let get_font (tag : string) (choices : string list) : Tk.font =
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
| "" -> Font.create ~name:tag ~size:10 ()
| fam -> Font.create ~name:tag ~family:fam ~size:10 ()