We are introducing a redesigned compose experience in Gmail that saves you time, uses less screen space, and is simple to use. The new compose experience opens a window at the bottom of your inbox. You can compose multiple messages at once, search through your inbox and even reply to other messages all while keeping your new draft open.

NOTE: Users will be able to opt-out of this new experience for two weeks.

Release track:
Rapid release

Editions included:
Google Apps, Google Apps for Business, Government and Education

For more information:
http://support.google.com/mail/bin/answer.py?answer=2645922
http://gmailblog.blogspot.com.au/2013/03/gmails-new-compose-now-default.html

whatsnew.googleapps.com
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