When using the "manual" method, I've disabled the external method of

changing passwords, and enabled the internal "change password" button
just like "email" and "none".

Thanks to Danilo Massa for pointing out the inconsistency.

admin/auth.php

@@ -113,7 +113,7 @@
 
     require_once("$CFG->dirroot/auth/$auth/config.html");
 
-    if ($auth != "email" and $auth != "none") {
+    if ($auth != "email" and $auth != "none" and $auth != "manual") {
         echo "<tr valign=\"top\">";
 	    echo "<td align=right nowrap><p>";
         print_string("changepassword", "auth");