I feel like you should be able to reference a View-level Parameter or Custom attribute as the Message Type when setting up the message handler for onMessageRecieved.
I’ve tried view.custom.returnMessageId and parent.view.custom.returnMessageId
as Custom attributes and Params, with and without the curly braces.
Having this custom attribute works fine for passing it into the system.perspective.openPopup call. The popup view receives it as a parameter and is able to use it as a reference when sending a message back to the calling view. I would have thought it should have worked the same way when setting up the message handler on the receiving side.
Any thoughts on this?