function na_change_img_src(name, nsdoc, rpath, preload)
{ 
  var img = eval((navigator.appName.indexOf('Netscape', 0) != -1) ? nsdoc+'.'+name : 'document.all.'+name);
  if (name == '')
    return;
  if (img) {
    img.altsrc = img.src;
    img.src    = rpath;
  } 
}

function na_restore_img_src(name, nsdoc)
{
  var img = eval((navigator.appName.indexOf('Netscape', 0) != -1) ? nsdoc+'.'+name : 'document.all.'+name);
  if (name == '')
    return;
  if (img && img.altsrc) {
    img.src    = img.altsrc;
    img.altsrc = null;
  } 
}