listbox get -- returns the number of the currently selected item in a listbox
ItemNumber = LISTBOX GET ListBox$
To obtain the item that is currently selected in the listbox named ListBox$, simply use this command. If no item is selected, ItemNumber will be set to 0.
Have a look at the listbox command for an example.
listbox, listbox add, listbox clear, listbox count, listbox get$, listbox remove, listbox select, listbox sort