emacs: Add "guix-popup.el".

* emacs/guix-popup.el: New file.
* emacs.am (ELFILES): Add it.

emacs.am

@@ -28,6 +28,7 @@ ELFILES =					\
   emacs/guix-list.el				\
   emacs/guix-messages.el			\
   emacs/guix-pcomplete.el			\
+  emacs/guix-popup.el				\
   emacs/guix-prettify.el			\
   emacs/guix-read.el				\
   emacs/guix-utils.el				\

emacs/guix-popup.el

@@ -0,0 +1,48 @@
+;;; guix-popup.el --- Popup windows library
+
+;; Copyright © 2015 Alex Kost <alezost@gmail.com>
+
+;; This file is part of GNU Guix.
+
+;; GNU Guix is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Guix is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This file provides `guix-define-popup' macro which is just an alias
+;; to `magit-define-popup'.  According to the manual (info
+;; "(magit-popup) Defining prefix and suffix commands") `magit-popup'
+;; library will eventually be superseded by a more general library.
+
+;;; Code:
+
+(require 'magit-popup)
+
+(defalias 'guix-define-popup 'magit-define-popup)
+
+(defvar guix-popup-font-lock-keywords
+  (eval-when-compile
+    `((,(rx "("
+            (group "guix-define-popup")
+            symbol-end
+            (zero-or-more blank)
+            (zero-or-one
+             (group (one-or-more (or (syntax word) (syntax symbol))))))
+       (1 font-lock-keyword-face)
+       (2 font-lock-function-name-face nil t)))))
+
+(font-lock-add-keywords 'emacs-lisp-mode guix-popup-font-lock-keywords)
+
+(provide 'guix-popup)
+
+;;; guix-popup.el ends here