function on(element) {
	if (element!=null) element.src = 'images/' + element.id + '-on.png';
}

function off(element) {
	if (element!=null) element.src = 'images/' + element.id + '-off.png';
}

function showHide(id) {
   if(document.getElementById) {
      element = document.getElementById(id);
   } else if(document.all) {
      element = document.all[id];
   } else return;

   if(element.style) {
      if(element.style.display == 'block' ){
         element.style.display = 'none';
      } else {
         element.style.display = 'block';
      }
   }
}