Is there an event configuration where my rule would trigger on the equivalent of window.addEventListener("message" ...) ? Then even more vexxing is can I then create rule conditions filtering on the values in event.origin and event.data? Based on what I see - I think the answer is no.
Use case is I have an iframe using postMessage to let the parent window know something happened.
I suspect I will need to create my own listener. Then let that listener do the appropriate filtering and validation and then based on the payload fire the appropriate direct calls.