module Main (main) whereimport HTkmain :: IO ()main =  do main <- initHTk [text "A Listbox"]     lb  <- newListBox main [value numbers, bg "white",                             size (15, 10)] :: IO (ListBox String)     pack lb [Side AtLeft]     scb <- newScrollBar main []     pack scb [Side AtRight, Fill Y]     lb # scrollbar Vertical scb     (press, _) <- bindSimple lb (ButtonPress (Just 1))     lb # selectMode Extended     spawnEvent (forever       (press >> always           (do sel<- getSelection lb              putStrLn ("Selected "++                         show (sel:: Maybe [Int])))))     finishHTk where  numbers =     ["One", "Two", "Three", "Four", "Five", "Six", "Seven",     "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen",     "Fourteen", "Fifteen", "Sixteen", "Seventeen",     "Eighteen", "Nineteen", "Twenty"]