private boolean enabled() {
			boolean blocked = false;

			final Iterator<Validator> i = validators.iterator();
			while (i.hasNext()) {
				final Validator c = i.next();
				if (!c.enabled.get()) {
					c.pop();
					i.remove();
				} else if (!blocked && !c.valid()) {
					blocked = true;
				}
			}

			return !blocked;
		}