Mu4e: add support for composing in a new frame

Adds the variable mu4e-compose-in-new-frame and when set to t, message
are composed in a new frame rather than the current one.

mu4e/mu4e-compose.el

@@ -1,3 +1,4 @@
+;; -*-mode: emacs-lisp; tab-width: 8; indent-tabs-mode: t -*-
 ;; mu4e-compose.el -- part of mu4e, the mu mail user agent for emacs
 ;;
 ;; Copyright (C) 2011-2012 Dirk-Jan C. Binnema
@@ -401,7 +402,14 @@ the appropriate flag at the message forwarded or replied-to."
     (when (and (buffer-file-name buf)
                (string= (buffer-file-name buf) path)
                message-kill-buffer-on-exit)
-      (kill-buffer buf)))
+      (if (and mu4e-compose-in-new-frame (window-system))
+	  (progn
+	    (switch-to-buffer buf)
+	    (when (and (get-buffer-window buf)
+		       (window-frame (get-buffer-window buf)))
+	      (kill-buffer buf)
+	      (delete-frame (window-frame (get-buffer-window buf))))
+	(kill-buffer buf)))))
   ;; now, try to go back to some previous buffer, in the order
   ;; view->headers->main
   (if (buffer-live-p mu4e~view-buffer)

mu4e/mu4e-draft.el

@@ -73,6 +73,12 @@ message; if nil, only do so when sending the message."
   :type 'boolean
   :group 'mu4e-compose)
 
+(defcustom mu4e-compose-in-new-frame nil
+  "Whether to compose messages in a new frame instead of the
+current window."
+  :type 'boolean
+  :group 'mu4e-compose)
+
 (defun mu4e~draft-user-agent-construct ()
   "Return the User-Agent string for mu4e.
 This is either the value of `mu4e-user-agent', or, if not set, a
@@ -414,7 +420,9 @@ from either `mu4e~draft-reply-construct', or
       ;; path, but we cannot really know 'drafts folder'... we make a guess
       (progn
 	(setq draft-dir (mu4e~guess-maildir (mu4e-message-field msg :path)))
-	(find-file (mu4e-message-field msg :path)))
+        (if (and mu4e-compose-in-new-frame (window-system))
+            (find-file-other-frame (mu4e-message-field msg :path))
+          (find-file (mu4e-message-field msg :path))))
       ;; case-2: creating a new message; in this case, we can determing
       ;; mu4e-get-drafts-folder
       (progn
@@ -424,7 +432,9 @@ from either `mu4e~draft-reply-construct', or
 		  mu4e-maildir
 		  draft-dir
 		  (mu4e~draft-message-filename-construct "DS"))))
-	  (find-file draft-path))
+          (if (and mu4e-compose-in-new-frame (window-system))
+              (find-file-other-frame draft-path)
+            (find-file draft-path)))
 	(insert
 	  (case compose-type
 	    (reply   (mu4e~draft-reply-construct msg))

mu4e/mu4e.texi

@@ -3428,6 +3428,8 @@ Sending...done
 @end verbatim
 The first and final messages are the most important, and there may be
 considerable time between them, depending on the size of the message.
+@item @emph{Is it possible to compose messages in a separate frame?} 
+Yes - set the variable @code{mu4e-compose-in-new-frame} to @code{t}.
 @item @emph{How can I apply format=flowed to my outgoing messages, enabling
 receiving clients that support this feature to reflow my paragraphs?}
 Plain text emails with @t{Content-Type: text/plain; format=flowed} can
@@ -3486,8 +3488,8 @@ when sending a reply to some e-mail. This seems to be caused by
 @t{mu4e} is working on it. To prevent this, deactivate @t{notmuch} in
 your Emacs setup.
 @item @emph{The PDF-version of the manual does not show any of the non-ASCII
-characters} - this is because, sadly, @t{texi2pdf} documentation system
-does not support those. There is not much we can do about that.
+characters} - this is because the @t{texi2pdf} documentation system does
+not support those. There is not much we can do about that.
 @end itemize
 
 For a more complete list, please refer to the issues-list in the