function initiateEditor()
{
          $tableColumns['url'] = array(
               'display_text' => 'URL', 
               'perms' => 'EVCAXTQSFHO',
               'table_fun' => array(&$this,'formatLink'), 
               'view_fun' => array(&$this,'formatLink')
          );
     ...
}

function formatLink($col,$val,$row,$instanceName,$rowNum)
{
     $html = '';
     if(strlen($val) > 0)
     {
          $html = '<a target="_blank" href="'.$val.'">'.$val.'</a>';
     }
     return $html;
}