listbox: Cosmetic cleanup
listbox: Cosmetic cleanup

We don't cast these arguments anywhere else, so lets not do here
either.

grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita