var scrolltimer = 0;
function scroll(n) {
  var tf = document.getElementById("textframe");
  var cf = document.getElementById("contentframe");
  var top = parseInt(tf.style.top);
  var top2 = top + n;
  var diff = tf.offsetHeight - cf.offsetHeight;

  if(top2 > 0) top2 = 0;
  if(top2 < -diff) top2 = -diff;
  tf.style.top = top2 + "px";
  if(scrolltimer) clearTimeout(scrolltimer);
  scrolltimer = setTimeout("scroll(" + n + ")", 20);
}

function stopscroll() {
  if(scrolltimer) clearTimeout(scrolltimer);
  scrolltimer = 0;
}