test better detail combined view

app/UI/VmUpdate/Sections/Qemu/AdditionalDiskSection.php

@@ -27,7 +27,7 @@ class AdditionalDiskSection extends BaseSection implements ClientArea
         $this->initIds('additionalDiskSection');
         $this->initFields();
         $this->loadAdditionalDisks();
-        $diskSize = $this->getFormData()['size'];
+        $diskSize = $this->getData('additionalDiskSize');
         $rangeField = $this->getField('additionalDiskSize');
         $rangeField->setMinValue($diskSize);
         $rangeField->setDefaultValue($diskSize);