var floatImg = document.getElementById("oImg");
 floatImg.style.display = 'block';
 floatImg.style.zIndex = 1000;
    var delay = 10;
    var speed = 1;
    var flagX = 0;
    var flagY = 0;
    function flowImg() {
        var bWidth = document.body.clientWidth;
        var bHeight = document.body.clientHeight;
        var bLeft = document.body.scrollLeft;
        var bTop = document.body.scrollTop;
        
        var iWidth = floatImg.offsetWidth;
        var iHeight = floatImg.offsetHeight;
        var iLeft = parseInt(floatImg.style.left)||0;
        var iTop = parseInt(floatImg.style.top)||0;
        
        if(iLeft < (bWidth - iWidth) && flagX == 0) {
            floatImg.style.left = (iLeft + speed) + "px";
        }
        else if(iLeft >= (bWidth - iWidth) && flagX ==0) {
            flagX = 1;
        }
        else if(iLeft > 0 && flagX == 1) {
            floatImg.style.left = (iLeft - speed) + "px";
        }
        else if(0 >= iLeft && flagX == 1) {
            flagX = 0;
        }
        if(iTop < (bHeight - iHeight) && flagY == 0) {
            floatImg.style.top = (iTop + speed) + "px";
        }
        else if(iTop >= (bHeight - iHeight) && flagY ==0) {
            flagY = 1;
        }
        else if(iTop > 0 && flagY == 1) {
            floatImg.style.top = (iTop - speed) + "px";
        }
        else if(0 >= iTop && flagY == 1) {
            flagY = 0;
        }
    }
    
    var imgInterval = setInterval("flowImg()", delay);
    floatImg.onmouseover = function() {clearInterval(imgInterval);}
    floatImg.onmouseout = function() {imgInterval = setInterval("flowImg()", delay);}