function scroll(div_id, div_height, space_top, space_bottom){
    if(typeof window.pageYOffset != 'undefined') { 
        if(window.pageYOffset < space_top) {
            document.getElementById(div_id).style.top = space_top+"px";
        } else if(window.pageYOffset < document.body.scrollHeight - div_height - space_bottom) {
            document.getElementById(div_id).style.top = window.pageYOffset+"px";
        } else {
            pos = document.body.scrollHeight - div_height - space_bottom;
            pos = pos+"px";
            document.getElementById(div_id).style.top =  pos;
        }
    } else { 
        if(document.documentElement.scrollTop <= space_top) {
            document.getElementById(div_id).style.top =  space_top;
        } else {
            document.getElementById(div_id).style.top =  document.documentElement.scrollTop;
        }
        
        if(document.documentElement.scrollTop >= document.body.scrollHeight - div_height - space_bottom) {
            document.getElementById(div_id).style.top =  document.body.scrollHeight - div_height - space_bottom;
        }
    } 
    
setTimeout("scroll(\""+div_id+"\",\""+div_height+"\",\""+space_top+"\",\""+space_bottom+"\")", 200);

}