URL sanitizer: disabled uppercase letters in URL hex character codes (it was causing conflicts with the Windows/Apache 2.2 alt namespace separator). Thanks Techokami for finding and reporting this bug.
<!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.anchor_title}</title>
<script type="text/javascript" src="../../tiny_mce_popup.js"></script>
<script type="text/javascript" src="js/anchor.js"></script>
</head>
<body style="display: none">
<form onsubmit="AnchorDialog.update();return false;" action="#">
<table border="0" cellpadding="4" cellspacing="0">
<tr>
<td colspan="2" class="title">{#advanced_dlg.anchor_title}</td>
</tr>
<tr>
<td class="nowrap">{#advanced_dlg.anchor_name}:</td>
<td><input name="anchorName" type="text" class="mceFocus" id="anchorName" value="" style="width: 200px" /></td>
</tr>
</table>
<div class="mceActionPanel">
<div style="float: left">
<input type="submit" id="insert" name="insert" value="{#update}" />
</div>
<div style="float: right">
<input type="button" id="cancel" name="cancel" value="{#cancel}" onclick="tinyMCEPopup.close();" />
</div>
</div>
</form>
</body>
</html>