supertux/data/images/objects/keys/key_air.sprite

(supertux-sprite
 (action
  (name "default")
  (images "air.png"
)
 )
 (action
  (name "display")
  (images "air_display.png")
 )
 (action
  (name "outline")
  (images "n_outline.png")
 )
)