var timer;

    function blockoff() {
      block = document.getElementById("block")
      block.style.display = 'none';
    }


    function delayedblockoff() {
      timer = window.setTimeout("blockoff()",1000);
    }

    function blockon() {
      if (timer) {
          window.clearTimeout(timer);
          timer=null;
      }
      block.style.display = 'block';
    }