PRO plrect,x1,x2,y1,y2,colo

; Overplot a rectangle with
; lower left corner at (x1,y1) and
; upper right corner at (x2,y2);
; color of the rectangle = col.

if n_params() eq 4 then colo=0

plots,[x1,x2,x2,x1,x1],[y1,y1,y2,y2,y1],col=colo,/device
;plots,[x1,x2],[y1,y2],/device
;plots,[x2,x1],[y1,y2],/device
END