22 files changed, 180 insertions, 1 deletions
diff --git a/README.org b/README.org
index a9c0517..b1963e8 100644
--- a/README.org
+++ b/README.org
@@ -368,6 +368,47 @@ will retain the original aesthetic for that level.  For example:
         (t . t))) ; default style for all other levels
 #+end_src
 
+** Style of region highlight
+:PROPERTIES:
+:CUSTOM_ID: h:1d5fa3d8-a769-455a-aac7-5c1b925bb10b
+:END:
+
+[ This user option is part of {{{development-version}}}. ]
+
+#+vindex: ef-themes-region
+The user option ~ef-themes-region~ controls the appearance of the
+~region~ face (the highlighted selection of an area).
+
+The value it accepts is a list of symbols.
+
+If ~nil~ or an empty list (the default), use a subtle background for
+the region and preserve the color of selected text.
+
+The ~no-extend~ symbol limits the highlighted area to the end of the
+line, so that it does not reach the edge of the window.
+
+The ~neutral~ symbol makes the highlighted area's background gray (or
+more gray, depending on the theme).
+
+The ~intense~ symbol amplifies the intensity of the highlighted area's
+background color.  It also overrides any text color to keep it
+legible.
+
+Combinations of those symbols are expressed in any order.
+
+In user configuration files the form may look like this:
+
+#+begin_src emacs-lisp
+(setq modus-themes-region '(intense no-extend))
+#+end_src
+
+Other examples:
+
+#+begin_src emacs-lisp
+(setq modus-themes-region '(intense))
+(setq modus-themes-region '(intense no-extend neutral))
+#+end_src
+
 * Loading a theme
 :PROPERTIES:
 :CUSTOM_ID: h:75d74aea-d17f-497f-a3b8-f0bf4c372de0
diff --git a/ef-autumn-theme.el b/ef-autumn-theme.el
index bd1ac9f..8c8b88a 100644
--- a/ef-autumn-theme.el
+++ b/ef-autumn-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#c0b000")
       (underline-info    "#22b022")
 
+      ;; Conditional hues
+      (bg-region-intense "#4f4400")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow)
diff --git a/ef-bio-theme.el b/ef-bio-theme.el
index d79de33..e172d1d 100644
--- a/ef-bio-theme.el
+++ b/ef-bio-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#c0b000")
       (underline-info    "#22b022")
 
+      ;; Conditional hues
+      (bg-region-intense "#0f5450")
+
       ;; Mappings
       (err red)
       (warning yellow-cooler)
diff --git a/ef-cherie-theme.el b/ef-cherie-theme.el
index 088dc1e..dcc3198 100644
--- a/ef-cherie-theme.el
+++ b/ef-cherie-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#c0b000")
       (underline-info    "#22b022")
 
+      ;; Conditional hues
+      (bg-region-intense "#3f3460")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow-warmer)
diff --git a/ef-cyprus-theme.el b/ef-cyprus-theme.el
index b10da96..83d9aaa 100644
--- a/ef-cyprus-theme.el
+++ b/ef-cyprus-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#bf5f00")
       (underline-info    "#02af5f")
 
+      ;; Conditional hues
+      (bg-region-intense "#dcd09f")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow)
diff --git a/ef-dark-theme.el b/ef-dark-theme.el
index 13ba89c..0775bc1 100644
--- a/ef-dark-theme.el
+++ b/ef-dark-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#c0b000")
       (underline-info    "#22b022")
 
+      ;; Conditional hues
+      (bg-region-intense "#3a3465")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow)
diff --git a/ef-day-theme.el b/ef-day-theme.el
index cf69ece..50f8d0f 100644
--- a/ef-day-theme.el
+++ b/ef-day-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#bf5f00")
       (underline-info    "#02af52")
 
+      ;; Conditional hues
+      (bg-region-intense "#dfc39a")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow)
diff --git a/ef-deuteranopia-dark-theme.el b/ef-deuteranopia-dark-theme.el
index 0f8402a..1695b95 100644
--- a/ef-deuteranopia-dark-theme.el
+++ b/ef-deuteranopia-dark-theme.el
@@ -147,6 +147,9 @@
       (underline-warning "#bfaf50")
       (underline-info    "#22cff2")
 
+      ;; Conditional hues
+      (bg-region-intense "#1f1f70")
+
       ;; Mappings
       (err yellow-warmer)
       (warning yellow)
diff --git a/ef-deuteranopia-light-theme.el b/ef-deuteranopia-light-theme.el
index 8da64e6..a0c944f 100644
--- a/ef-deuteranopia-light-theme.el
+++ b/ef-deuteranopia-light-theme.el
@@ -147,6 +147,9 @@
       (underline-warning "#6f3f00")
       (underline-info    "#025f92")
 
