Index: modules/field/modules/text/text.js
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/modules/text/text.js,v
retrieving revision 1.4
diff -u -p -r1.4 text.js
--- modules/field/modules/text/text.js	12 Jun 2010 08:18:59 -0000	1.4
+++ modules/field/modules/text/text.js	14 Oct 2010 06:22:44 -0000
@@ -38,7 +38,7 @@ Drupal.behaviors.textSummary = {
         ).appendTo($summaryLabel);
 
         // If no summary is set, hide the summary field.
-        if ($(this).val() == '') {
+        if ($(this).find('.text-summary').val() == '') {
           $link.click();
         }
         return;
Index: modules/field/modules/text/text.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/modules/text/text.module,v
retrieving revision 1.65
diff -u -p -r1.65 text.module
--- modules/field/modules/text/text.module	18 Sep 2010 02:18:35 -0000	1.65
+++ modules/field/modules/text/text.module	14 Oct 2010 06:22:44 -0000
@@ -171,7 +171,12 @@ function text_field_load($entity_type, $
  */
 function text_field_is_empty($item, $field) {
   if (empty($item['value']) && (string) $item['value'] !== '0') {
-    return TRUE;
+    if ($field['type'] == 'text_with_summary') {
+      return (empty($item['summary']) && (string)$item['summary'] !== '0');
+    }
+    else {
+      return TRUE;
+    }
   }
   return FALSE;
 }