Thanks Jason.
At the moment, the default action="<?php echo (htmlentities($_SERVER["PHP_SELF"], ENT_QUOTES)); ?>".
I have to replace it with this as provided by you (thanks):
action="<?php echo (htmlentities($_SERVER["PHP_SELF"], ENT_QUOTES)); ?><?php echo (isset($_SERVER["QUERY_STRING"]) && $_SERVER["QUERY_STRING"] != ""?"?".htmlentities($_SERVER["QUERY_STRING"], ENT_QUOTES):""); ?>"
Is this something that will be fixed in the next update?