Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.265
diff -u -r1.265 form.inc
--- includes/form.inc	4 Feb 2008 10:23:32 -0000	1.265
+++ includes/form.inc	5 Feb 2008 00:25:10 -0000
@@ -661,14 +661,18 @@
       _form_validate($elements[$key], $form_state);
     }
   }
+
   // Validate the current input.
   if (!isset($elements['#validated']) || !$elements['#validated']) {
     if (isset($elements['#needs_validation'])) {
-      // We only check for trimmed string length being zero. 0 might be
-      // a possible value with some field types, such as radio buttons, so
-      // empty() is not usable here.
-      if ($elements['#required'] && strlen(trim($elements['#value'])) == 0) {
-        form_error($elements, $t('!name field is required.', array('!name' => $elements['#title'])));
+
+      // Validate required form items:
+      // Count() checks if the item (string, array, integer) contains anything.
+      // Beyond that, strings are checked not to be empty after being trimmed.
+      if ($elements['#required']) {
+        if ((!count($elements['#value']) || (is_string($elements['#value']) && strlen(trim($elements['#value'])) == 0))) {
+          form_error($elements, $t('!name field is required.', array('!name' => $elements['#title'])));
+        }
       }
 
       // Verify that the value is not longer than #maxlength.