While previewing your presentation you have the option to also preview your Overflow diagram as a rapid prototype (auto-generated).
Only screens, shapes and images are included in the particular preview. You can enter the rapid prototype view by pressing Enter while seeing the presentation and having an element selected. You can exit either hitting Enter or ESC. You can go back to Editor directly using the button at the top left.
You can interact with your prototype by clicking on the interactive areas. Interactive areas are formed by layers that have connectors coming out of them. You can highlight interactive areas by keeping the Shift key pressed.
You can still navigate by using the Left/Right arrow keys, but this will only be meaningful if your screens are laid out in a way that implies an order (i.e. in a row).
In rapid prototype, screens with masked content automatically become scrollable.
You have many zoom modes for previewing the prototype, as seen in the screenshot below.
You also have the options to start over, show/hide interaction hints, show/hide navigation arrows, light/dark background, hide the UI and view keyboard shortcuts.