The InfoFullScreen dialog action is currently a preview feature that works but may not be complete and is subject to change.
The InfoFullScreen action displays information to the end-user using a full-screen window instead of a standard UI++ dialog. This full-screen window displays an optional image, a single line of text, and an infinite progress bar.
To dismiss the full-screen window, press Ctrl + Alt + F10. This is not currently configurable.
The following snippet creates an InfoFullScreen action full-screen dialog.
<Action Type="InfoFullScreen" Image="http://home.configmgrftw.com/images/ElkwaterUnited-big.png">Glorious things are happening in the background.</Action>