@interlisp ☝️ I've been using the SEdit structure editor of Medley Interlisp for the past couple of years and I'm now more fluent with keyboard and mouse gestures, which work very well together to efficiently manipulate Lisp code.
The lack of support for cursor keys and keyboard navigation doesn't get in the way of editing. In addition to quick mouse gestures, the most common cases of cursor movement are handled by other keys such as ) for moving outside and Backspace for moving inside a list.