Magento Widget XML/HTML Entities 500 Error Fix

Mage_Widget_Helper_Data.php

<?php
class Mage_Widget_Helper_Data extends Mage_Core_Helper_Abstract
{
    /**
     * Further refine escaped HTML.
     */
    public function escapeHtml($data, $allowedTags = null)
    {
        $parent = parent::escapeHtml($data, $allowedTags);

        if (is_array($parent)) {
            $result = array();
            foreach ($parent as $item) {
                $result[] = $this->escapeHtml($item);
            }
        } else {
            // process single item
            if (strlen($parent)) {                
                $result = preg_replace('/\&(?!(?:amp|lt|gt|#039|quot);)[^ ;]+;/', "<![CDATA[\\0]]>", $parent);
            } else {
                $result = $parent;
            }
        }
        
        return $result;
    }
}