public function DismissAnnouncement($DiscussionID = '') {
      // Confirm announcements may be dismissed
      if (!C('Vanilla.Discussions.Dismiss', 1)) {
         throw PermissionException('Vanilla.Discussions.Dismiss');
      }
      
      // Make sure we are posting back.
      if (!$this->Request->IsPostBack())
         throw PermissionException('Javascript');
      
      $Session = Gdn::Session();
      if (
         is_numeric($DiscussionID)
         && $DiscussionID > 0
         && $Session->UserID > 0
      ) $this->DiscussionModel->DismissAnnouncement($DiscussionID, $Session->UserID);

      // Redirect back where the user came from if necessary
      if ($this->_DeliveryType === DELIVERY_TYPE_ALL)
         Redirect('discussions');
      
      $this->JsonTarget("#Discussion_$DiscussionID", NULL, 'SlideUp');
      
      $this->Render('Blank', 'Utility', 'Dashboard');
   }