set target old target model element remov model element listen list target target model element model ad element listen target function call user chang target result uml model chang block fire list event complet set build model durat function function look lot like uml combo box model param target target set target object target target target fig fig target owner target model facad auml element target target diagram model facad auml element list target model pump remov model event listen list target event allow listen element remov model event listen list target model facad auml element target list target target model pump add model event listen list target event allow listen element add model event listen list target rebuild model list list target remov element 