con esta opción activada puedo visualizar el tema pero no los iconos:
Theme designer modethemedesignermode
Default: No
Normally all theme images and style sheets are cached in browsers and on the server for a very long time, for performance. If you are designing themes or developing code then you probably want to turn this mode on so that you are not served cached versions. Warning: this will make your site slower for all users! Alternatively, you can also reset the theme caches manually from the Theme selection page.