What is the alternative to `alert` in metro apps?

What is the alternative to `alert` in metro apps?

References

Reference NO 1

http://stackoverflow.com/questions/13652413/what-is-the-alternative-to-alert-in-metro-apps

Reference NO 2

http://www.makeuseof.com/tag/email-goes-modern-three-windows-8-email-apps/

Reference NO 3

https://issues.apache.org/jira/browse/COUCHDB-1381

Reference NO 4

http://www.zdnet.com/blog/hardware/windows-8-app-store-will-be-the-only-source-of-metro-apps/14873

Reference NO 5

http://metrotrains.com.au/news/2013/mar/20/introducing-metronotify-our-new-smart-phone-app

Reference NO 6

http://www.techrepublic.com/blog/five-apps/windows-8-the-five-apps-you-should-install-first/

Reference NO 7

http://www.i-programmer.info/programming/c/3062-getting-started-with-c-metro-apps.html?start=1

Reference NO 8

https://itunes.apple.com/us/app/itrans-dc-metro/id284147312?mt=8