You can add a new option for the icons setting in the Theme preference tool. Icons options reside in the /usr/share/icons/option-name directory. The typical structure of an icons option in the file system is as follows:
Gaia hobespen-tresnako ikono-ezarpenen aukera berri bat gehi daiteke. Ikono-aukerak /usr/share/icons/aukera-izena/metacity-1 direktorioan daude. Fitxategi-sistemako ikono-aukeren ohiko egitura honelakoa da: