Unable to add strike element to custom configuration

[erashdan]

Hi,

I'm trying to create custom configuration by add strike to PurifySetupProvider as in https://github.com/stevebauman/purify#custom-configuration-rules

I created PurifySetupProvider and I added this line for strike
$def->addElement('strike', 'Block', 'Flow', 'Common');

And still not working,

Did I miss something in configuration ?

[erashdan]

It works by change purify.php from
'HTML.Doctype' => 'XHTML 1.0 Strict',
to
'HTML.Doctype' => 'HTML 4.01 Transitional',