ListBoxSplit(x) コマンドは、リストボックスの値を文字列のリストに変換します。

with(Maplets[Elements]):
maplet := Maplet([
   ["Pick your favorite Canadian capital(s):  ", ListBox['LB1'](sort([
      "Ottawa, ON", "Victoria, BC", "Edmonton, AB", "Regina, SK",
      "Winnipeg, MN", "Toronto, ON", "Quebec City, PQ", "Fredericton, NB",
      "Halifax, NS", "Charlottetown, PI", "St. John's, NF", "Whitehorse, YT",
      "Yellowknife, NT", "Iqaluit, NU"
   ], lexorder))],
   [Button("OK", Shutdown(['LB1'])), Button("Cancel", Shutdown())]
]):
result := Maplets[Display](maplet):
if type( result, ['string'] ) then
   Maplets[Tools][ListBoxSplit](result[1]);
end if;

Maplets[Tools][ListBoxSplit]("Victoria, BC,Halifax, NS");