have taken care to optimise the interface for the purposes of completion UIs—where things can look like Dired, we make them alike, but where they must differ, we differentiate the designs accordingly. There can be no compromises or arbitrary constraints.
  
  Also read: https://github.com/minad/marginalia/pull/91.
- The second batch covered all sorts of extra classes that provide granular control over the appearance of Marginalia instances. Refinements also had to be made to already-supported faces for the sake of achieving consistency across the various Marginalia interfaces.
  
  Also read: https://github.com/minad/marginalia/pull/92.
Refined diredfl and dired+ faces. For the various “priv” faces, the intent is to increase the difference in hueness between adjacent file permissions (the changes are minor, but they do change the overall result). Numbers are toned down so that they do not clash with dates. The file suffix no longer uses cyan to stand out more in detailed views.
Made icomplete-selected-match (Emacs28) more legible by aligning its presentation with metaphors that are estaslished across the modus-themes. Thanks to Kévin Le Gouguec (peniblec) for noting the inconsistency with the new face upstream and for writing the patch for it in merge request 50: https://gitlab.com/protesilaos/modus-themes/-/merge_requests/50. Also thanks to Manuel Uberti for confirming that things would look consistent in the comments’ section of that merge request.
Fixed faulty inheritance for the web-mode-keyword-face. It should now properly copy the attributes of font-lock-keyword-face.
Made inheritance of the new help-key-binding (Emacs28 key) the default for all faces that need to style key bindings.

In Emacs 28 all key bindings are automatically displayed with the face help-key-binding which uses some new face attributes to draw a cleaner box around it. Given that the themes must work with earlier versions of Emacs, we cannot inherit it unconditionally so we added the relevant conditionality. It is nice to offer this feature to those who use the themes on Emacs 28. Older versions retain the previous style of a blue colour coupled with a bold weight.

The exception to this rule is the transient.el faces (this is the pop-up window used by Magit, among others—transient.el is now built into Emacs). The box effect creates unpredictable misalignments, so we default to the old key binding style for those.

Thanks to Manuel Uberti and Kevin Fleming for their feedback in issue 232: https://gitlab.com/protesilaos/modus-themes/-/issues/232.
Added support for the new notmuch-jump-key face. I contributed this face in commits c37c9912, 5cc106b0 to the Notmuch git repo: https://git.notmuchmail.org/git/notmuch.
Updated the bookmark-face (Emacs28) as it has been changed upstream to be a fringe indicator instead of an in-buffer, line-wide background highlight.

Aligned Ediff faces with other modus-themes-diffs styles. Before we would differentiate a “focus state”, though that is now considered surplus to requirements. The notion of a “focus state” only make sense in Magit which applies variegated colour-coding to diff hunks based on their state. Whereas non-active Ediff changes are grayed out, so there is no need for further colour-coding nuances. The most noticeable change is with:

(setq modus-themes-diffs 'bg-only)

As noted in the commit message of 64c74ae (from 2021-09-04):

If users think this change is for the worse, we can always define a
helper function like this:

    (defun modus-themes--ediff-style (bgonly default)
      "Diff style for Ediff.
    BGONLY and DEFAULT depend on the value of `modus-themes-diffs'.
    The former is more subtle."
      (if (eq modus-themes-diffs 'bg-only)
          (list bgonly)
        (list default)))

And apply it thus:

    `(ediff-current-diff-A ((,class :inherit ,@(modus-themes--ediff-style
                                                'modus-themes-diff-removed
                                                'modus-themes-diff-focus-removed))))

No feedback was received towards that end in about a month, so we consider the change to be acceptable, without prejudice to the possibility of future updates.

Unified the styles of org-agenda-calendar-sexp, org-agenda-diary, and org-agenda-calendar-event. This is not a user-facing change but an internal refactoring to avoid repetition. It also makes things easier for the implementation of the modus-themes-org-agenda (as mentioned above).
Ensured that the bookmark-menu-bookmark face inherits from the bold face. By default it hardcodes the bold weight, whereas we instruct it to inherit the bold face. A user can thus change the :weight of that face to whatever they want, like semibold, extrabold, etc. We do this throughout the themes for bold and italics—consider it a “hidden feature” of sorts. Check the manual for more on the matter:
```
(info "(modus-themes) Configure bold and italic faces (DIY)")
```
Provided support for tab-bar groups (Emacs28). Specifically the faces tab-bar-tab-group-current and tab-bar-tab-group-inactive.

