/**
  * Copies the marked threads.
  */
 public function copy()
 {
     if ($this->board == null) {
         throw new IllegalLinkException();
     }
     $this->board->checkModeratorPermission('canCopyThread');
     ThreadEditor::copyAll($this->threadIDs, $this->boardID);
     ThreadEditor::unmarkAll();
     // set last post
     $this->board->refresh();
     $this->board->setLastPosts();
     self::resetCache();
     HeaderUtil::redirect($this->url);
     exit;
 }