'upload_dir' and 'image_pload' Field

Hi

I want to be able to use the 'upload_dir' in the 'image_upload' field type. I do realise that it does not work. What I am after is the look of the 'image_upload' field in terms of the drag and drop image sorting and multiple file uploads.

So I performed a test with the 'image' field below and it turns out the 'upload_dir' does work for this field too. Even though its not in the docs. So I could use this field but how would I go about adding the image preview and drag and drop support to this?

array(
    'name'             => 'Images',
    'id'               => 'images',
    'type'             => 'image',
    'force_delete'     => true,
    'max_file_uploads' => 6,
    'upload_dir' => WP_CONTENT_DIR . '/test/',
),

I guess if this is not possible then looking from this post https://support.metabox.io/topic/changing-upload-dir-for-file-field/ it looks like I will have to wait for the feature to be included. Any news on this?