Muispositie werkt niet in FF

function doSomething(e) {
	var posx = 0;
	var posy = 0;
	if (!e) var e = window.event;
	if (e.pageX || e.pageY) 	{
		posx = e.pageX;
		posy = e.pageY;
	}
	else if (e.clientX || e.clientY) 	{
		posx = e.clientX + document.body.scrollLeft
			+ document.documentElement.scrollLeft;
		posy = e.clientY + document.body.scrollTop
			+ document.documentElement.scrollTop;
	}
document.getElementById('div').style.top = posY + 'px';
document.getElementById('div').style.left = posX + 'px';
}

function doSomething(e) {
	var posx = 0;
	var posy = 0;
	if (!e) var e = window.event;
	if (e.pageX || e.pageY) 	{
		posx = e.pageX;
		posy = e.pageY;
	}
	else if (e.clientX || e.clientY) 	{
		posx = e.clientX + document.body.scrollLeft
			+ document.documentElement.scrollLeft;
		posy = e.clientY + document.body.scrollTop
			+ document.documentElement.scrollTop;
	}
document.getElementById('div').style.top = posY + 'px';
document.getElementById('div').style.left = posX + 'px';
}

var isIE = document.all;
var mouseX = 0;
var mouseY = 0;

function getMouseXY(e)
{ 
  if (!e) e = window.event;
  if (e)
  { 
  	mouseX = isIE ? (e.clientX + document.body.scrollLeft) : e.pageX;
  	mouseY = isIE ? (e.clientY + document.body.scrollTop) : e.pageY;
  }
}

document.getElementById('div').style.top = mouseY + 'px';
document.getElementById('div').style.left = mouseX + 'px';

var isIE = document.all;
var mouseX = 0;
var mouseY = 0;
 
function getMouseXY(e)
{ 
  if (!e) e = window.event;
  if (e)
  { 
  	mouseX = isIE ? (e.clientX + document.body.scrollLeft) : e.pageX;
  	mouseY = isIE ? (e.clientY + document.body.scrollTop) : e.pageY;
  }
}
 
document.getElementById('div').style.top = mouseY + 'px';
document.getElementById('div').style.left = mouseX + 'px';