// Don't let the "new stair" icon cover up any existing icons, but
    // draw it otherwise.
    if (bg0 & TILE_FLAG_NEW_STAIR && status_shift == 0)
    {
        tcache_overlay(tc_img, ix, TILE_NEW_STAIR,
            TREGION_0_NORMAL, &c, NULL);
    }

                    if (is_travelable_stair((dungeon_feature_type)object) &&
                        !travel_cache.know_stair(gc))
                    {
                        tile_dngn[gc.x][gc.y] |= TILE_FLAG_NEW_STAIR;
                    }

new_stair NEW_STAIR