Every com.nomagic.magicdraw.uml.symbols.PresentationElement can access selected elements or change their own selection status.
Collecting selected presentation elements in a diagram
Project project = ;
DiagramPresentationElement diagram = project.getActiveDiagram();
List<PresentationElement> selected = diagram.getSelected();
Selecting element in a diagram
presentationElement.setSelected(true);
Presentation element selection events page describes selection change events
Related pages