Improved Communication with embedded iframe (anywhere)

On behalf of Customer SMT Data:

In our product we're embedding targit reports through an iframe. However, when we do this it essentially acts as a black box. We can't see if something wen't wrong such as an error message being shown or if targit is currently loading. Likewise, we would also like to affect things inside of targit such as the toolbar being shown. So to sum it up, we would like a method to: 

- See the state of targit/have an understanding of what is going on inside the "black box"
- Send commands to the embedded targit to for example hide the toolbar 
- See error messages whenever they occur, so we can handle them in our host application. 

What we're currently doing to solve this, is upload a javascript script to the targit installations, which listens for specific events and then uses the postMessage web api to communicate what is happening inside the iframe. This is very unstable as it's our own mcgyvered solution. 

Two solution suggestions for now, should be: 

1. have an officically supported postMessage api for two-way communication with the iframe. 

2. have an officically supported way of uploading javascript scripts as plugins, that can hook into certain events and handle them, themselves.