Presentation & Interaction
To start the presentation mode, click the "Present In-Place" button in the toolbar or via the corresponding shortcut ⌃ ⌘ P.

In-place mode is useful when you want to try out state changes and interactions. If In-Place mode is enabled, the cursor changes to the interaction cursor when you move the mouse pointer over interactive elements.
After you have performed some actions, you can switch to a selection cursor by pressing D and make changes without leaving the presentation mode. By pressing R you can switch back to the interaction mode.
This is especially useful if you want to modify elements that are initially hidden.
Terminating in-place mode, resets the screen to the previous state, but keeps the changes made. To exit the presentation mode, press the escape ESC key or ⌃ ⌘ P.
Attention
State changes performed through interaction are not reflected in the user interface. That is, if you change a widget from Normal to Selected in interaction mode and then switch to selection mode, the widget is still in its normal state.
To open the Live Preview, click the Export menu button and choose Live Preview.

The Live Preview is intended to present the prototype in the browser or on other devices e.g. mobile Devices.
It is even possible to use the Live Preview on multiple devices at the same time. This can be pretty handy when working on responsive designs.
Attention
Using Live Preview and In-Place presentation mode at the same time can cause problems.