function hookEvent(element, eventName, callback)
{
  if(typeof(element) == "string")
    element = document.getElementById(element);
  if(element == null)
    return;
  if(element.addEventListener)
  {
    if(eventName == 'mousewheel')
      element.addEventListener('DOMMouseScroll', callback, false);  
    element.addEventListener(eventName, callback, false);
  }
  else if(element.attachEvent)
    element.attachEvent("on" + eventName, callback);
}

function cancelEvent(e)
{
  e = e ? e : window.event;
  if(e.stopPropagation)
    e.stopPropagation();
  if(e.preventDefault)
    e.preventDefault();
  e.cancelBubble = true;
  e.cancel = true;
  e.returnValue = false;
  return false;
}

function leftDiv(e)
{
  e = e ? e : window.event;
  var normal = e.detail ? e.detail * -1 : e.wheelDelta / 40;
  div = document.getElementById('content_left');
  y = div.scrollTop;
  if (normal > 0)
  {
  	y-=15;
  }
  else if (normal < 0)
  {
	y+=15;
  }
  div.scrollTop=y;

  return cancelEvent(e);  
}

function middleDiv(e)
{
  e = e ? e : window.event;
  var normal = e.detail ? e.detail * -1 : e.wheelDelta / 40;
  div = document.getElementById('content_middle');
  y = div.scrollTop;
  if (normal > 0)
  {
  	y-=15;
  }
  else if (normal < 0)
  {
	y+=15;
  }
  div.scrollTop=y;

  return cancelEvent(e);  
}

function rightDiv(e)
{
  e = e ? e : window.event;
  var normal = e.detail ? e.detail * -1 : e.wheelDelta / 40;
  div = document.getElementById('content_right');
  y = div.scrollTop;
  if (normal > 0)
  {
  	y-=15;
  }
  else if (normal < 0)
  {
	y+=15;
  }
  div.scrollTop=y;

  return cancelEvent(e);  
}

hookEvent('content_left', 'mousewheel', leftDiv);
hookEvent('content_middle', 'mousewheel', middleDiv);
hookEvent('content_right', 'mousewheel', rightDiv);