By default Emacs ring the bell to attract the user’s attention, this is annoying.
To get a visual signal instead, set visual-bell with t Emacs should flash the screen to represent a bell.
We can also customize ring-bell-function to just flash the modeline.
(defun +ring-bell-fn ()
"Blink the mode-line."
(let ((buf (current-buffer)))
(invert-face 'mode-line)
(run-with-timer 0.05 nil
(lambda ()
(with-current-buffer buf
(invert-face 'mode-line))))))
(setq ring-bell-function '+ring-bell-fn
visible-bell t)