good question. I personally don't use it that often. In it's current state you'd have to fallback to atom shortcuts

maybe we can use the vim-ey C-w <direction>

Thanks @dvcrn - C-w <direction> works for getting to the repl but it doesn't work for getting back to the main editor. I'll look into modifying the proto-repl keybindings to give me a "last window" option or some such.