codice:
<script language="JavaScript1.2">
var IE = document.all?true:false
var tempX = 0
var tempY = 0
	if (!IE) document.captureEvents(Event.MOUSEMOVE)
	document.onmousemove = getMouseXY;

function getMouseXY(e) {
  if (IE) {
    tempX = event.clientX + (window.opera?0:document.body.scrollLeft)
    tempY = event.clientY + (window.opera?0:document.body.scrollTop)
  } else {
    tempX = e.pageX
    tempY = e.pageY
  }  
  if (tempX < 0){tempX = 0}
  if (tempY < 0){tempY = 0}  
  return true
}


function copri(cosa) {
	document.getElementById(cosa).style.visibility='hidden';
}

function vedi(cosa) {
	document.getElementById(cosa).style.visibility='visible';
	document.getElementById(cosa).style.top=''+tempY+'px';
	document.getElementById(cosa).style.left=''+tempX+'px';
}
</script>
ciao