A scenario is not only a place to draw flow diagrams but also a way to validate your current simulation against those flows. When you drag a screen component into the scenario's canvas the screen is represented by an icon. If that screen is renamed in such a way that the new name matches the name of a screen created in 'User Interface' then the icon is replaced by a preview of that screen. So that you can quickly view if the screens in a scenario are actual screens in your prototype. You can create an actual screen from a component in a scenario by clicking with the right mouse button on it (cmd+click in OS X systems) and selecting the 'Create also in UI' option. A new screen will be created in the 'User Interface' tab and the icon in the scenario will be replaced by a preview of that screen. The transitions are also compared to actual links in the simulation. If the transition hasn't its companion link in the screen then a warning icon appears. Once the link that links that screens is created in the 'User Interface' the warning icon will disappear. Double-click on a screen component in the scenario opens that screen in the 'User Interface' tab to edit. Check in which scenarios a screen appears by choosing the 'Scenarios' option in the contextual menu of a screen in 'User Interface'.
