Index: form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.157
diff -u -r1.157 form.inc
--- form.inc	20 Oct 2006 20:55:03 -0000	1.157
+++ form.inc	29 Oct 2006 14:26:34 -0000
@@ -843,7 +843,10 @@
   }
 
   foreach ($array as $key => $value) {
-    if (is_array($value)) {
+    if (is_object($value)) {
+      form_options_flatten($value->option, FALSE);
+    }
+    else if (is_array($value)) {
       form_options_flatten($value, FALSE);
     }
     else {