var direction = 1;
  var scrollstep = 1;
  var scrolldelay = 40;
  var scrollstop;  
  var isScrolling;

  function stopScroll() {
      scrollstop = true;
      window.clearTimeout(isScrolling);
  }


  function scrollContinue(obj) {
      
      window.clearTimeout(isScrolling);
      
      if(!scrollstop) {
          var elmt = document.getElementById(obj);
          var y = parseInt(elmt.style.top);
          if(y <= (-1 * elmt.offsetHeight)/2) {
                elmt.style.top = "0px";
          }
          else {
              y -= scrollstep;
              elmt.style.top = y + 'px';
          }
          isScrolling = window.setTimeout("scrollContinue('"+obj+"')", scrolldelay);
      }
  }

  function startScroll(obj) {

      scrollstop = false;
      scrollContinue(obj);
  }

  function setTopValue(obj,val) {
      
      if(document.getElementById) {
         document.getElementById(obj).style.top = val + 'px';
      }
  }