Adds a widget to the list of mnemonic labels for this widget.
See [method@Gtk.Widget.list_mnemonic_labels]. Note the
list of mnemonic labels for the widget is cleared when the
widget is destroyed, so the caller must make sure to update
its internal state at this point as well.
Adds a widget to the list of mnemonic labels for this widget.
See [method@Gtk.Widget.list_mnemonic_labels]. Note the list of mnemonic labels for the widget is cleared when the widget is destroyed, so the caller must make sure to update its internal state at this point as well.