var offsetfromcursorX = 12;
var offsetfromcursorY = 10;
var offsetdivfrompointerX = 10;
var offsetdivfrompointerY = 13;
document.write('<div id="dhtmltooltip"></div>');
document.write('<img id="dhtmlpointer" src="http://www.c3zone.net/users/2611/10/63/87/album/pointe10.gif">');
var ie = document.all;
var ns6 = document.getElementById && ! document.all;
var enabletip = false;
var  tipobj = document.getElementById("dhtmltooltip");
var pointerobj = document.getElementById("dhtmlpointer");
function ietruebody() {
  return (document.compatMode && document.compatMode != "BackCompat") ? document.documentElement : document.body;
}
String.prototype.trim = function () {
    return this.replace(/^\s*/, "").replace(/\s*$/, "");
}
function showtip(thetext, thewidth, thecolor) {
  if (ns6 || ie) {
      if (typeof thewidth != "undefined")
        tipobj.style.width = thewidth + "px";
      if (typeof thecolor != "undefined" && thecolor != "")
        tipobj.style.backgroundColor = thecolor;
      thetext = thetext.trim();
      var arr = thetext.split(" ");
      for(i=0;i<arr.length;i++)
        if(arr[i].length>=40)
            thetext=thetext.replace(arr[i],arr[i].substr(0,40)+"...");
      tipobj.innerHTML = thetext;     
      enabletip = true;
      return false;
  }
}
function positiontip(e) {
  if (enabletip) {     
      var nondefaultpos = false;
      var curX = (ns6) ? e.pageX : event.clientX + ietruebody().scrollLeft;
      var curY = (ns6) ? e.pageY : event.clientY + ietruebody().scrollTop;
      var winwidth = ie && ! window.opera ? ietruebody().clientWidth : window.innerWidth - 20;
      var winheight = ie && ! window.opera ? ietruebody().clientHeight : window.innerHeight - 20;
      var rightedge = ie && ! window.opera ? winwidth - event.clientX - offsetfromcursorX : winwidth - e.clientX - offsetfromcursorX;
      var bottomedge = ie && ! window.opera ? winheight - event.clientY - offsetfromcursorY : winheight - e.clientY - offsetfromcursorY;
      var leftedge = (offsetfromcursorX < 0) ? offsetfromcursorX * (- 1) : - 1000;
      if (rightedge < tipobj.offsetWidth) {
        tipobj.style.left = curX - tipobj.offsetWidth + "px";
        nondefaultpos = true;
      }
      else if (curX < leftedge)
        tipobj.style.left = "5px";
      else {
        tipobj.style.left = curX + offsetfromcursorX - offsetdivfrompointerX + "px";
        pointerobj.style.left = curX + offsetfromcursorX + "px";
      }
      if (bottomedge < tipobj.offsetHeight) {
        tipobj.style.top = curY - tipobj.offsetHeight - offsetfromcursorY + "px";
        nondefaultpos = true;
      }
      else {
        tipobj.style.top = curY + offsetfromcursorY + offsetdivfrompointerY + "px";
        pointerobj.style.top = curY + offsetfromcursorY + "px";
      }
      tipobj.style.visibility = "visible";
 
      if (! nondefaultpos)
        pointerobj.style.visibility = "visible";
      else
        pointerobj.style.visibility = "hidden";
  }
}
function hidetip() {
  if (ns6 || ie) {
      enabletip = false;
      tipobj.style.visibility = "hidden";
      pointerobj.style.visibility = "hidden";
      tipobj.style.left = "-1000px";
      tipobj.style.backgroundColor = '';
      tipobj.style.width = '';
  }
}
document.onmousemove = positiontip;

<script type="text/javascript" src="url trang html"></script>

</head>

/* tooltip-------------------------------------------------------------*/

#dhtmlpointer, #dhtmltooltip
{
  z-index: 999;
  left: -300px; top:0px;
  visibility: hidden;
  position: absolute;
}
#dhtmltooltip
{-moz-opacity:.8;filter:alpha(opacity=80);left:-300px;opacity:.8;position:absolute;top:0;visibility:hidden;z-index:999}#c3tooltip{-moz-border-radius:6px;-webkit-border-radius:6px;background-color:#000;border:#000 0 solid;border-radius:6px;color:#fff;font-family:Arial;font-size:9pt;font-weight:700;max-width:340px;padding:15px;text-align:left;width:expression(document.body.clientWidth>340?"340px":"auto")}