Grid Field Detail Form that has a search sidebar always visible. Note that we just need to modify the item_request, not the whole GridFieldDetailForm. Usage:

class MyDataObjectAdmin extends ModelAdmin {

	static $managed_models = array(
	    'MyDataObject'
	);

	public function getEditForm($id = null, $fields = null) {
	    $form = parent::getEditForm($id, $fields);
	    $config = $form->Fields()->first()->getConfig();
	    $config->getComponentByType('GridFieldDetailForm')
	            ->setItemRequestClass('GridFieldDetailFormWithSearch_ItemRequest')
	            ->setTemplate('GridFieldDetailFormWithSearch');
	    return $form;
	}

}