diff --git a/doc/config.html b/doc/config.html
index c08fef7f..e5ac2c9a 100755
--- a/doc/config.html
+++ b/doc/config.html
@@ -877,13 +877,19 @@ if the file name starts with a <b><code>"/"</code></b> (Unix) or <b><code>
         This value sets the number of characters per line of the main message
         entry field. The default value is 76 (78 for replies), and can be
         increased for installations which need a larger window size (like
-        pasting log files etc.).
+        pasting log files etc.). If both <code><b>Message Width</b></code>
+        and <code><b>Message Height</b></code> are not given, some JavaScript
+        code is used which automatically resizes the message window
+        dynamically to fit optimally into the browser window.
       </li>
       <li>
         <b><code>Message Height = &lt;number&gt;</code></b><br>
         This value sets the number of lines of the main message entry field.
         The default value is 20, and can be changed for installations which
-        need a different window size.
+        need a different window size. If both <code><b>Message Width</b></code>
+        and <code><b>Message Height</b></code> are not given, some JavaScript
+        code is used which automatically resizes the message window
+        dynamically to fit optimally into the browser window.
       </li>
       <li>
         <b><code>Admin textarea = &lt;cols&gt;,&lt;rows&gt;</code></b><br>