- if( document[ 'hidden' ] !== undefined ) {// iOS 7+
- X_ViewPort_document.listen( 'visibilitychange', X_ViewPort );
+ if( document[ 'hidden' ] !== undefined ){// iOS 7+
+ X_EventDispatcher_systemListen( X_ViewPort_document, 'visibilitychange', X_ViewPort );
+ } else
+ if( document[ 'mozHidden' ] !== undefined ){
+ X_EventDispatcher_systemListen( X_ViewPort_document, 'mozvisibilitychange', X_ViewPort );