let get_font (tag : string) (choices : string list) : unit =
let all = Font.families () in
let rec find ch =
match ch with
| [] -> ""
| f::tail ->
( try (List.find (( = ) f) all)
with Not_found -> find tail ) in
match find choices with
| "" -> list_font:=(Font.create ~name:tag ~size:(!current_font_size) ())::(!list_font)
| fam -> list_font:=(Font.create ~name:tag ~family:fam ~size:(!current_font_size) ())::(!list_font)