In Visio 2013 and later versions, the shapes are unlocked and more flexible, so you can change their behavior if needed.
If you've built UML diagrams in previous versions of Visio, you might remember using modeling or wizards to build the diagrams, which then were locked against editing or formatting. The sequence diagram is popular with software designers and IT professionals, but it's also useful in sketching out many kinds of interaction processes. In Visio, you build Unified Modeling Language (UML) sequence diagrams like any other Visio diagram, by dragging shapes onto the UML Sequence diagram template.
