Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.1098
diff -u -p -r1.1098 common.inc
--- includes/common.inc	5 Feb 2010 21:15:43 -0000	1.1098
+++ includes/common.inc	5 Feb 2010 23:14:51 -0000
@@ -5695,6 +5695,9 @@ function drupal_common_theme() {
     'vertical_tabs' => array(
       'render element' => 'element',
     ),
+    'vertical_tabs_fieldset' => array(
+      'render element' => 'element',
+    ),
     'container' => array(
       'render element' => 'element',
     ),
Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.430
diff -u -p -r1.430 form.inc
--- includes/form.inc	4 Feb 2010 03:34:20 -0000	1.430
+++ includes/form.inc	5 Feb 2010 23:14:53 -0000
@@ -1964,6 +1964,36 @@ function theme_fieldset($variables) {
 }
 
 /**
+ * Theme a fieldset form element wrapped for a vertical tab group.
+ *
+ * This is an internal function that is added by form_pre_render_vertical_tabs()
+ * to the #theme_wrapper attribute of fieldsets that are inside vertical tab groups.
+ *
+ * @param $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ *     Properties used: #attributes, #children, #collapsed, #collapsible,
+ *     #description, #id, #title, #value.
+ *
+ *  * @return
+ *   A themed HTML string representing the group of items.
+ */
+function theme_vertical_tabs_fieldset($variables) {
+  $element = $variables['element'];
+
+  $output = '<div class="fieldset-wrapper">';
+  if (isset($element['#content_prefix'])) {
+    $output .= $element['#content_prefix'];
+  }
+  $output .= theme('fieldset', $variables);
+  if (isset($element['#content_suffix'])) {
+    $output .= $element['#content_suffix'];
+  }
+  $output .= '</div>';
+  return $output;
+}
+
+/**
  * Theme a radio button form element.
  *
  * @param $variables
@@ -2717,6 +2747,40 @@ function form_process_vertical_tabs($ele
 }
 
 /**
+ * Adds theme wrapper to fieldsets contained in a vertical tab group
+ * and moves prefix or suffix attributes to be handled by the theme wrapper
+ * instead of drupal_render().
+ *
+ * @param $element
+ *   An associative array containing the properties and children of the
+ *   vertical tab group.
+ *
+ * @return
+ *   The modified element with all group members.
+ */
+function form_pre_render_vertical_tabs($element) {
+  $parents = implode('][', $element['group']['#parents']);
+  $children = element_children($element['group']['#groups'][$parents]);
+  if (!empty($children)) {
+    foreach ($children as $key) {
+      $child = $element['group']['#groups'][$parents][$key];
+      if (is_array($child) && $child['#type'] === 'fieldset') {
+        if (isset($child['#prefix'])) {
+          $element['group']['#groups'][$parents][$key]['#content_prefix'] = $child['#prefix'];
+          unset($element['group']['#groups'][$parents][$key]['#prefix']);
+        }
+        if (isset($child['#suffix'])) {
+          $element['group']['#groups'][$parents][$key]['#content_suffix'] = $child['#suffix'];
+          unset($element['group']['#groups'][$parents][$key]['#suffix']);
+        }
+        $element['group']['#groups'][$parents][$key]['#theme_wrappers'][] = 'vertical_tabs_fieldset';
+      }
+    }
+  }
+  return $element;
+}
+
+/**
  * Makes the element's children fieldsets be vertical tabs.
  *
  * @param $variables
Index: misc/vertical-tabs.css
===================================================================
RCS file: /cvs/drupal/drupal/misc/vertical-tabs.css,v
retrieving revision 1.6
diff -u -p -r1.6 vertical-tabs.css
--- misc/vertical-tabs.css	31 May 2009 00:51:41 -0000	1.6
+++ misc/vertical-tabs.css	5 Feb 2010 23:14:53 -0000
@@ -15,12 +15,12 @@ div.vertical-tabs ul.vertical-tabs-list 
   left: -15em;
   float: left;
 }
-div.vertical-tabs .vertical-tabs-panes fieldset.vertical-tabs-pane {
+div.vertical-tabs .vertical-tabs-panes div.vertical-tabs-pane {
   margin: 0 !important;
   padding: 0 1em;
   border: 0;
 }
-div.vertical-tabs .vertical-tabs-panes fieldset.vertical-tabs-pane legend {
+div.vertical-tabs .vertical-tabs-panes div.vertical-tabs-pane legend {
   display: none;
 }
 
Index: misc/vertical-tabs.js
===================================================================
RCS file: /cvs/drupal/drupal/misc/vertical-tabs.js,v
retrieving revision 1.7
diff -u -p -r1.7 vertical-tabs.js
--- misc/vertical-tabs.js	31 Aug 2009 05:51:08 -0000	1.7
+++ misc/vertical-tabs.js	5 Feb 2010 23:14:53 -0000
@@ -23,13 +23,13 @@ Drupal.behaviors.verticalTabs = {
       $(this).wrap('<div class="vertical-tabs clearfix"></div>').before(list);
 
