Adds a 'choice' to the file chooser.
This is typically implemented as a combobox or, for boolean choices, as a checkbutton. You can select a value using [
method@Gtk.FileChooser.set_choice] before the dialog is shown, and you can obtain the user-selected value in the [signal@Gtk.Dialog:
GtkFileChooser:response] signal handler using [method@Gtk.FileChooser.get_choice].
id for the added choice
user-visible label for the added choice
ids for the options of the choice, or null for a boolean choice
user-visible labels for the options, must be the same length as