bug#55299: 29.0.50; Bug with the mode-line and pixel-scroll-precision-mode

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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Konrad Podczeck <konrad.podczeck@univie.ac.at> writes:

> Make an init file just containing the lines:
>
> (pixel-scroll-precision-mode)
> (setq-default mode-line-format nil)
>  
> Open the app, and any file. Do C-x 2. If I scroll upwards in the
> inactive pane, using the mouse wheel, then pixel-scroll-precision-mode
> does not work.


I cannot reproduce this on GNU/Linux, but it sounds similar to a problem
others have reported on macOS that I could never reproduce.

This is not the final fix, but please see if the following code fixes
your problem:

diff --git a/lisp/pixel-scroll.el b/lisp/pixel-scroll.el
index b0fe2f56c0..a7cfda2491 100644
--- a/lisp/pixel-scroll.el
+++ b/lisp/pixel-scroll.el
@@ -685,6 +685,8 @@ pixel-scroll-precision
       (setq window (frame-selected-window window)))
     (if (and (nth 4 event))
         (let ((delta (round (cdr (nth 4 event)))))
+          (when (< delta 1.0)
+            (setq delta 1.0))
           (unless (zerop delta)
             (if (> (abs delta) (window-text-height window t))
                 (mwheel-scroll event nil)