       // Transform each fieldset into a tab.
-      $('> fieldset', this).each(function () {
-        var tab = new Drupal.verticalTab({ title: $('> legend', this).text(), fieldset: $(this) });
+      $('> div.fieldset-wrapper', this).each(function () {
+        var tab = new Drupal.verticalTab({ title: $('fieldset:first > legend', this).text(), fieldsetWrapper: $(this) });
         list.append(tab.item);
         $(this)
-          .removeClass('collapsible collapsed')
           .addClass('vertical-tabs-pane')
           .data('verticalTab', tab);
+        $('fieldset', this).removeClass('collapsible collapsed');
         if (this.id == focusID) {
           focus = $(this);
         }
@@ -63,7 +63,7 @@ Drupal.verticalTab = function (settings)
     return false;
   });
 
-  this.fieldset
+  this.fieldsetWrapper
     .bind('summaryUpdated', function () {
       self.updateSummary();
     })
@@ -73,23 +73,23 @@ Drupal.verticalTab = function (settings)
 Drupal.verticalTab.prototype = {
   // Displays the tab's content pane.
   focus: function () {
-    this.fieldset
-      .siblings('fieldset.vertical-tabs-pane')
+    this.fieldsetWrapper
+      .siblings('div.vertical-tabs-pane')
         .each(function () {
           var tab = $(this).data('verticalTab');
-          tab.fieldset.hide();
+          tab.fieldsetWrapper.hide();
           tab.item.removeClass('selected');
         })
         .end()
       .show()
       .siblings(':hidden.vertical-tabs-active-tab')
-        .val(this.fieldset.attr('id'));
+        .val(this.fieldsetWrapper.attr('id'));
     this.item.addClass('selected');
   },
 
   // Updates the tab's summary.
   updateSummary: function () {
-    this.summary.html(this.fieldset.getSummary());
+    this.summary.html(this.fieldsetWrapper.find('fieldset:first').getSummary());
   }
 };
 
Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.886
diff -u -p -r1.886 system.module
--- modules/system/system.module	5 Feb 2010 21:20:00 -0000	1.886
+++ modules/system/system.module	5 Feb 2010 23:14:55 -0000
@@ -475,6 +475,7 @@ function system_element_info() {
     '#theme_wrappers' => array('vertical_tabs'),
     '#default_tab' => '',
     '#process' => array('form_process_vertical_tabs'),
+    '#pre_render' => array('form_pre_render_vertical_tabs'),
   );
 
   $types['container'] = array(
Index: themes/garland/style.css
===================================================================
RCS file: /cvs/drupal/drupal/themes/garland/style.css,v
retrieving revision 1.73
diff -u -p -r1.73 style.css
--- themes/garland/style.css	30 Jan 2010 07:59:26 -0000	1.73
+++ themes/garland/style.css	5 Feb 2010 23:14:56 -0000
@@ -888,7 +888,7 @@ fieldset {
 
 /* Keep the background position at 0 for filters and vertical tabs. */
 *:first-child+html fieldset.filter-wrapper,
-*:first-child+html fieldset.vertical-tabs-pane {
+*:first-child+html div.vertical-tabs-pane {
   background-position: 0 0;
 }
 
@@ -932,7 +932,7 @@ div.vertical-tabs {
   border-color: #d9eaf5;
 }
 
-div.vertical-tabs .vertical-tabs-panes fieldset.vertical-tabs-pane {
+div.vertical-tabs .vertical-tabs-panes div.vertical-tabs-pane {
   padding: 0.5em 1em;
 }
 
Index: themes/seven/vertical-tabs.css
===================================================================
RCS file: /cvs/drupal/drupal/themes/seven/vertical-tabs.css,v
retrieving revision 1.4
diff -u -p -r1.4 vertical-tabs.css
--- themes/seven/vertical-tabs.css	11 Jan 2010 06:44:31 -0000	1.4
+++ themes/seven/vertical-tabs.css	5 Feb 2010 23:14:56 -0000
@@ -10,11 +10,17 @@ div.vertical-tabs {
   background: #f8f8f8;
 }
 
-div.vertical-tabs fieldset {
-  border: 0;
+div.vertical-tabs div.vertical-tabs-pane {
   padding: 0 0 0 20px;
 }
 
+div.vertical-tabs div.vertical-tabs-pane fieldset {
+  margin: 0;
+  padding: 0;
+  border: 0;
+  background: transparent;
+}
+
 div.vertical-tabs .vertical-tabs-list {
   line-height: 10px;
   font-size: 11px;