+      ;; Conditional hues
+      (bg-region-intense "#cfcf9a")
+
       ;; Mappings
       (err yellow-warmer)
       (warning yellow)
diff --git a/ef-duo-dark-theme.el b/ef-duo-dark-theme.el
index 15507e6..1ef3f80 100644
--- a/ef-duo-dark-theme.el
+++ b/ef-duo-dark-theme.el
@@ -147,6 +147,9 @@
       (underline-warning "#c0b000")
       (underline-info    "#22b022")
 
+      ;; Conditional hues
+      (bg-region-intense "#1f2f70")
+
       ;; Mappings
       (err red)
       (warning yellow)
diff --git a/ef-duo-light-theme.el b/ef-duo-light-theme.el
index 857466c..7412c42 100644
--- a/ef-duo-light-theme.el
+++ b/ef-duo-light-theme.el
@@ -148,6 +148,9 @@
       (underline-warning "#bf5f00")
       (underline-info    "#02af52")
 
+      ;; Conditional hues
+      (bg-region-intense "#dfc2b0")
+
       ;; Mappings
       (err red)
       (warning yellow)
diff --git a/ef-frost-theme.el b/ef-frost-theme.el
index f2bb3ce..b7d9fc3 100644
--- a/ef-frost-theme.el
+++ b/ef-frost-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#bf5f00")
       (underline-info    "#02af52")
 
+      ;; Conditional hues
+      (bg-region-intense "#aadfcc")
+
       ;; Mappings
       (err red)
       (warning yellow-cooler)
diff --git a/ef-light-theme.el b/ef-light-theme.el
index 117b735..adf7335 100644
--- a/ef-light-theme.el
+++ b/ef-light-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#bf5f00")
       (underline-info    "#02af52")
 
+      ;; Conditional hues
+      (bg-region-intense "#afdfc0")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow-warmer)
diff --git a/ef-night-theme.el b/ef-night-theme.el
index dcbfec1..285543b 100644
--- a/ef-night-theme.el
+++ b/ef-night-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#c0b000")
       (underline-info    "#22b022")
 
+      ;; Conditional hues
+      (bg-region-intense "#3f2f60")
+
       ;; Mappings
       (err red)
       (warning yellow-warmer)
diff --git a/ef-spring-theme.el b/ef-spring-theme.el
index 755b831..521d88c 100644
--- a/ef-spring-theme.el
+++ b/ef-spring-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#bf5f00")
       (underline-info    "#02af52")
 
+      ;; Conditional hues
+      (bg-region-intense "#dfb0d0")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow)
diff --git a/ef-summer-theme.el b/ef-summer-theme.el
index d4106df..5a5f6d5 100644
--- a/ef-summer-theme.el
+++ b/ef-summer-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#bf5f00")
       (underline-info    "#02af52")
 
+      ;; Conditional hues
+      (bg-region-intense "#caaadf")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow)
diff --git a/ef-themes.el b/ef-themes.el
index f38beae..c6e5ac1 100644
--- a/ef-themes.el
+++ b/ef-themes.el
@@ -256,8 +256,59 @@ ELPA (by Protesilaos))."
   :type 'boolean
   :link '(info-link "(ef-themes) UI typeface"))
 
+(defcustom ef-themes-region nil
+  "Control the appearance of the `region' face.
+
+The value is a list of symbols.
+
+If nil or an empty list (the default), use a subtle background
+for the region and preserve the color of selected text.
+
+The `no-extend' symbol limits the highlighted area to the end of
+the line, so that it does not reach the edge of the window.
+
+The `neutral' symbol makes the highlighted area's background
+gray (or more gray, depending on the theme).
+
+The `intense' symbol amplifies the intensity of the highlighted
+area's background color.  It also overrides any text color to
+keep it legible.
+
+Combinations of those symbols are expressed in any order.
+
+In user configuration files the form may look like this:
+
+    (setq modus-themes-region \\='(intense no-extend))
+
+Other examples:
+
+    (setq modus-themes-region \\='(intense))
+    (setq modus-themes-region \\='(intense no-extend neutral))"
+  :group 'ef-themes
+  :package-version '(ef-themes . "0.10.0")
+  :type '(set :tag "Properties" :greedy t
+              (const :tag "Do not extend to the edge of the window" no-extend)
+              (const :tag "More neutral/gray background" neutral)
+              (const :tag "More intense background (also override text color)" accented))
+  :link '(info-link "(ef-themes) Style of region highlight"))
+
 ;;; Helpers for user options
 
