Issue #1303412 by nod_, droplet: Fixed 'Manage display' : Cannot drag in or out of 'Hidden'.

core/modules/field_ui/field_ui.js

@@ -175,7 +175,7 @@ Drupal.fieldUIOverview = {
     var row = dragObject.rowObject.element;
     var $row = $(row);
     var rowHandler = $row.data('fieldUIRowHandler');
-    if (typeof rowHandler === 'undefined') {
+    if (typeof rowHandler !== 'undefined') {
       var regionRow = $row.prevAll('tr.region-message').get(0);
       var region = regionRow.className.replace(/([^ ]+[ ]+)*region-([^ ]+)-message([ ]+[^ ]+)*/, '$2');
 
@@ -330,7 +330,7 @@ Drupal.fieldUIDisplayOverview.field.prototype = {
       if (currentValue === 'hidden') {
         // Restore the formatter back to the default formatter. Pseudo-fields do
         // not have default formatters, we just return to 'visible' for those.
-        value = (typeof this.defaultFormatter !== 'undefined') ? this.defaultFormatter : 'visible';
+        value = (typeof this.defaultFormatter !== 'undefined') ? this.defaultFormatter : this.$formatSelect.find('option').val();
       }
     }
     else {