var pixel = 1;
var scrolled_pixel = 0;
var max_height = 0;
var displayed_height = 120;

function init() {
   if(document.getElementById) {
      max_height = document.getElementById("ticker").offsetHeight + displayed_height;
      show_ticker();
   }
}

function show_ticker() {
  if(document.getElementById)
   document.getElementById("ticker").style.top = (displayed_height - scrolled_pixel) + "px";
  scrolled_pixel += pixel;
  if(scrolled_pixel > max_height)
   scrolled_pixel = 0;
  window.setTimeout("show_ticker()",50);
}