It's 'display' that is not inheritable, not 'visibility'.
--- a/master/painting.html Tue May 22 13:20:55 2012 +1000
+++ b/master/painting.html Tue May 22 13:22:04 2012 +1000
@@ -1163,7 +1163,7 @@
to <span class="prop-value">hidden</span> on a <a>'g'</a>
will make its children invisible as long as the children do
not specify their own <a>'visibility'</a> properties as <span
-class="prop-value">visible</span>. Note that <a>'visibility'</a> is
+class="prop-value">visible</span>. Note that <a>'display'</a> is
<em>not</em> an inheritable property.</p>
<p>When the <a>'display'</a> property is set to <span