Set mwheel default scroll value to 1 (bug#43380)

* lisp/mwheel.el (mouse-wheel-scroll-amount): Change default value 5 to 1
and shift default value from 1 to 5.
Default value is changed as discussed in etc/TODO.

3 files changed, 8 insertions, 7 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 5cb31256ff4..6a7c99f48d5 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -135,6 +135,10 @@ and mode line.  ('mwheel-mode' is enabled by default on most graphical
 displays.)
 
 ---
+** Mouse wheel scrolling now defaults to one line at a time.
+Old default of five lines at a time is now bound to Shift modifier.
+
+---
 ** The default value of 'frame-title-format' and 'icon-title-format' has changed.
 These variables are used to display the title bar of visible frames
 and the title bar of an iconified frame.  They now show the name of
diff --git a/etc/TODO b/etc/TODO
index 152a29964f3..b445b673607 100644
--- a/etc/TODO
+++ b/etc/TODO
@@ -924,17 +924,14 @@ features of that interface could be implemented NS.
 
 **** Smooth scrolling -- maybe not a good idea
 Today, by default, scrolling with a trackpad makes the text move in
-steps of five lines.  (Scrolling with SHIFT scrolls one line at a time.)
+steps of one line.  (Scrolling with SHIFT scrolls five lines at a time.)
 
 The "mac" port provides smooth, pixel-based, scrolling.  This is a very
-popular features.  However, there are drawbacks to this method: what
+popular feature.  However, there are drawbacks to this method: what
 happens if only a fraction of a line is visible at the top of a
 window, is the partially visible text considered part of the window or
 not?  (Technically, what should 'window-start' return.)
 
-An alternative would be to make one-line scrolling the default on NS
-(or in Emacs in general).
-
 Note: This feature might not be allowed to be implemented until also
 implemented in Emacs for a free system.
 
diff --git a/lisp/mwheel.el b/lisp/mwheel.el
index 32fde0dd058..0100b8de81e 100644
--- a/lisp/mwheel.el
+++ b/lisp/mwheel.el
@@ -85,7 +85,7 @@ set to the event sent when clicking on the mouse wheel button."
   :type 'number)
 
 (defcustom mouse-wheel-scroll-amount
-  '(5 ((shift) . 1) ((meta) . nil) ((control) . text-scale))
+  '(1 ((shift) . 5) ((meta) . nil) ((control) . text-scale))
   "Amount to scroll windows by when spinning the mouse wheel.
 This is an alist mapping the modifier key to the amount to scroll when
 the wheel is moved with the modifier key depressed.
@@ -125,7 +125,7 @@ scrolling."
                     (float :tag "Scroll fraction of window")
                     (const :tag "Change face size" :value text-scale)))))
   :set 'mouse-wheel-change-button
-  :version "27.1")
+  :version "28.1")
 
 (defcustom mouse-wheel-progressive-speed t
   "If non-nil, the faster the user moves the wheel, the faster the scrolling.