src/Buttons/BetterButton_New.php
public function shouldDisplay()
    {
         // Do not show create new within create new
        if ($this->gridFieldRequest->getRequest()->param('ID') == 'new') {
            return false;
        }
        return $this->gridFieldRequest->record->canCreate();
    }
public function shouldDisplay()
    {
         // Do not show create new within create new
        if ($this->gridFieldRequest->getRequest()->param('ID') == 'new') {
            return false;
        }
        return $this->gridFieldRequest->record->canCreate();
    }
Determines if the button should show
@return boolean