Gtk.Label.prototype.get_mnemonic_keyval

function get_mnemonic_keyval():Number {
    // Gjs wrapper for gtk_label_get_mnemonic_keyval()
}

If the label has been set so that it has an mnemonic key this function returns the keyval used for the mnemonic accelerator. If there is no mnemonic set up it returns #GDK_KEY_VoidSymbol.