browserName = navigator.appName;
browserVer = parseInt ( navigator.appVersion );
version = "n2";
if ( browserName == "Netscape" && browserVer >= 3 ) version = "n3";
if ( browserName == "Microsoft Internet Explorer" && browserVer >=4 ) version = "e4";

if ( version == "n3" || version == "e4" )
{        light_on = new Image ( 25, 25 );
        light_on.src = "images/butthon.gif";
        light_off = new Image ( 25, 25 );
        light_off.src = "images/butt.gif";}

function button_on ( imgName )
{
        if ( version == "n3" || version == "e4" )
 {                document [imgName].src = light_on.src;  }
}
function button_off ( imgName )
{        if ( version == "n3" || version == "e4" )
        {                document [imgName].src = light_off.src;        }}// --></script>