Hi,

There is a problem in vtable.el when an emoji is specified as a delimiter; the
header and row delimiters are not aligned.

Minimal reproducer for emacs -Q:

(require 'vtable)
(with-current-buffer (get-buffer-create "*test*")
  (make-vtable
   :columns '((:name "Name" :width 20) "Size" "File")
   :objects (buffer-list)
   :actions '("k" kill-buffer
              "RET" display-buffer)
   :divider " 🍉 "
   :getter (lambda (object column vtable)
             (pcase (vtable-column vtable column)
               ("Name" (buffer-name object))
               ("Size" (buffer-size object))
               ("File" (or (buffer-file-name object) "")))))
  (switch-to-buffer "*test*"))

Screenshot is attached.