Undocumented in source.
gio.ThemedIcon is an implementation of GIcon that supports icon themes. gio.ThemedIcon contains a list of all of the icons present in an icon theme, so that icons can be looked up quickly. gio.ThemedIcon does not provide actual pixmaps for icons, just the icon names. Ideally something like IconTheme.chooseIcon should be used to resolve the list of names so that fallback icons work nicely with themes that inherit other themes.