Stages Tabs
If you are working with a multi-stage model, the Stage Tabs allow you to view and edit the model at each stage. The number of stages is defined in the Project Settings dialog.
The Stage Tabs appear at the bottom of the application window, below the Viewports. To view any stage click on a Stage Tab with the mouse, or use the drop down.
Rename Stages
The stage names can be customized in the Stages section of the Project Settings dialog.