function check_print_preview() {
    return location.href.match(/[?&]Print$/);
}

function print_click() {
    if (check_print_preview()) {
        window.print();
    } else {
        var url = location.href.replace(/#.*/, "");
        if (url.indexOf("?") != -1)
            url += "&Print";
        else
            url += "?Print";
        window.open(url, "printpreview", "width=700,height=500,resizable=1,toolbar=1,menubar=1,scrollbars=1,status=0");
    }
    
    return false;
}

function do_print_preview(print_css_url) {
    if (check_print_preview()) {
        var link = document.createElement("link");
        link.rel = "stylesheet";
        link.type = "text/css";
        link.href = print_css_url;
        document.getElementsByTagName("head")[0].appendChild(link);
    }
}