--- laboratory/Zend/Form/Element/Multi.php.dist	2008-01-07 19:53:25.000000000 +0100
+++ laboratory/Zend/Form/Element/Multi.php	2008-01-07 20:29:57.000000000 +0100
@@ -47,6 +47,12 @@
     protected $_separator = '<br />';
 
     /**
+     * Array of multi-item-specific errors
+     * @var array
+     */
+    protected $_multi_errors = array();
+
+    /**
      * Retrieve separator
      *
      * @return mixed
@@ -112,5 +118,29 @@
         $this->_options = array();
         return $this;
     }
-}
 
+    /**
+     * Retrieve validation errors, if any
+     * 
+     * @return array
+     */
+    public function getErrors()
+    {
+        return $this->_multi_errors + $this->getValidatorChain()->getMessages();
+    }
+
+    /**
+     * Validate element
+     *
+     * @param  mixed $value
+     * @return bool
+     */
+    public function isValid($value = null)
+    {
+        if (! isset($this->_options[$value])) {
+            $this->_multi_errors[] = 'Chosen value is not available';
+            return false;
+        }
+        return $this->getValidatorChain()->isValid($value);
+    }
+}