Bunu dene bakalım.
<div class="search fleft">
<form name="QuickSearchFrom" action="http://www.xxx.com/index.php?do=catalog/exec&ref=search" method="POST">
<?php if ($filter_name) { ?>
<input type="hidden" name="filter_name" value="<?php echo $filter_name; ?>" />
<input type="text"...