overrid action perform action event ae action perform ae argo diagram diagram util activ diagram editor ce global cur editor mutabl graph model mgm mutabl graph model ce graph model enumer ce select manag select element element select sel select element object owner sel content owner add mgm add node relat edg owner collect model facad comment owner iter iter object annot element fig present annot element add diagram remov list edg mgm edg owner edg add mgm edg owner iter edg iter object edg model facad associ end edg edg model facad associ edg fig fig present edg fig fig remov diagram doe work comment edg collect model facad comment owner iter iter object annot element fig present annot element remov diagram 