(define-g-enum "GtkPolicyType" gtk-policy-type
  (:export t
   :type-initializer "gtk_policy_type_get_type")
  (:always 0)
  (:automatic 1)
  (:never 2)
  (:external 3))  

:always

The scrollbar is always visible. The view size is independent of the content.

:automatic

The scrollbar will appear and disappear as necessary. For example, when all of a gtk-tree-view widget cannot be seen.

:never

The scrollbar should never appear. In this mode the content determines the size.

:external

Do not show a scrollbar, but do not force the size to follow the content. This can be used e.g. to make multiple scrolled windows share a scrollbar.