change test to slider for disk create

app/UI/Disk/Forms/UpdateForm.php

@@ -38,6 +38,7 @@ class UpdateForm extends BaseForm implements ClientArea
 
     public function initContent()
     {
+        parent::initContent();
         $this->initIds('updateDiskForm');
         $this->setFormType('update');
         $this->setProvider(new DiskProvider());
@@ -61,6 +62,7 @@ class UpdateForm extends BaseForm implements ClientArea
 
     private function initFields()
     {
+        parent::initContent();
         //entity id
         $this->addField(new Hidden("id"));
         //size