/***********************************************
* Cool DHTML tooltip script- © Dynamic Drive DHTML code library (www.dynamicdrive.com)
* This notice MUST stay intact for legal use
* Visit Dynamic Drive at http://www.dynamicdrive.com/ for full source code
***********************************************/

var offsetxpoint=-60 //Customize x offset of tooltip
var offsetypoint=-35 //Customize y offset of tooltip
var ie=document.all
var ns6=document.getElementById && !document.all
var enabletip=false
if (ie||ns6)
{
  var tipobj=document.all ? document.all["dhtmltooltip"] : document.getElementById ? document.getElementById("dhtmltooltip") : document.layers ? document.layers["dhtmltooltip"] : ""
}
function ietruebody(){
return (document.compatMode && document.compatMode!="BackCompat")? document.documentElement : document.body
}

function ddrivetip(thetext, thecolor, thewidth)
{
   var tipobj=document.all ? document.all["dhtmltooltip"] : document.getElementById ? document.getElementById("dhtmltooltip") : document.layers ? document.layers["dhtmltooltip"] : ""

   if (ns6||ie)
   {
      if (typeof thewidth!="undefined") tipobj.style.width=thewidth+"px"
      if (typeof thecolor!="undefined" && thecolor!="") tipobj.style.backgroundColor=thecolor
      tipobj.innerHTML=thetext
      enabletip=true
      return false
   }
}

function positiontip(e)
{
   if (enabletip)
   {
      var curX=(ns6)?e.pageX : event.x+ietruebody().scrollLeft;
      var curY=(ns6)?e.pageY : event.y+ietruebody().scrollTop;
      //Find out how close the mouse is to the corner of the window
      var rightedge=ie&&!window.opera? ietruebody().clientWidth-event.clientX-offsetxpoint : window.innerWidth-e.clientX-offsetxpoint-20
      var bottomedge=ie&&!window.opera? ietruebody().clientHeight-event.clientY-offsetypoint : window.innerHeight-e.clientY-offsetypoint-20

      var leftedge=(offsetxpoint<0)? offsetxpoint*(-1) : -1000

      //if the horizontal distance isn't enough to accomodate the width of the context menu
      if (rightedge<tipobj.offsetWidth)
      //move the horizontal position of the menu to the left by it's width
         tipobj.style.left=ie? ietruebody().scrollLeft+event.clientX-tipobj.offsetWidth+"px" : window.pageXOffset+e.clientX-tipobj.offsetWidth+"px"
      else if (curX<leftedge)
         tipobj.style.left="5px"
      else
         //position the horizontal position of the menu where the mouse is positioned
         tipobj.style.left=curX+offsetxpoint+"px"

      //same concept with the vertical position
      if (bottomedge<tipobj.offsetHeight)
            tipobj.style.top=ie? ietruebody().scrollTop+event.clientY-tipobj.offsetHeight-offsetypoint+"px" : window.pageYOffset+e.clientY-tipobj.offsetHeight-offsetypoint+"px"
      else
            tipobj.style.top=curY+offsetypoint+"px"
      tipobj.style.visibility="visible"
   }
}

function hideddrivetip()
{
   if (ns6||ie)
   {
      enabletip=false
      tipobj.style.visibility="hidden"
      tipobj.style.left="-1000px"
      tipobj.style.backgroundColor=''
      tipobj.style.width=''
   }
}

document.onmousemove=positiontip
<!--tooltip end-->