Adds multiple buttons.
This is the same as calling [method@Gtk.InfoBar.add_button] repeatedly. The variable argument list should be null-terminated as with [ctor@Gtk.InfoBar.new_with_buttons]. Each button must have both text and response ID.
this |
a `GtkInfoBar` |
... |
response ID for first button, then more text-response_id pairs, ending with null |
first_button_text |
button text |