var browserName = navigator.appName;
var browserVer = parseInt(navigator.appVersion);

if (browserName == "Netscape" && browserVer >= 3) version = "ok"
else if (browserName == "Microsoft Internet Explorer" && browserVer >=4) version="ok" 
else version = "";

if (version == "ok")
                {

                alt1on=new Image(140,15); alt1on.src="library/omlek2.gif";
                alt2on=new Image(140,15); alt2on.src="library/loksam2.gif";
                alt3on=new Image(140,15); alt3on.src="library/bibl2.gif";
                alt4on=new Image(140,15); alt4on.src="library/mail2.gif";
                alt5on=new Image(140,15); alt5on.src="library/hside2.gif";
                                            
                alt1off=new Image(140,15); alt1off.src="library/omlek1.gif";
                alt2off=new Image(140,15); alt2off.src="library/loksam1.gif";
                alt3off=new Image(140,15); alt3off.src="library/bibl1.gif";
                alt4off=new Image(140,15); alt4off.src="library/mail1.gif";
                alt5off=new Image(140,15); alt5off.src="library/hside1.gif";
                }

function img_act(imgName)
                {
                if (version == "ok")
                                {
                                imgOn = eval(imgName + "on.src");
                                document [imgName].src = imgOn;
                                }
                }

function img_inact(imgName)
                {
                if (version == "ok")
                                {
                                imgOff = eval(imgName + "off.src");
                                document [imgName].src = imgOff;
                                }
                }