+(defun beacon--ov-put-after-string (overlay colors)
+ "Add an after-string property to OVERLAY.
+The property's value is a string of spaces with background
+COLORS applied to each one."
+ (if (not colors)
+ (delete-overlay overlay)
+ (overlay-put overlay 'beacon-colors colors)
+ (overlay-put overlay 'after-string
+ (propertize
+ (mapconcat (lambda (c) (propertize " " 'face (list :background c)))
+ colors
+ "")
+ 'cursor 1000))))
+
+(defun beacon--after-string-overlay (colors)
+ "Put an overlay at point with an after-string property.
+The property's value is a string of spaces with background
+COLORS applied to each one."
+ (let ((ov (make-overlay (point) (point)))
+ ;; The after-string must not be longer than the remaining columns from
+ ;; point to right window-end else it will be wrapped around (assuming
+ ;; truncate-lines is nil) introducing an ugly wrap-around for a
+ ;; fraction of a second.
+ (colors (seq-take colors (- (window-width) (current-column)))))
+ (beacon--ov-put-after-string ov colors)
+ (overlay-put ov 'beacon t)
+ (push ov beacon--ovs)))
+