/**
 * @author Naoki Watanabe
 */
function navigation_active(object){
	if (object.src.match(/_active\.(?=(jpg|gif|png)$)/i) == null) {
		object.src = object.src.replace(/\.(?=(jpg|gif|png)$)/i, "_active.")
	}
}
function navigation_inactive(object){
	if (object.src.match(/_active\.(?=(jpg|gif|png)$)/i)) {
		object.src = object.src.replace(/_active\.(?=(jpg|gif|png)$)/i, ".")
	}
}