pro poly_bounds,x,y,N=n
  if n_elements(n) eq 0 then n=10
  if n_elements(x) eq 0 then begin 
     x=[1.2,3,5.3,3.2] & y=[1.3,6.4,4.3,2.2]
  endif
  window,XSIZE=500,YSIZE=500
  ;; Set up the plot region, etc.
  plot,[0],[0],XRANGE=[0.,n],YRANGE=[0.,n], XMINOR=-1,YMINOR=-1, $
       XTICKS=n,YTICKS=n,POSITION=[.05,.05,.95,.95],TICKLEN=0,/NODATA
  p=polyfillv(x,y,n,n)
  for i=0,n_elements(p)-1 do begin 
     xp=p[i] mod n
     yp=p[i]/n
     polyfill,[xp,xp,xp+1,xp+1],[yp,yp+1,yp+1,yp],COLOR=!D.N_COLORS/2
  endfor
  oplot,[x,x[0]],[y,y[0]]
  for i=0,n-1 do begin
     plots,i,!Y.CRANGE
     plots,!X.CRANGE,i
     for j=0,n-1 do begin
        plots,i+.5,j+.5,PSYM=3
        xyouts,i+.1,j+.1,strtrim(i+j*n,2)
     endfor
  endfor
end