I was only involved in one major project that relied heavily on CodeMirror since version 2.something. I participated in moving the project from version 2->3 and

I was only involved in one major project that relied heavily on CodeMirror since version 2.something. I participated in moving the project from version 2->3 and 3->4 (but not 4->5 which someone else did), and for those moves, the editor API didn't change very drastically as far as I can remember. Maybe the 4->5 migration was bigger?