Some sample applications of this include:
iFrame to Parent Page Communication
Broadcast iframe height to allow for flexible length embedded content without scroll bars.
Return Query metadata on Explore pages to store user sessions on the parent site.
Broadcast dashboard clicks and run events from the iframe to trigger actions on the parent page.
Parent to iframe Communication
Pass in user specified custom filter values outside of the iframe into the iframe
Load and run dashboards based on specific user actions on the parent page.