diff --git a/runtime/doc/gui_w32.txt b/runtime/doc/gui_w32.txt
index b92a693..17ed69a 100644
--- a/runtime/doc/gui_w32.txt
+++ b/runtime/doc/gui_w32.txt
@@ -1,4 +1,4 @@
-*gui_w32.txt*   For Vim version 7.1.  Last change: 2007 May 03
+*gui_w32.txt*   For Vim version 7.1.  Last change: 2007 Aug 14
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -53,6 +53,16 @@
 There is a specific version of gvim.exe that runs under the Win32s subsystem
 of Windows 3.1 or 3.11.  See |win32s|.
 
+
+Using Vim as a plugin					*gui-w32-windowid*
+
+When gvim starts up normally, it creates its own top level window.  If you
+pass Vim the command-line option |--windowid| with a decimal or hexadecimal
+value, Vim will create a window that is a child of the window with the given
+ID.  This enables Vim to act as a plugin in another application.  This really
+is a programmer's interface, and is of no use without a supporting application
+to spawn Vim correctly.
+
 ==============================================================================
 2. Vim as default editor				*vim-default-editor*