/**
  * Marks the selected thread.
  */
 public function mark()
 {
     if ($this->thread != null) {
         $this->thread->mark();
     } else {
         if (is_array($this->threadID)) {
             foreach ($this->threadID as $threadID) {
                 $thread = new ThreadEditor($threadID);
                 $thread->enter();
                 $thread->mark();
             }
         }
     }
 }