--- a/lisp/prim/help.el	Mon Aug 13 08:53:21 2007 +0200
+++ b/lisp/prim/help.el	Mon Aug 13 08:53:38 2007 +0200
@@ -349,7 +349,8 @@
 the window.")
 
 (defvar help-window-config nil)
-
+(defvar help-window-max-height .5
+  "*Proportion of frame to use for help windows.")
 ;; Use this function for displaying help when C-h something is pressed
 ;; or in similar situations.  Do *not* use it when you are displaying
 ;; a help message and then prompting for input in the minibuffer --
@@ -384,6 +385,11 @@
                      (message
                       (substitute-command-keys "Type \\[switch-to-buffer-other-window] to restore the other window, \\[scroll-other-window] to scroll the help."))))
 	      (when temp-buffer-shrink-to-fit
+		(let* ((help-window-size (round (* help-window-max-height
+					    (frame-height (window-frame helpwin)))))
+		       (size (window-displayed-height helpwin)))
+		  (if (< size help-window-size)
+		      (enlarge-window (- help-window-size size) nil helpwin)))
 		(shrink-window-if-larger-than-buffer helpwin))))))))
 
 (defun describe-key (key)