Use <up> and <down> keys to move point in the multi-line minibuffer.

* lisp/bindings.el (minibuffer-local-map): Rebind [down] from
next-history-element to next-line-or-history-element, and [up]
from previous-history-element to previous-line-or-history-element.

* lisp/simple.el (next-line-or-history-element)
(previous-line-or-history-element): New commands.

http://lists.gnu.org/archive/html/emacs-devel/2014-11/msg00822.html

etc/NEWS

@@ -133,6 +133,14 @@ Unicode standards.
 
 * Changes in Specialized Modes and Packages in Emacs 25.1
 
+** Minibuffer
+
+*** You can use <up> and <down> keys to move point in the multi-line
+minibuffer just as in an ordinary buffer.  Only when point moves over
+the bottom/top of the minibuffer it goes to the next/previous history
+element.  The new commands bound to <up> and <down> in the minibuffer:
+`next-line-or-history-element' and `previous-line-or-history-element'.
+
 ** Search and Replace
 
 *** Query-replace history is enhanced.

lisp/ChangeLog

@@ -1,3 +1,13 @@
+2014-11-18  Juri Linkov  <juri@linkov.net>
+
+	* bindings.el (minibuffer-local-map): Rebind [down] from
+	next-history-element to next-line-or-history-element, and [up]
+	from previous-history-element to previous-line-or-history-element.
+
+	* simple.el (next-line-or-history-element)
+	(previous-line-or-history-element): New commands.
+	http://lists.gnu.org/archive/html/emacs-devel/2014-11/msg00822.html
+
 2014-11-18  Leo Liu  <sdl.web@gmail.com>
 
 	* emacs-lisp/nadvice.el (define-advice): New macro.

lisp/bindings.el

@@ -839,11 +839,11 @@ if `inhibit-field-text-motion' is non-nil."
 (let ((map minibuffer-local-map))
   (define-key map "\en"   'next-history-element)
   (define-key map [next]  'next-history-element)
-  (define-key map [down]  'next-history-element)
+  (define-key map [down]  'next-line-or-history-element)
   (define-key map [XF86Forward] 'next-history-element)
   (define-key map "\ep"   'previous-history-element)
   (define-key map [prior] 'previous-history-element)
-  (define-key map [up]    'previous-history-element)
+  (define-key map [up]    'previous-line-or-history-element)
   (define-key map [XF86Back] 'previous-history-element)
   (define-key map "\es"   'next-matching-history-element)
   (define-key map "\er"   'previous-matching-history-element)

lisp/simple.el

@@ -1984,6 +1984,36 @@ With argument N, it uses the Nth previous element."
   (or (zerop n)
       (goto-history-element (+ minibuffer-history-position n))))
 
+(defun next-line-or-history-element (&optional arg)
+  "Move cursor vertically down ARG lines, or to the next history element.
+When point moves over the bottom line of multi-line minibuffer, puts ARGth
+next element of the minibuffer history in the minibuffer."
+  (interactive "^p")
+  (or arg (setq arg 1))
+  (let ((old-point (point)))
+    (condition-case nil
+	(next-line arg)
+      (end-of-buffer
+       ;; Restore old position since `line-move-visual' moves point to
+       ;; the end of the line when it fails to go to the next line.
+       (goto-char old-point)
+       (next-history-element arg)))))
+
+(defun previous-line-or-history-element (&optional arg)
+  "Move cursor vertically up ARG lines, or to the previous history element.
+When point moves over the top line of multi-line minibuffer, puts ARGth
+previous element of the minibuffer history in the minibuffer."
+  (interactive "^p")
+  (or arg (setq arg 1))
+  (let ((old-point (point)))
+    (condition-case nil
+	(previous-line arg)
+      (beginning-of-buffer
+       ;; Restore old position since `line-move-visual' moves point to
+       ;; the beginning of the line when it fails to go to the previous line.
+       (goto-char old-point)
+       (previous-history-element arg)))))
+
 (defun next-complete-history-element (n)
   "Get next history element which completes the minibuffer before the point.
 The contents of the minibuffer after the point are deleted, and replaced