Is it possible to have a custom metabox with the ability to either:
- enter a new meta_value in a certain meta_key OR
- choose from a list of the existing meta_keys, from a dropdown/select-box, autocomplete/suggestions or anything else
(basically, the way category and tag meta-boxes work, only with custom fields not custom taxonomies)
Graphically, the box should look like this:
Can this be done with an existing plugin or code / how?