wx:get-single-choice-index

• (wx:get-single-choice-index message caption choices parent x y center? width height) -> small integer
      message : string
      caption : string
      choices : list of strings
      parent = null : wx:window object or null
      x = -1 : small integer
      y = -1 : small integer
      center? = #t : boolean
      width = 150 : small integer
      height = 200 : small integer

  Like wx:get-single-choice, but the return value is the position of the selected item instead of the name. If the user presses ``Cancel'', the return value is -1. The choices are numbered starting from 0.