lisp/frameset.el: Make list-registers a bit more informative.

(frameset--print-register): New function.
(frameset-to-register): Use it.

lisp/ChangeLog

+2014-03-21  Juanma Barranquero  <lekktu@gmail.com>
+
+	* frameset.el (frameset--print-register): New function.
+	(frameset-to-register): Use it.
+
 2014-03-20  Juanma Barranquero  <lekktu@gmail.com>
 	* progmodes/hideif.el (hif-string-to-number): New function.

lisp/frameset.el

@@ -1271,6 +1271,17 @@ Called from `jump-to-register'.  Internal use only."
 	(set-frame-selected-window frame window)
 	(with-current-buffer buffer (goto-char (aref data 2)))))))
 
+;;;###autoload
+(defun frameset--print-register (data)
+  "Print basic info about frameset stored in DATA.
+Called from `list-registers' and `view-register'.  Internal use only."
+  (let* ((fs (aref data 0))
+	 (ns (length (frameset-states fs))))
+    (princ (format "a frameset (%d frame%s, saved on %s)."
+		   ns
+		   (if (= 1 ns) "" "s")
+		   (format-time-string "%c" (frameset-timestamp fs))))))
+
 ;;;###autoload
 (defun frameset-to-register (register)
   "Store the current frameset in register REGISTER.
@@ -1288,7 +1299,7 @@ Interactively, reads the register using `register-read-with-preview'."
 			 ;; in the current buffer, so record that separately.
 			 (frameset-frame-id nil)
 			 (point-marker))
-		 :print-func (lambda (_data) (princ "a frameset."))
+		 :print-func #'frameset--print-register
 		 :jump-func #'frameset--jump-to-register)))
 
 (provide 'frameset)