function isNav()
{
  // Note: Opera and WebTV spoof Navigator...strict client detection. 
  // If you want to allow spoofing, take out the tests for opera and webtv. 
  var agt=navigator.userAgent.toLowerCase();       
	return  ((agt.indexOf('mozilla')!=-1) && (agt.indexOf('spoofer')==-1) 
            && (agt.indexOf('compatible') == -1) && (agt.indexOf('opera')==-1) 
            && (agt.indexOf('webtv')==-1)); 
}

function setButtonText(button, text)
{
  if (button) { 
    if (button.childNodes[0]) { 
      button.childNodes[0].nodeValue = text; 
    } else if (button.value) { 
      button.value = text; 
    } else { //if (button.innerHTML) 
      button.innerHTML = text; 
    } 
  }
}

function hideElementByID(id) 
{
  var element = document.getElementById(id);
  if (element != null)
    element.style.display = "none";
}