;; If meta-buf doesn't exist, it is created. In that case, id doesn't have a
;; parent meta-buf
;; Check if META-BUF exists before calling this function
-;; Optional MUST-REDRAW, if non-nil, would force redrawal of the whole meta
+;; Optional MUST-REDRAW, if non-nil, would force redrawing of the whole meta
;; buffer. Otherwise, it will just go over the buffer and update activity marks
;; and session status.
;; SESSION-NUMBER, if specified, says which session caused the update.