add_list
(add_list string)
This function adds or replaces an item in a dialog box list of type list_box or popup_list. The type of operation is determined by a preceding start_list function call.
Return Value
string specifies the item that is being added to the list or the item that is replacing an existing list item.
Return Value
If the operation was successful, the function returns the value of the string argument, otherwise it returns nil.