<fieldset style="margin:5px; border:1px dashed #666666;">

  <legend>Look Up Extension</legend>

  Search: <input style="width: 250px;" type="text" onkeyup="post('<?=$base_url?>/files/ext/post.php', 'action=lookup_ext&str='+this.value, 'ext_lookup_results', 0);" />

</fieldset>

<div id="ext_lookup_results"></div>