function onFullscreenChange( event ) {

		let element = document.fullscreenElement || document.webkitFullscreenElement;
		if( element === dom.wrapper ) {
			event.stopImmediatePropagation();

			// Timeout to avoid layout shift in Safari
			setTimeout( () => {
				Reveal.layout();
				Reveal.focus.focus(); // focus.focus :'(
			}, 1 );
		}

	}
Handler for the document level 'fullscreenchange' event.

@param {object} [event]