Simply use this code to echo the current URL in to the action field of the login form...

<form name="LsLogin" action="<?php echo "http://{$_SERVER['HTTP_HOST']}{$_SERVER['REQUEST_URI']}"; ?>" method="POST">

Sorry if I seem persistent but assuming this works It should make a few people happier.

Also, bear in mind that I'm only going by assumption on how your base code works, from a frontend perspective.