src/Extensions/GridFieldBetterButtonsItemRequest.php
public function getPreviousRecordID()
    {
        $map = $this->owner->gridField->getManipulatedList()->limit(PHP_INT_MAX, 0)->column('ID');
        $offset = array_search($this->owner->record->ID, $map);
        return isset($map[$offset-1]) ? $map[$offset-1] : false;
    }
public function getPreviousRecordID()
    {
        $map = $this->owner->gridField->getManipulatedList()->limit(PHP_INT_MAX, 0)->column('ID');
        $offset = array_search($this->owner->record->ID, $map);
        return isset($map[$offset-1]) ? $map[$offset-1] : false;
    }
Gets the ID of the previous record in the list.
WARNING: This does not respect the mutated state of the list (e.g. sorting or filtering).
Currently the GridField API does not expose this in the detail form view.

@todo  This method is very inefficient.
@return int