dart:html

Свойство onVisibilityChange

Исходный код

@SupportedBrowser(SupportedBrowser.CHROME)
@SupportedBrowser(SupportedBrowser.FIREFOX)
@SupportedBrowser(SupportedBrowser.IE, '10')
@Experimental()
Stream<Event> get onVisibilityChange => visibilityChangeEvent.forTarget(this);