+(defun ef-themes--warn (option)
+  "Warn that OPTION has changed."
+  (prog1 nil
+    (display-warning
+     'ef-themes
+     (format "`%s' has changed; please read the updated documentation" option)
+     :warning)))
+
+(defun ef-themes--list-or-warn (option)
+  "Return list or nil value of OPTION, else `ef-themes--warn'."
+  (let* ((value (symbol-value option)))
+    (if (or (null value) (listp value))
+        value
+      (ef-themes--warn option))))
+
 (defun ef-themes--fixed-pitch ()
   "Conditional application of `fixed-pitch' inheritance."
   (when ef-themes-mixed-fonts
@@ -310,6 +361,33 @@ sequence given SEQ-PRED, using SEQ-DEFAULT as a fallback."
           :weight
           (or weight 'unspecified))))
 
+(defun ef-themes--region (bg bgneutral bgintense bgintenseneutral fgintense)
+  "Apply `ef-themes-region' styles.
+
+BG is the default background.  BGNEUTRAL is its gray counterpart.
+BGINTENSE is an amplified variant of BG, while BGINTENSENEUTRAL
+is a more intense neutral background.  FGINTENSE is the
+foreground that is used with any of the intense backgrounds."
+  (let ((properties (ef-themes--list-or-warn 'ef-themes-region)))
+    (list
+     :background
+     (cond
+      ((and (memq 'intense properties) (memq 'neutral properties))
+       bgintenseneutral)
+      ((memq 'intense properties)
+       bgintense)
+      ((memq 'neutral properties)
+       bgneutral)
+      (bg))
+     :foreground
+     (if (memq 'intense properties)
+         fgintense
+       'unspecified)
+     :extend
+     (if (memq 'no-extend properties)
+         nil
+       t))))
+
 ;;; Commands and their helper functions
 
 (defun ef-themes--list-enabled-themes ()
@@ -608,7 +686,7 @@ Helper function for `ef-themes-preview-colors'."
     `(cursor ((,c :background ,cursor)))
     `(default ((,c :background ,bg-main :foreground ,fg-main)))
     `(italic ((,c :slant italic)))
-    `(region ((,c :background ,bg-region)))
+    `(region ((,c ,@(ef-themes--region bg-region bg-alt bg-region-intense bg-active fg-intense))))
     `(vertical-border ((,c :foreground ,border)))
 ;;;;; all other basic faces
     `(button ((,c :foreground ,link :underline ,border)))
diff --git a/ef-trio-dark-theme.el b/ef-trio-dark-theme.el
index 8130121..ae0b9e6 100644
--- a/ef-trio-dark-theme.el
+++ b/ef-trio-dark-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#c0b000")
       (underline-info    "#22b022")
 
+      ;; Conditional hues
+      (bg-region-intense "#5d336c")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow)
diff --git a/ef-trio-light-theme.el b/ef-trio-light-theme.el
index 85c65dc..3e8e811 100644
--- a/ef-trio-light-theme.el
+++ b/ef-trio-light-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#bf5f00")
       (underline-info    "#02af52")
 
+      ;; Conditional hues
+      (bg-region-intense "#aacacf")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow-warmer)
diff --git a/ef-tritanopia-dark-theme.el b/ef-tritanopia-dark-theme.el
index c591f7c..7116cd9 100644
--- a/ef-tritanopia-dark-theme.el
+++ b/ef-tritanopia-dark-theme.el
@@ -147,6 +147,9 @@
       (underline-warning "#ffafa0")
       (underline-info    "#22ffd2")
 
+      ;; Conditional hues
+      (bg-region-intense "#5f303f")
+
       ;; Mappings
       (err red-warmer)
       (warning magenta)
diff --git a/ef-tritanopia-light-theme.el b/ef-tritanopia-light-theme.el
index 70e0ed8..a950840 100644
--- a/ef-tritanopia-light-theme.el
+++ b/ef-tritanopia-light-theme.el
@@ -147,6 +147,9 @@
       (underline-warning "#af7f90")
       (underline-info    "#22afc2")
 
+      ;; Conditional hues
+      (bg-region-intense "#dfa5a5")
+
       ;; Mappings
       (err red-warmer)
       (warning magenta)
diff --git a/ef-winter-theme.el b/ef-winter-theme.el
index a603411..5ef582b 100644
--- a/ef-winter-theme.el
+++ b/ef-winter-theme.el
@@ -144,6 +144,9 @@
       (underline-warning "#c0b000")
       (underline-info    "#22b022")
 
+      ;; Conditional hues
+      (bg-region-intense "#4f2f5d")
+
       ;; Mappings
       (err red-warmer)
       (warning yellow)