Action m = CTEFactoryImpl.eINSTANCE.createAction();
             		m.setName("kkkk");
             		CreateElementRequest kommschon = new CreateElementRequest(k.getEditingDomain(),m,ActivityElementTypes.Action_2001);
             		
             		CreateElementCommand createElementCommand = new CreateElementCommand(kommschon);

             		k.getDiagramEditDomain().getDiagramCommandStack().execute(new ICommandProxy(createElementCommand));

List types = Collections.singletonList(ActivityElementTypes.Action_2001);
CreateUnspecifiedTypeRequest gefRequest = new CreateUnspecifiedTypeRequest(types, PreferencesHint.USE_DEFAULTS);
gefRequest.setLocation(...);
gefRequest.setSize(...);
EditPart containerEP = .... //find EP that should host the new element, DiagramEditPart for top-level elements.
Command gefCommand = containerEP.getCommand(gefRequest);
if (gefCommand.canExecute()) {
   //execute 
}