function window_open_blank(url,sirka,vyska,scroll) {
    wasOpen = false;
    win = window.open(url, '', 'toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars='+scroll+',resizable=yes,copyhistory=no,width='+sirka+',height='+vyska+',top=10,left=50');
    if(typeof(win)=='object') {
        return true;
    } else {
        return false;
    }
}