I found out this weekend in the CC Javascript Tool Guide that various little things were removed from extendscript, for example I was using addEventListener('click', ... on some buttons and 'click' doesn't seem to be available anymore.
It would really help if instead of being removed straight away things were flagged as deprecated first, and if the Extendscript Toolkit could warn us about deprecated stuff. Are there any plans to enhance the toolkit a bit? It's very useful and well integrated in the suite but a bit too minimalistic.