I miss is the ability to make J and K behave like Down and Up arrow keys. I can bind J and K either for View > Go to > Previous/Next message or View > Message scroll > Previous/Next line but I'd like to bind them for both. This shouldn't clash because it already works with arrow keys and because only one pane has focus at a given time. Perhaps at least for small screen layout it might be more easily achieavable?
It's impossible.