browserName = navigator.appName;
browserVer = parseInt(navigator.appVersion);
var wersja="0"
if (browserName == "Netscape" && browserVer >= 3  || browserName == "Microsoft Internet Explorer" && browserVer >= 4) wersja = "tak";
  if (wersja == "tak")
  {
    menu1on = new Image(19,13);
    menu1on.src = "images/gb_on.gif";
    menu1off = new Image(19,13);
    menu1off.src = "images/gb_off.gif";
  }

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

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