There is a problem with $_GET and $HTTP_GET_VARS. In documentation, in Predefined Variables is mentioned:

"$HTTP_GET_VARS contains the same information, but is not an autoglobal."

That's true only in one condition - when we are talking about REAL variables passed by GET. But when we set one variable explicity in $HTTP_GET_VARS it is doesn't set in $_GET and vice versa, ie:

$HTTP_GET_VARS["sthnew"] = "some str";
echo $_GET["sthnew"]; // There is no such index

And:

$_GET["sthnew"] = "some str";
echo $HTTP_GET_VARS["sthnew"]; // There is no such index

but !!

$HTTP_SESSION_VARS["sthnew"] = "some str";
echo $_SESSION["sthnew"]; // Everything is OK

I know that _GET and HTTP_GET_VARS shouldn't be set explicity, but I'm doing sth like URL coding and decoding to hide variables from being watched by users and I'm coding also session id. After decoding I write session sid in HTTP_GET_VARS and call session_start(). But session_start() use _only_ $_GET array, not $HTTP_GET_VARS and of course sessions doesn't work. 

I think you should change documentation or change this feature :) When I read: "$HTTP_GET_VARS contains the same information..." it means for me THE SAME ALL THE TIME... If it doesn't it is very confusing :( Especially that $_SESSION and $HTTP_SESSION_VARS contains the same information all the time.

Adam