rem: if (feedListbox.getRowCount() > 0) document.getElementById("feedTab").hidden = false; 
add: document.getElementById("feedTab").hidden = feedListbox.getRowCount() == 0; 
context: function initFeedTab(){  const feedTypes = {    "application/rss+xml": gBundle.getString("feedRss"),    "application/atom+xml": gBundle.getString("feedAtom"),    "text/xml": gBundle.getString("feedXML"),    "application/xml": gBundle.getString("feedXML"),    "application/rdf+xml": gBundle.getString("feedXML")  };  // get the feeds  var linkNodes = gDocument.getElementsByTagName("link");  var length = linkNodes.length;  for (var i = 0; i < length; i++) {    var feed = recognizeFeedFromLink(linkNodes[i], gDocument.nodePrincipal);    if (feed) {      var type = feed.type;      if (type in feedTypes)        type = feedTypes[type];      else        type = feedTypes["application/rss+xml"];      addRow(feed.title, type, feed.href);    }  }  var feedListbox = document.getElementById("feedListbox");  if (feedListbox.getRowCount() > 0)    document.getElementById("feedTab").hidden = false;}
meta: 10520	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/10520/2799ebb797f15a2295f5a859b14f2dc70cc49134/feeds.js/buggy/browser/base/content/pageinfo/feeds.js