Now that WordPress has updated to version 3.5, the media gallery has been overhauled and this custom options solution doesn’t appear to work anymore. I’d like to add a couple of fields to the gallery, so that a client doesn’t have to manually add these fields to the gallery shortcode.
Does anyone know how to add custom fields with the new 3.5 gallery?
It looks like the nightly builds of the Advanced Custom Fields plugin can (mostly) handle this now, so you could try installing that. Details on this support issue.
I can’t update my copy of it to test right now but this is what it would look like in the admin: