function openPopoupWindow(url,w,h){
    if(!w)w=800;
    if(!h)h=600;
    
    var l=Math.floor((screen.width-w)/2);
    var t=Math.floor((screen.height-h)/2);
    
    window.open(url,"","width=" + w + ",height=" + h + ",top=" + t + ",left=" + l);
    
    return false;
}