; showzoom
if ($zoom == 1) exit
if ($dim!=2) error " in 2D Only"
 showline $zoom_2d[2] $zoom_2d[1] $zoom_2d[2] $zoom_2d[3]
 showline $zoom_2d[2] $zoom_2d[3] $zoom_2d[4] $zoom_2d[3]
 showline $zoom_2d[4] $zoom_2d[3] $zoom_2d[4] $zoom_2d[1]
 showline $zoom_2d[4] $zoom_2d[1] $zoom_2d[2] $zoom_2d[1]

