public UiTopoLayout sprites(String sprites) {
        if (geomap != null) {
            throw new IllegalArgumentException(E_GEOMAP_SET);
        }
        this.sprites = sprites;
        return this;
    }
@Test
    public void setSprites() {
        mkRootLayout();
        assertEquals("sprite to start", null, layout.sprites());
        layout.sprites(SPRITE);
        assertEquals("wrong sprite", SPRITE, layout.sprites());
    }