Determines how the image set by wallpaper_filename is rendered. Possible values are "none", "wallpaper", "centered", "scaled", "stretched", "zoom", "spanned".
'wallpaper_filename'-k ezarritako irudia nola errendatzen den zehazten du. Balio posibleak hauek dira: "none", "wallpaper", "centered", "scaled", "stretched", "zoom", "spanned".