rem: ss.undoCloseTab(window, aIndex); 
add: ss.undoCloseTab(window, aIndex || 0); 
context: function undoCloseTab(aIndex) {  var ss = Cc["@mozilla.org/browser/sessionstore;1"].           getService(Ci.nsISessionStore);  ss.undoCloseTab(window, aIndex);}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/1be77a73464f203f8c629a4819341f7a3fffbc03/browser.js/buggy/browser/base/content/browser.js