The sample app for authorize.net has many great examples for acceptHosted transactions, but there are no examples in the acceptCustomer markdown: https://github.com/AuthorizeNet/accept-sample-app/blob/master/README-AcceptCustomer.md
It would be great if we could get some examples of the acceptCustomer setup for the CommunicationHandler function for integrating the acceptCustomer iFrame into a web page. Your documentation suggests that the hosted form listener script should return the ideal height/width of the window, changesSaved, and requestCanceled parameters, but I can only get it to return window parameters:
this problem came up for another user, and I don't think it was resolved: