vents to the current slide window.
				 * This enables keyboard events to work even if focus
				 * isn't set on the current slide iframe.
				 */
				function setupKeyboard() {

					document.addEventListener( 'keydown', function( event ) {
						currentSlide.contentWindow.postMessage( JSON.stringify({ method: 'triggerKey', args: [ event.keyCode ] }), '*' );
					} );

				}

				/**
				 * Creates the preview iframes.
				 */
				function setupIframes( data ) {

					var params = [
						'receiver',
					