I was puzzled when I first saw cross tab communication in impress.js for their slide control tab (slid.es) and I am still wondering about the proper use case of this feature today. Isn't this a security nightmare?
All boils down the sender using a specific target, and the receiver remembering to check the origin.
http://www.riskcompletefailure.com/2013/03/postmessage-oauth...