Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.368
diff -u -p -r1.368 form.inc
--- includes/form.inc	29 Aug 2009 16:30:14 -0000	1.368
+++ includes/form.inc	1 Sep 2009 22:04:22 -0000
@@ -1637,7 +1637,20 @@ function theme_fieldset($element) {
   }
   $element['#attributes']['id'] = $element['#id'];
 
-  return '<fieldset' . drupal_attributes($element['#attributes']) . '>' . ($element['#title'] ? '<legend>' . $element['#title'] . '</legend>' : '') . (isset($element['#description']) && $element['#description'] ? '<div class="fieldset-description">' . $element['#description'] . '</div>' : '') . (!empty($element['#children']) ? $element['#children'] : '') . (isset($element['#value']) ? $element['#value'] : '') . "</fieldset>\n";
+  $legend_class = '';
+
+  if (!empty($element['#show_legend'])) {
+    $legend_class = ' class="element-invisible"';
+  }
+
+  $output = '<fieldset' . drupal_attributes($element['#attributes']) . '>';
+  $output .= ($element['#title'] ? '<legend' . $legend_class . '>' . $element['#title'] . '</legend>' : '');
+  $output .= (isset($element['#description']) && $element['#description'] ? '<div class="fieldset-description">' . $element['#description'] . '</div>' : '');
+  $output .= (!empty($element['#children']) ? $element['#children'] : '');
+  $output .= (isset($element['#value']) ? $element['#value'] : '');
+  $output .= "</fieldset>\n";
+
+  return $output;
 }
 
 /**
Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.784
diff -u -p -r1.784 system.module
--- modules/system/system.module	1 Sep 2009 16:50:12 -0000	1.784
+++ modules/system/system.module	1 Sep 2009 22:04:22 -0000
@@ -371,8 +371,9 @@ function system_elements() {
   $type['radios'] = array(
     '#input' => TRUE,
     '#process' => array('form_process_radios'),
-    '#theme_wrappers' => array('radios'),
+    '#theme_wrappers' => array('radios', 'fieldset'),
     '#pre_render' => array('form_pre_render_conditional_form_element'),
+    '#show_legend' => TRUE,
   );
 
   $type['radio'] = array(
@@ -388,8 +389,9 @@ function system_elements() {
     '#input' => TRUE,
     '#tree' => TRUE,
     '#process' => array('form_process_checkboxes'),
-    '#theme_wrappers' => array('checkboxes'),
+    '#theme_wrappers' => array('checkboxes', 'fieldset'),
     '#pre_render' => array('form_pre_render_conditional_form_element'),
+    '#show_legend' => TRUE,
   );
 
   $type['checkbox'] = array(
@@ -422,7 +424,8 @@ function system_elements() {
     '#element_validate' => array('date_validate'),
     '#process' => array('form_process_date'),
     '#theme' => 'date',
-    '#theme_wrappers' => array('form_element'),
+    '#theme_wrappers' => array('fieldset'),
+    '#show_legend' => TRUE,
   );
 
   $type['file'] = array(