/**
  * Function used only via ajax to return all completed tasks
  *
  * @param void
  * @return null
  */
 function list_completed()
 {
     if (!$this->request->isAsyncCall()) {
         $this->redirectToReferer('dashboard');
     }
     // if
     $completed_tasks = $this->active_task_parent->getCompletedTasks();
     $this->smarty->assign(array('completed_tasks' => $completed_tasks));
 }