;; the target buffer are marked automatically with colored overlays
;; (for non-color displays see below) giving you feedback over the
;; extents of the matched (sub) expressions. The (non-)validity is
-;; shown only in the modeline without throwing the errors at you. If
+;; shown only in the mode line without throwing the errors at you. If
;; you want to know the reason why RE Builder considers it as invalid
;; call `reb-force-update' ("\C-c\C-u") which should reveal the error.