diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 1a44a68..c599e8a 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -1,4 +1,4 @@
-*eval.txt*	For Vim version 7.3.  Last change: 2011 Feb 07
+*eval.txt*	For Vim version 7.3.  Last change: 2011 Feb 11
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -1286,7 +1286,9 @@
 
 					*v:beval_winnr* *beval_winnr-variable*
 v:beval_winnr	The number of the window, over which the mouse pointer is. Only
-		valid while evaluating the 'balloonexpr' option.
+		valid while evaluating the 'balloonexpr' option.  The first
+		window has number zero (unlike most other places where a
+		window gets a number).
 
 					*v:char* *char-variable*
 v:char		Argument for evaluating 'formatexpr' and used for the typed