rem: gExtensionManager.removeDownloadObserverAt(gObserverIndex); 
add: gExtensionManager.removeDownloadListenerAt(gObserverIndex); 
context: function Shutdown() {  if (gWindowState != "extensions")    gExtensionsView.removeEventListener("richview-select", onThemeSelect, false);    gExtensionManager.removeDownloadObserverAt(gObserverIndex);  var os = Components.classes["@mozilla.org/observer-service;1"]                     .getService(Components.interfaces.nsIObserverService);  if (gDownloadManager)     os.removeObserver(gDownloadManager, "xpinstall-download-started");}
meta: 5872	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5872/9d35a22086947d43c8fc85debb6f35b5f0f3d14d/extensions.js/buggy/toolkit/mozapps/extensions/content/extensions.js