Returns the region to which a row in the 'Manage display' screen belongs.
This function is used as a #region_callback in field_ui_field_overview_form(), and is called during field_ui_table_pre_render().
function field_ui_display_overview_row_region($row) {
switch ($row['#row_type']) {
case 'field':
case 'extra_field':
return $row['format']['type']['#value'] == 'hidden' ? 'hidden' : 'visible';
}
}