Fixed session key clearing process, it should work right now.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>{#advanced_dlg.link_title}</title>
<script type="text/javascript" src="../../tiny_mce_popup.js"></script>
<script type="text/javascript" src="../../utils/mctabs.js"></script>
<script type="text/javascript" src="../../utils/form_utils.js"></script>
<script type="text/javascript" src="../../utils/validate.js"></script>
<script type="text/javascript" src="js/link.js"></script>
<base target="_self" />
</head>
<body id="link" style="display: none">
<form onsubmit="LinkDialog.update();return false;" action="#">
<div class="tabs">
<ul>
<li id="general_tab" class="current"><span><a href="javascript:mcTabs.displayTab('general_tab','general_panel');" onmousedown="return false;">{#advanced_dlg.link_title}</a></span></li>
</ul>
</div>
<div class="panel_wrapper">
<div id="general_panel" class="panel current">
<table border="0" cellpadding="4" cellspacing="0">
<tr>
<td nowrap="nowrap"><label for="href">{#advanced_dlg.link_url}</label></td>
<td><table border="0" cellspacing="0" cellpadding="0">
<tr>
<td><input id="href" name="href" type="text" class="mceFocus" value="" style="width: 200px" onchange="LinkDialog.checkPrefix(this);" /></td>
<td id="hrefbrowsercontainer"> </td>
</tr>
</table></td>
</tr>
<tr>
<td><label for="link_list">{#advanced_dlg.link_list}</label></td>
<td><select id="link_list" name="link_list" onchange="document.getElementById('href').value=this.options[this.selectedIndex].value;"></select></td>
</tr>
<tr>
<td><label id="targetlistlabel" for="targetlist">{#advanced_dlg.link_target}</label></td>
<td><select id="target_list" name="target_list"></select></td>
</tr>
<tr>
<td nowrap="nowrap"><label for="linktitle">{#advanced_dlg.link_titlefield}</label></td>
<td><input id="linktitle" name="linktitle" type="text" value="" style="width: 200px" /></td>
</tr>
<tr>
<td><label for="class_list">{#class_name}</label></td>
<td><select id="class_list" name="class_list"></select></td>
</tr>
</table>
</div>
</div>
<div class="mceActionPanel">
<div style="float: left">
<input type="submit" id="insert" name="insert" value="{#insert}" />
</div>
<div style="float: right">
<input type="button" id="cancel" name="cancel" value="{#cancel}" onclick="tinyMCEPopup.close();" />
</div>
</div>
</form>
</body>
</html>