Allows to display custom partials in the header of the Order Preview page in the Administration Area.
The event handler should accept two parameters - the controller object and the order object.
public function subscribeEvents()
{
Backend::$events->addEvent('shop:onExtendOrderPreviewHeader', $this, 'extend_order_preview_header');
}
public function extend_order_preview_header($controller, $order)
{
$controller->renderPartial(PATH_APP.'/modules/mymodule/partials/_orders_preview_header.htm');
}