constructor( Reveal ) {

		this.Reveal = Reveal;

		this.onRevealPointerDown = this.onRevealPointerDown.bind( this );
		this.onDocumentPointerDown = this.onDocumentPointerDown.bind( this );

	}
Manages focus when a presentation is embedded. This
helps us only capture keyboard from the presentation
a user is currently interacting with in a page where
multiple presentations are embedded.