Re: Using overlay in register

[Richard Stallman]

This is a very good idea.  Thanks for working on it.

I see a possible bug here:

    +(defun register-put-overlay-at-point (register)
    +  "Put a overlay associated with REGISTER at the point."
    +  (let ((overlay (make-overlay (point) 
    +                          (1+ (point))
    +                          (current-buffer)

This will get an error at the end of the buffer.

What should it do at the end?  Make an empty overlay?
It could have a before-string, perhaps.

    +(defun register-get-overlay-position (overlay)
    +  "Get the position for OVERLAY."
    +  (min (overlay-start overlay) (overlay-end overlay)))

What's the purpose of using min here?
Why not just use overlay-start?
(In some places you did so.)