* mu4e-send.el: use more descriptive buffer names, based on Subject:, if any

emacs/mu4e-send.el

@@ -318,6 +318,7 @@ use the new docid. Returns the full path to the new message."
     (add-hook 'before-save-hook 'mu4e-remove-mail-header-separator)
     (add-hook 'after-save-hook
       (lambda ()
+	(mu4e-set-buffer-name)
 	(mu4e-insert-mail-header-separator)
 	(set-buffer-modified-p nil)))
 
@@ -344,6 +345,23 @@ use the new docid. Returns the full path to the new message."
     (setq default-directory (expand-file-name "~/")))
 
 
+(defconst mu4e-send-buffer-max-name-length 20
+  "Maximum length of the mu4e-send-buffer-name.")
+
+(defun mu4e-set-buffer-name (&optional compose-type)
+  "Set some user-friendly buffer name based on the compose type."
+  (let* ((subj (message-field-value "subject"))
+	  (subj (unless (and subj (string-match "^[:blank:]*$" subj)) subj))
+	  (str (or subj
+		 (case compose-type
+		   (reply       "*reply*")
+		   (forward     "*forward*")
+		   (otherwise   "*draft*")))))
+    (rename-buffer (generate-new-buffer-name
+		     (truncate-string-to-width str
+		       mu4e-send-buffer-max-name-length
+		       nil nil t)))))
+
 
 (defun mu4e-send-compose-handler (compose-type &optional original-msg includes)
     "Create a new draft message, or open an existing one.
@@ -408,6 +426,8 @@ using Gnus' `message-mode'."
 	(message-goto-to)
 	(message-goto-body))
 
+      (mu4e-set-buffer-name compose-type)
+
       ;; buffer is not user-modified yet
       (set-buffer-modified-p nil)))