function addSearch() {
    if (/Firefox[\/\s](\d+\.\d+)/.test(navigator.userAgent)) {
        document.body.background="images/firefox.png";
    } else if (/MSIE (\d+\.\d+);/.test(navigator.userAgent) && Number(RegExp.$1)>=7) {
        document.body.background="images/ie.png";
    } else {
        showText("pluginerror");
    }
}

function showText(text) {
    document.getElementById('pluginerror').style.display="none";
    document.getElementById('explanation').style.display="none";
    document.getElementById('changelog').style.display="none";
    
    document.getElementById(text).style.display="block";
}