AIR applications use the standard windowing system of the OS,
and you can build AIR applications using Flex and HTML. "Widgets"
can mean a lot of different things. AIR does not support Mac OS
dashboard widgets, although you can build applications that provide
similar functionality. Also, you can build applications that expose
AIR runtime APIs to third-party content that are installed as
widgets using the AIR sandbox bridge. For details on building AIR