I have a visualforce page in lightning console, and I need it to send messages other components in the page. This is troublesome because Salesforce always embeds VF Pages in an iframe, even in classic.
In my research, and from folks in a few different communities I heard about window.postMessage as a possible solution.
I found that the Locker API Viewer did not block it, so I sent about figuring it out.
The following regails my misconceptions and pitfalls along the way.