;; From <http://www.kollektiv-hamburg.de/~forcer/hisex.el>:

;;; Code thrown together by Jorgen Schaefer
;;; Placed into the public domain. All rites reversed. Use at your own risk.

(defface hisex-face '((t :background "blue"))
  "The face used to highlight sexps.")

(defvar hisex-overlay nil
  "The overlay used for `hisex-mode'.")

(define-minor-mode hisex-mode
  "Highlight the current expression."
  :group 'paredit
  (if hisex-mode
      (progn
        (add-hook 'post-command-hook 'hisex-highlight nil t)
        (hisex-highlight))
    (remove-hook 'post-command-hook 'hisex-highlight)
    (when hisex-overlay
      (delete-overlay hisex-overlay)
      (setq hisex-overlay nil))))

(defun hisex-highlight ()
  "Set `hisex-overlay'."
  (let ((beg nil)
        (end nil))
    (condition-case nil
        (progn
          (save-excursion
            (up-list)
            (setq end (point))
            (backward-sexp)
            (setq beg (point)))
          (if hisex-overlay
              (move-overlay hisex-overlay beg end)
            (setq hisex-overlay (make-overlay beg end))
            (overlay-put hisex-overlay 'face 'hisex-face)))
      (scan-error
       (when hisex-overlay
         (delete-overlay hisex-overlay)
         (setq hisex-overlay nil))))))