Thầy Cô copy đoạn code sau và dán vào khối chính bất kỳ là xong 

 <script type="text/javascript">

var trailimage=["http://d.violet.vn/uploads/resources/634/VietNam.gif", 100, 60] //image path, plus width and height

var offsetfrommouse=[-5,10] //image x,y offsets from cursor position in pixels. Enter 0,0 for no offset

var displayduration=0 //duration in seconds image should remain visible. 0 for always.

if (document.getElementById || document.all)

document.write('<div id="trailimageid" style="position:absolute;visibility:visible;left:0px;top:0px;width:1px;height:1px"><img src="'+trailimage[0]+'" border="0" width="'+trailimage[1]+'px" height="'+trailimage[2]+'px"><\/div>')

function gettrailobj(){

if (document.getElementById)

return document.getElementById("trailimageid").style

else if (document.all)

return document.all.trailimagid.style

}

function truebody(){

return (!window.opera && document.compatMode && document.compatMode!="BackCompat")? document.documentElement : document.body

}

function hidetrail(){

gettrailobj().visibility="hidden"

document.onmousemove=""

}

function followmouse(e){

var xcoord=offsetfrommouse[0]

var ycoord=offsetfrommouse[1]

if (typeof e != "undefined"){

xcoord+=e.pageX

ycoord+=e.pageY

}

else if (typeof window.event !="undefined"){

xcoord+=truebody().scrollLeft+event.clientX

ycoord+=truebody().scrollTop+event.clientY

}

var docwidth=document.all? truebody().scrollLeft+truebody().clientWidth : pageXOffset+window.innerWidth-15

var docheight=document.all? Math.max(truebody().scrollHeight, truebody().clientHeight) : Math.max(document.body.offsetHeight, window.innerHeight)

if (xcoord+trailimage[1]+3>docwidth || ycoord+trailimage[2]> docheight)

gettrailobj().display="none"

else

gettrailobj().display=""

gettrailobj().left=xcoord+"px"

gettrailobj().top=ycoord+"px"

}

document.onmousemove=followmouse

if (displayduration>0)

setTimeout("hidetrail()", displayduration*1000)

</script>

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