CHANGE DEPTH

    The  GTV segments have a depth attribute in order to create, control, or
    reorder different drawing layers. Depth value must lie in range 1-40.

    By default, all vector-like segments are at depth 1. Images  are  always
    at  the  deepest  available depth (2 at startup) so that e.g. the BOX is
    always drawn on top of a PLOT, independently of their creation order.

    In practice, when the plotting window is refreshed, it draws  first  all
    the  segments  at  deepest level, then all the segments at deepest level
    minus one, and so on up to level 1. For  a  given  depth,  segments  are
    drawn in chronological order (i.e. in the order they were created).