In follow mode, prevent the cursor resting on a partially displayed line

Don't merge to master.  This fixes bug #32848

* lisp/follow.el (follow-adjust-window): If point ends up in a partially
displayed line in a left hand or middle window, move it one line
forward, to
prevent unwanted scrolling should make-cursor-line-fully-visible be
non-nil.

1 files changed, 7 insertions, 1 deletions

diff --git a/lisp/follow.el b/lisp/follow.el
index fd397c077bb..eb48ec179cf 100644
--- a/lisp/follow.el
+++ b/lisp/follow.el
@@ -1385,7 +1385,13 @@ non-first windows in Follow mode."
           (unless (eq win (selected-window))
             (let ((p (window-point win)))
               (set-window-start win (window-start win) nil)
-              (set-window-point win p))))
+              (if (nth 2 (pos-visible-in-window-p p win t))
+                  ;; p is in a partially visible line.  We can't leave
+                  ;; window-point there, because C-x o back into WIN
+                  ;; would then fail.
+                  (with-selected-window win
+                    (forward-line)) ; redisplay will recenter it in WIN.
+                (set-window-point win p)))))
 
         (unless visible
           ;; If point may not be visible in the selected window,