browserName = navigator.appName;   // detect browser 
        browserVer = parseInt(navigator.appVersion);
             if (browserName == "Netscape" && browserVer >= 3) browserVer = "1";
        else if (browserName == "Microsoft Internet Explorer" && browserVer == 4) browserVer = "1";
             else browserVer = "2";

//preload images:
if (browserVer == 1) {
        btn1 = new Image;
        btn1.src = "graphics/pointer_blank.gif";      
        btn2 = new Image;
        btn2.src = "graphics/pointer.gif";
}

function img_act(imgDocID, imgObjName) {
if (browserVer == 1) {
        document.images[imgDocID].src = eval(imgObjName + ".src");
}}