Try this:

(define-key mode-line-buffer-identification-keymap [mode-line mouse-3] 'list-buffers)

That does not show buffers whose names begin with a space. If you really want to show all buffers, then try this instead:

(define-key mode-line-buffer-identification-keymap
            [mode-line mouse-3]
            (lambda ()
              (interactive)
              (display-buffer (list-buffers-noselect nil (buffer-list)))))

(However, I agree with those who commented that this is a very useful thing to do.)

Try this:

(define-key mode-line-buffer-identification-keymap [mode-line mouse-3] 'list-buffers)

That does not show buffers whose names begin with a space. If you really want to show all buffers, then try this instead:

(define-key mode-line-buffer-identification-keymap
            [mode-line mouse-3]
            (lambda ()
              (interactive)
              (display-buffer (list-buffers-noselect nil (buffer-list)))))

(However, I agree with those who commented that this is a very useful thing to do.)

Try this:

(define-key mode-line-buffer-identification-keymap [mode-line mouse-3] 'list-buffers)

Or if you really want to show all buffers:

(define-key mode-line-buffer-identification-keymap
            [mode-line mouse-3]
            (lambda () (interactive) (list-buffers nil (buffer-list))))

However, I agree with those who commented that this is not so useful.

Try this:

(define-key mode-line-buffer-identification-keymap [mode-line mouse-3] 'list-buffers)

That does not show buffers whose names begin with a space. If you really want to show all buffers, then try this instead:

(define-key mode-line-buffer-identification-keymap
            [mode-line mouse-3]
            (lambda ()
              (interactive)
              (display-buffer (list-buffers-noselect nil (buffer-list)))))

(However, I agree with those who commented that this is a very useful thing to do.)