Index: text_captcha/word_list_captcha/word_list_captcha.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/captcha_pack/text_captcha/word_list_captcha/word_list_captcha.module,v
retrieving revision 1.12
diff -u -p -r1.12 word_list_captcha.module
--- text_captcha/word_list_captcha/word_list_captcha.module	7 Apr 2008 22:55:03 -0000	1.12
+++ text_captcha/word_list_captcha/word_list_captcha.module	11 Nov 2010 00:31:53 -0000
@@ -78,16 +78,7 @@ function word_list_captcha_captcha($op, 
           '#options' => $options,
           // extra class needed for additional CSS'ing of the options
           '#attributes' => array('class' => 'text-captcha-word-list-radios'),
-          // TODO: the following needs to be ported to Drupal 6, which does not
-          // support DANGEROUS_SKIP_CHECK anymore
-          //
-          // The following entry '#DANGEROUS_SKIP_CHECK' is needed to prevent
-          // that Drupal checks during validation phase if a submitted option
-          // is in the list of possible options. (see includes/form.inc)
-          // The options are randomly generated on each call and consequently
-          // almost never the same during the generate phase and the validation
-          // phase.
-          '#DANGEROUS_SKIP_CHECK' => TRUE, //
+          '#after_build' => array('_word_list_captcha_validate_response'),
           '#required' => TRUE,
         );
         // additional text CAPTCHA CSS rules
@@ -97,3 +88,25 @@ function word_list_captcha_captcha($op, 
       break;
   }
 }
+
+/**
+ * #after_build handler for captcha_response element.
+ *
+ * Because the options are randomly generated (and consequently almost
+ * never the same at validation as they were during the initial
+ * generation), the following #after_build step is used to prevent
+ * Drupal's validation from rejecting the submitted value with 'An
+ * illegal choice has been detected' if it does not appear in the new
+ * set of options.
+ */
+function _word_list_captcha_validate_response($element, &$form_state) {
+  if (array_key_exists('#value', $element)) {
+    if ($value = $element['#value']) {
+      $options =& $element['#options'];
+      if (!array_key_exists($value, $options)) {
+        $options[$value] = $value;
+      }
+    }
+  }
+  return $element;
+}