Variable is read but never assigned ADD-FIRST / ADD-LAST methods

[stefandrissen]

DEFINE VARIABLE cfoo AS CHARACTER NO-UNDO
   VIEW-AS SELECTION-LIST INNER-LINES 5 INNER-CHARS 60.

DEFINE FRAME fr
   cfoo
   .

ENABLE ALL WITH FRAME fr.

cfoo:ADD-FIRST( "foo":u ).
cfoo:ADD-LAST( "bar":u ).

DO ON ENDKEY UNDO, LEAVE:
   WAIT-FOR CLOSE OF THIS-PROCEDURE.
END.

MESSAGE cfoo:SCREEN-VALUE VIEW-AS ALERT-BOX.