Thanks to Adam Porter (alphapapa) for the feedback in issue 8 over at the Github mirror: https://github.com/protesilaos/modus-themes/issues/8.
Decoupled the stripes face from that of hl-line-face. This is because the stripes are not meant to change depending on the value of the user option modus-themes-hl-line.
Revised the red shade of “flagged” entries in mu4e and notmuch. Those are now consistent with Gnus. The shade of red that was used before was closer to the orange side of the spectrum whereas the current has hints of blue (a cherry colour) and thus combines better with the cyan and blue that prevail in those interfaces. These are fine margins, though the effect is noticeable regardless.
Configured the new ansi-color faces (Emacs28) which are used by shells and terminals (among others). Thanks to Manuel Uberti for reporting the changes to upstream Emacs in issue 236: https://gitlab.com/protesilaos/modus-themes/-/issues/236.
Expanded support for EMMS faces, pertaining to its browser views. Thanks to Feng Shu (tumashu) for bringing those to my attention in issue 11 over at the Github mirror: https://github.com/protesilaos/modus-themes/issues/11.
Styled the new tab-line-tab-modified face (Emacs28). It should now use a faint red colour to denote changes to the underlying file. Thanks to Adam Porter (alphapapa) for bringing it to my attention in issue 12 over at the Github mirror: https://github.com/protesilaos/modus-themes/issues/12.
Configured the single face that the cursor-flash package has to offer. Thanks to Manuel Uberti for the feedback in issue 231: https://gitlab.com/protesilaos/modus-themes/-/issues/231.
Included elpher in the list of supported packages by means of covering the heading faces it implements.
Recalibrated certain dedicated colours for inactive tabs and tweaked tab faces to (i) marginally improve the default aesthetic and (ii) harmonise it with the style of modus-themes-tabs-accented.
Removed the foreground attribute from all markup faces that are meant to denote emphasis in italics. That is because such faces are typically composed with others, so we do not wish to inadvertently override any other colour that would otherwise have taken effect.

Wrote the faces for upstream Org that improve the contextuality of various agenda views (included in version 9.5). This was done in close collaboration with Gustavo Barros who offered detailed feedback in issue 208 (which also led to the creation and eventual expansion of the modus-themes-org-agenda user option): https://gitlab.com/protesilaos/modus-themes/-/issues/208.

Four new faces improve certain styles and offer more flexibility for some Org agenda views: org-agenda-date-weekend-today, org-imminent-deadline, org-agenda-structure-secondary, org-agenda-structure-filter. They inherit from existing faces in order to remain backward-compatible.

Quoting from https://list.orgmode.org/87lf7q7gpq.fsf@protesilaos.com/:

+ The 'org-imminent-deadline' is useful to disambiguate generic
  warnings from deadlines.  For example, a warning could be
  rendered in a yellow colored text and have a bold weight,
  whereas a deadline might be red and styled with italics.

+ The 'org-agenda-structure-filter' applies to all tag/term
  filters in agenda views that search for keywords or patterns.
  It is designed to inherit from 'org-agenda-structure' in
  addition to the 'org-warning' face that was present before (and
  removes the generic 'warning' face from one place).  This offers
  the benefit of consistency, as, say, an increase in font height
  or a change in font family in 'org-agenda-structure' will
  propagate to the filter as well.  The whole header line thus
  looks part of a singular design.

+ The 'org-agenda-structure-secondary' complements the above for
  those same views where a description follows the header.  For
  instance, the tags view provides information to "Press N r" to
  filter by a numbered tag.  Themes/users may prefer to
  disambiguate this line from the header above it, such as by
  using a less intense color or by reducing its height relative to
  the 'org-agenda-structure'.

+ The 'org-agenda-date-weekend-today' provides the option to
  differentiate the current date on a weekend from the current
  date on weekdays.

Other patches I have made to, inter alia, emacs.git and org.git with regard to faces are documented in previous change log entries.

Documentation

Removed references to old versions of the themes from before their refactoring in version 1.0.0. Those old packages no longer exist. Users must install the modus-themes and then load either of modus-operandi or modus-vivendi.
Included various extensions of the Vertico package in the list of indirectly supported packages. Those define faces which either inherit from basic ones that we already support or use colours that are consistent with our accessibility target.
Referenced side-hustle, tide, bufler as an indirectly supported packages for the same reasons.
Simplified time-stamp local variables that are used in modus-themes.el to show the time the file was edited. We apply time-stamp-pattern instead of setting multiple time-stamp variables. Thanks to Stephen Gildea for the patch, which was sent to me via email (yes, you can always do that).
Updated the manual’s “acknowledgements” section to name all new contributors to code/ideas/feedback.
Furnished information on how to configure the highlight-parentheses package and extend its faces for use with the themes. The entry provides a complete Elisp implementation.
Improved the code samples for the prism.el setup that users may wish to set up by themselves. The new lists of colours work better when Prism’s colouration is limited to a small set of hues.
Deleted trailing whitespace in the manual which had adverse effects when trying to compile the modus-themes.org over at emacs.git. Thanks to Philip Kaludercic for the patch in merge request 49: https://gitlab.com/protesilaos/modus-themes/-/merge_requests/49.

Thanks again to everyone involved. Looking forward to see the Modus themes, version 1.6.0, as part of the next stable release of Emacs.