gistfile1.txt

(defun mouse-button-pressed-p ()
  "Return non-nil if last event is a mouse-button down event."
  (run-hooks 'mouse-leave-buffer-hook)
  (and (consp last-input-event)
       (string-match-p "down-mouse-" (format "%s" (car last-input-event)))))

(defun etc-maybe-recenter ()
  (unless (or
           ;; don't interfere with erc scroll-to-bottom
           (derived-mode-p 'erc-mode 'term-mode 'shell-mode 'eshell-mode)
           (not (eq (get-buffer-window (current-buffer) t) (selected-window)))
           (equal (window-point) (point-max))
           ;; (region-active-p) ;; old way
           (mouse-button-pressed-p) ;; new way
           )
    (recenter)))

(defvar etc-recenter-timer nil)
(progn
  (when etc-recenter-timer
    (cancel-timer etc-recenter-timer))
  (setq etc-recenter-timer nil)
  (setq etc-recenter-timer (run-with-idle-timer 0.25 t #'etc-maybe-recenter)))