Thanks,
Nordlöw
Some imagination please.
(defun flash-region (start end &optional window timeout face)
(with-selected-window (or window (selected-window))
(let ((ov (make-overlay start end)))
(overlay-put ov 'window (selected-window))
(overlay-put ov 'face (or face 'next-error))
(run-with-timer (or timeout 0.35) nil #'delete-overlay ov)
nil)))
-ap