(gobject:define-genum "GtkButtonBoxStyle" button-box-style
  (:export t
   :type-initializer "gtk_button_box_style_get_type")
  (:spread 1)
  (:edge 2)
  (:start 3)
  (:end 4)
  (:center 5)
  (:expand 6))  

:spread

Buttons are evenly spread across the box.

:edge

Buttons are placed at the edges of the box.

:start

Buttons are grouped towards the start of the box, on the left for a horizontal box, or the top for a vertical box.

:end

Buttons are grouped towards the end of the box, on the right for a horizontal box, or the bottom for a vertical box.

:center

Buttons are centered in the box.

:expand

Buttons expand to fill the box. This entails giving buttons a "linked" appearance, making button sizes homogeneous, and setting spacing to 0, same as calling the gtk:box-homogeneous and gtk:box-spacing functions manually.