var xPos = 300;
var yPos = 200;
var step = 1;
var delay = 30;
var height = 0;
var Hoffset = 0;
var Woffset = 0;
var yon = 0;
var xon = 0;
var pause = true;
var interval;
var float_ad; 

function changePos() {
	//width = document.documentElement.clientWidth;
	//height = document.documentElement.clientHeight;
	width = document.body.clientWidth;
	height = document.body.clientHeight;
	if(height < document.documentElement.clientHeight){
		height = document.documentElement.clientHeight;	
	}
	Hoffset = float_ad.offsetHeight;
	Woffset = float_ad.offsetWidth;
	float_ad.style.left = xPos + document.body.scrollLeft + "px";
	float_ad.style.top = yPos + document.body.scrollTop + "px";
	if (yon)
	{ yPos = yPos + step; }
	else
	{ yPos = yPos - step; }
	if (yPos < 0)
	{ yon = 1; yPos = 0; }
	if (yPos >= (height - Hoffset))
	{ yon = 0; yPos = (height - Hoffset); }
	if (xon)
	{ xPos = xPos + step; }
	else
	{ xPos = xPos - step; }
	if (xPos < 0)
	{ xon = 1; xPos = 0; }
	if (xPos >= (width - Woffset))
	{ xon = 0; xPos = (width - Woffset); }	
}


function pause_resume() {
	if (pause) {
		clearInterval(interval);
		pause = false;
	}
	else {
		interval = setInterval('changePos()', delay);
		pause = true;
	}
}
function start(){
	float_ad = document.getElementById("float_ad");
	float_ad.style.top = yPos + "px";
	float_ad.visibility = "visible";
	interval = setInterval('changePos()', delay);
}
start();