var t1, t2;
  
  function move_top() {
   	document.getElementById('scroll_clipper').scrollTop = document.getElementById('scroll_clipper').scrollTop+10;
	if(document.getElementById('scroll_clipper').scrollTop != 0)
	{
		t1 = setTimeout('move_top()',100);
	}
	else
	{
		stop(t1);
	}
  }
  
  function move_bottom() {
   	document.getElementById('scroll_clipper').scrollTop = document.getElementById('scroll_clipper').scrollTop-10;
	if(document.getElementById('scroll_clipper').scrollTop != 0)
	{
		t2 = setTimeout('move_bottom()',100);
	}
	else
	{
		stop(t2);
	}
  }
  
  function stop(zaman)
  {
	clearTimeout(zaman);
  }