master e449f62: Fix jittering when precision scrolling over images

[Po Lu]

branch: master
commit e449f62a79f9acafd0b29df63e1cc177689b4407
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Fix jittering when precision scrolling over images
    
    * lisp/pixel-scroll.el
    (pixel-scroll-precision-initial-velocity-factor): Default to
    nil.
    (pixel-scroll-precision-scroll-down-page): Always set window
    start.
---
 lisp/pixel-scroll.el | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/lisp/pixel-scroll.el b/lisp/pixel-scroll.el
index 7722984..2e09f9a 100644
--- a/lisp/pixel-scroll.el
+++ b/lisp/pixel-scroll.el
@@ -133,7 +133,7 @@ This is only effective if supported by your mouse or 
touchpad."
   :type 'float
   :version "29.1")
 
-(defcustom pixel-scroll-precision-large-scroll-height 70
+(defcustom pixel-scroll-precision-large-scroll-height nil
   "Pixels that must be scrolled before an animation is performed.
 Nil means to not interpolate such scrolls."
   :group 'mouse
@@ -441,14 +441,13 @@ the height of the current window."
         (set-window-vscroll nil (+ (window-vscroll nil t)
                                    delta)
                             t)
-      (unless (eq (window-start) desired-start)
-        (set-window-start nil (if (zerop (window-hscroll))
-                                  desired-start
-                                (save-excursion
-                                  (goto-char desired-start)
-                                  (beginning-of-visual-line)
-                                  (point)))
-                          t))
+      (set-window-start nil (if (zerop (window-hscroll))
+                                desired-start
+                              (save-excursion
+                                (goto-char desired-start)
+                                (beginning-of-visual-line)
+                                (point)))
+                        t)
       (set-window-vscroll nil desired-vscroll t))
     (if (and (or (< (point) next-pos))
              (let ((pos-visibility (pos-visible-in-window-p next-pos nil t)))