%N bgcolcg %F $MIR/src/subs/cgpgsubs.for
%D Find background colour of PGPLOT device
%P nebk
%: plotting
%B
      subroutine bgcolcg (bgcol)

      integer bgcol
  ---------------------------------------------------------------------
  Look at the RGB colours of colour index 0 to see whether the
  device background is black or white

  Output:
    bgcol      0 -> black
               1 -> white
              -1 -> something else
