(gobject:define-gflags "GtkIconLookupFlags" icon-lookup-flags
  (:export t
   :type-initializer "gtk_icon_lookup_flags_get_type")
  (:none 0)
  (:force-regular  #.(ash 1 0))
  (:force-symbolic #.(ash 1 1))
  (:preload        #.(ash 1 2)))  

:none

No flags set.

:force-regular

Try to always load regular icons, even when symbolic icon names are given.

:force-symbolic

Try to always load symbolic icons, even when regular icon names are given.

:preload

Starts loading the texture in the background so it is ready when later needed.