Knocking Them Dead Backstage.

The leading lady is hopeless. She's a bosomy redhead who can't remember her lines, and, rather than act, she just poses. The show's final number, ''Wide Open Spaces,'' is pedestrian, and the choreography is longer on energy than style. The Boston reviews are dreadful. Fortunately, this is ''Robbin' Hood!'' This comically imperfect show within a show is at the center of the Kander and Ebb musical ''Curtains,'' the Paper Mill Playhouse's current production. ''Curtains'' itself is, thank goodness, considerably better. [ABSTRACT FROM PUBLISHER]