FUNCTION N_Selected

;+
; NAME:
;	Number of Plots Selected
; PURPOSE:
;	Returns the number of plots selected.
; CALLING SEQUENCE:
;	nb = N_Selected()
;-
; MODIFICATION HISTORY:
;	Created by A.Csillaghy in May 91

  COMMON SelectionRetrieval, plotsSelected

  nEls = N_Elements( plotsSelected )
  IF  nEls EQ 0 THEN RETURN, -1 $
  ELSE IF plotsSelected(0) EQ '' THEN RETURN, 0 $
  ELSE RETURN, nEls
  
END