"It was a bit tricky to find a union of features that work in both engines [..]"
I am curious what the constraints are to make this work and in which environments it does? Does it work in PDF viewers outside the browser? Is there documentation what is available in which environment? What is enabled by default, can be switched on or off?
I am curious what the constraints are to make this work and in which environments it does? Does it work in PDF viewers outside the browser? Is there documentation what is available in which environment? What is enabled by default, can be switched on or off?