function lightup(imageobject, opacity){
 if (navigator.appName.indexOf("Netscape")!=-1
  &&parseInt(navigator.appVersion)>=5)
    imageobject.style.MozOpacity=opacity/100
 else if (navigator.appName.indexOf("Microsoft")!= -1 
  &&parseInt(navigator.appVersion)>=4)
    imageobject.filters.alpha.opacity=opacity
}