Theme Inheritance with Quark theme and 1.4.0-beta.3

Got the same problem, and even with this fix it does not change , i still have a blank html with only my content but not the style. I was with antimatter before and want to switch my inheritance to quark. I tried to put directly quark and it’s working.

Here is my mytheme.php :

<?php
namespace Grav\Theme;
use Grav\Common\Theme;
// class Mytheme extends Antimatter
class Mytheme extends Quark
{
   // Some new methods, properties etc.
}
?>

and my mytheme.yaml :

streams:
 schemes:
   theme:
     type: ReadOnlyStream
     prefixes:
       '':
         - user/themes/mytheme
         # - user/themes/antimatter
         - user/themes/quark 

Any idea ? Thanks in advance !