I would like to understand this too.
I’m using add_action(‘edit_form_advanced’,’hookfunction’) for this propose and for displaying it where I want I use js:
var prephtml= '<div>'+ jQuery('#newfield').html()+ '</div>'
jQuery('#newfield').html('')
jQuery('#postdivrich').prepend(prephtml)
Not happy at all about this workaround, this must be an easier task.