Form design in preview mode

I’m trying to use the following form design for one controller

form_control.yaml

design:
    displayMode: sidebar
    sidebarSize: default

in the preview.php file I want to display a scoreboard before the form itself

<div class="scoreboard">
    <div data-control="toolbar"><?= $this->makePartial('preview_scoreboard') ?></div>
</div>

<div class="form-preview">
        <?= $this->formRenderDesign() ?>
    </div>

with that, the scoreboard is rendered after the form, at the very bottom of the page instead of before.

Is this a bug ?

@daft