This property is used if property@Gtk.ShortcutsShortcut:shortcut-type is set to [gtk.types.ShortcutType.Accelerator].
The syntax of this property is (an extension of) the syntax understood by func@Gtk.accelerator_parse. Multiple accelerators can be specified by separating them with a space, but keep in mind that the available width is limited.
It is also possible to specify ranges of shortcuts, using `...` between the keys. Sequences of keys can be specified using a `+` or `&` between the keys.