This fails validation if an uploaded file is present.
The validation rule:
$val->add_field('design_file', '"File for Upload"', 'required');
From the view:
<?php
echo Form::label('File for Upload', 'design_file');
echo Form::input(array('type' => 'file', 'name' => 'design_file'));
?>
Am I doing something wrong or is this a bug?
I don't think you can validated an form field of type 'file', as it will not be part of $_POST, it will be part of $_FILES.
Use the Upload class to validate and process uploaded files.