function popUp(url, myHeight, myWidth, scrollbar)
{
        newwindow=window.open(url,'name','top='+Math.floor(screen.height/2-myHeight/2)+',left='+Math.floor(screen.width/2-myWidth/2)+',height='+myHeight+',width='+myWidth+',scrollbars=yes');
        if (window.focus) {newwindow.focus()}
        return false;
}