> (define-key global-map 'button3 'mouse-track-adjust)
> (add-hook 'mouse-track-click-hook
>       (lambda (event count)
>         (if (or (/= (event-button event) 3)
>             (/= count 2))
>         nil
>           (kill-region (point) (mark))
>           t
>           )))

> (setq mouse-yank-at-point t)

> I am not able to get it to select the region spanning the last point where
> button1 was clicked, to the current mouse location.  To do that I have to
> highlight the region by dragging the mouse.  Presumably, I have to invoke
> some 'mark the point' function in the code above when button1 is clicked
> in the above conditional?