--- bookmark.el	2015-03-20 14:25:37.325230039 -0400
+++ bookmark-new.el	2015-03-20 14:40:51.425200402 -0400
@@ -1901,9 +1901,20 @@
       (bookmark-bmenu-other-window))))
 
 
+(defvar bookmark-bmenu-toggle-auto-display-annotations nil
+"When not `nil', function `bookmark-bmenu-show-annotation' (by
+default, bound to `a`), toggles whether to automatically display
+a bookmark's annotation as one navigates through the bookmark
+list. Default is `nil'.")
+
 (defun bookmark-bmenu-show-annotation ()
   "Show the annotation for the current bookmark in another window."
   (interactive)
+  (when (and (called-interactively-p "any")
+             bookmark-bmenu-toggle-auto-display-annotations)
+    (if bookmark-bmenu-auto-display-annotations
+      (setq bookmark-bmenu-auto-display-annotations nil)
+     (setq bookmark-bmenu-auto-display-annotations t)))
   (let ((bookmark (bookmark-bmenu-bookmark)))
     (bookmark-show-annotation bookmark)))
 
@@ -2068,6 +2079,31 @@
     (forward-line 1))
   (forward-line 0))
 
+(defvar bookmark-bmenu-auto-display-annotations nil
+"Whether to automatically display a bookmark's annotation as one
+navigates through the bookmark list. `t' for yes. Default is
+`nil'.")
+
+(defvar bookmark-bmenu-last-post-command-line 1
+"The line number at point, within the bookmark list buffer, after
+the last command had been run in that buffer.")
+
+(defun bookmark-bmenu-motion-hook-function ()
+"This function is added to the `post-command-hook' locally for
+bookmark list buffers, in order to update any visible annotations
+as one navigates within the buffer."
+  (let ((annotation-buffer))
+    (when (/= bookmark-bmenu-last-post-command-line (line-number-at-pos))
+      (when (setq annotation-buffer (get-buffer "*Bookmark Annotation*"))
+        (kill-buffer annotation-buffer))
+      (when bookmark-bmenu-auto-display-annotations
+        (bookmark-bmenu-show-annotation)))))
+
+(defun bookmark-bmenu-post-command-hook-function ()
+  (add-hook 'post-command-hook 'bookmark-bmenu-motion-hook-function t t))
+
+(add-hook 'bookmark-bmenu-mode-hook 'bookmark-bmenu-post-command-hook-function)
+
 
 
 ;;; Menu bar stuff.  Prefix is "bookmark-menu".