LFUN
  int prevent_shadow (object by)

DESCRIPTION
  Check if this object may be shadowed (called by the gamedriver).

  Arguments:
    by: the object which wants to shadow this one.

  Result:
        0: this object may be shadowed.
    not 0: this object may not be shadowed.

  Defaultbehaviour is that clones and non-sensitive blueprints may be
  shadowed.

IMPLEMENTED
  /std/base

SEE ALSO
  base(S), shadow(E)