properti chang properti chang event add associ event properti equal base sourc target object clazz chang element add model facad own element clazz model pump add model event listen clazz own element properti equal own element model facad base target contain sourc add element chang element remov associ event properti equal base sourc target object clazz chang element model pump remov model event listen clazz own element properti equal own element model facad base target contain sourc remov element chang element properti chang 