Index: pollfield.module
===================================================================
--- pollfield.module	(revision 232)
+++ pollfield.module	(working copy)
@@ -93,9 +93,15 @@
  * @return unknown
  */
 function theme_pollfield($element) {
-
-  $output = '<fieldset class="menu-item-form collapsible collapsed pollfield-form"><legend>Pollfield settings</legend>'. $element['#children'] .'</fieldset>';
-  return $output;
+  $fieldset = array(
+    '#type' => 'fieldset',
+    '#title' => $element['#title'],
+    '#collapsible' => TRUE,
+    '#collapsed' => TRUE,
+    '#attributes' => array('class' => 'pollfield-form'),
+    '#children' => $element['#children'],
+  );
+  return theme('fieldset', $fieldset);
 }
 
 /**