Hi,
if you one broken link more times in $Content, e.g. like:
<p><a href="xxx/">first</a> ... <a href="xxx/">second</a></p>
then, after a few times of reading the content and saving in CMS, thre is an attribute class="broken broken broken ...".
I have changed the Field() method in HtmlEditorField.php to avoid this:
// Mark up broken links
if ($links) {
$links = array_unique($links);
foreach($links as $link) {
...