GTK does this automatically based on mnemonics, but only
if the string actually contains a mnemonic. This makes
orca read out menuitems, as expected.
gtk_label_set_text_with_mnemonic (GTK_LABEL (button->label),
text ? text : "");
update_visibility (button);
+
+ gtk_accessible_update_relation (GTK_ACCESSIBLE (button),
+ GTK_ACCESSIBLE_RELATION_LABELLED_BY, g_list_append (NULL, button->label),
+ -1);
+
g_object_notify_by_pspec (G_OBJECT (button), properties[PROP_TEXT]);
}