With the following in MediaWiki:Edittools:

<charinsert> € £ ¥ $ ¢ © ® ™ </charinsert> ·
<charinsert> « + » {{+}} </charinsert>
<charinsert> — – ‘ “ ’ ” | … ~ # @ § ¶ • ¡ ¿ \ </charinsert>

I get the following HTML output (see second line) on all edit pages:

<a onclick="insertTags(&#39;«&#39;,&#39;&#39;,&#39;&#39;);return false" href="#">«</a>
<a onclick="insertTags(&#39;&#39;,&#39;&#39;,&#39;&#39;);return false" href="#" />
<a onclick="insertTags(&#39;»&#39;,&#39;&#39;,&#39;&#39;);return false" href="#">»</a>

Which triggers the following DOM error in WebKit:

• XML self-closing tag syntax used on <a>. The tag will not be closed.

And in the end result, it doesn't work. (unclickable ofcourse).

The HTML output when viewing the message-page is slightly different:

<a onclick="insertTags('«','','');return false" href="#">«</a>
<a onclick="insertTags('','','');return false" href="#"></a>
<a onclick="insertTags('»','','');return false" href="#">»</a>

Version: unspecified
Severity: major