NSStandardKeyBindingResponding

Cool tricks with Key Bindings:

• defaults write -g NSRepeatCountBinding -string "^u"

Then:

• In your override func keyDown(with event: NSEvent), for any standard functionality, call interpretKeyEvents[event])
• For basic moving/editing, have your NSView implement methods from NSStandardKeyBindingResponding (pre-10.14: NSResponder).

Your view now supports whatever keybindings the user wishes! Including, by default, Emacs-style.