Stepping through an animation (Object Animator)
On the Run menu, click Step.
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Continue to step through an animation through the Step command.
If you want Object Animator to step through the animation for you, select the Go command on the Run menu.
If you have the Animate into Child Diagrams check box selected on the Options dialog and you encounter an Event, Operation or Use Case that owns multiple Sequence Diagrams, you are prompted to select which child Sequence Diagram to animate.