function onPreviewLinkClicked( event ) {

		if( event.currentTarget && event.currentTarget.hasAttribute( 'href' ) ) {
			var url = event.currentTarget.getAttribute( 'href' );
			if( url ) {
				showPreview( url );
				event.preventDefault();
			}
		}

	}
Handles clicks on links that are set to preview in the
iframe overlay.