How to open WordPress media create/edit Gallery Dialog

The question is a few months old but still can help someone.

To open the media uploader to the “edit gallery” view, you just have to set the state to “gallery-edit” like this :

media_uploader = wp.media({
    frame:    "post",
    state:    "gallery-edit", // here
    multiple: true,
    editing:  true,
});

For now, I still can’t figure out how to set a default selected gallery on the opening, when you want to edit a gallery already created. If someone knows how to do this. Thanks!