var xPos = 20;
var yPos = 10;
jsimg.style.left= xPos;
jsimg.style.top = yPos;
var step = 1;
var delay = 30; 
var width,height,Hoffset,Woffset;
var y = 1;
var x = 1;
var interval;
jsimg.visibility = "visible";
function changePos() 
{
    var _pagePos=getPagePosition( window );
    width = _pagePos.clientWidth;
    height = _pagePos.clientHeight;
    Hoffset = jsimg.offsetHeight;
    Woffset = jsimg.offsetWidth;
    if (y) 
    {
        yPos = yPos + step;
    }
    else 
    {
        yPos = yPos - step;
    }
    if (yPos < 0) 
    {
        y = 1;
        yPos = 0;
    }
    if (yPos >= (height - Hoffset)) 
    {
        y = 0;
        yPos = (height - Hoffset);
    }
    if (x) 
    {
        xPos = xPos + step;
    }
    else 
    {
        xPos = xPos - step;
    }
    if (xPos < 0) 
    {
        x = 1;
        xPos = 0;
    }
    if (xPos >= (width - Woffset)) 
    {
        x = 0;
        xPos = (width - Woffset);
    }
    
    jsimg.style.left = xPos + _pagePos.scrollLeft+"px";
    jsimg.style.top = yPos + _pagePos.scrollTop+"px";
}
function start() 
{
    interval = setInterval('changePos();', delay);
}
function pause_resume() 
{
    clearInterval(interval);
}
function hides()  
{
    jsimg.style.visibility="hidden";
}
start();