rem: mailSession.AddFolderListener(folderListener); 
add: var nsIFolderListener = Components.interfaces.nsIFolderListener; var notifyFlags = nsIFolderListener.intPropertyChanged | nsIFolderListener.event; mailSession.AddFolderListener(folderListener, notifyFlags); 
context: function AddToSession(){    try {        var mailSession = Components.classes[mailSessionContractID].getService(Components.interfaces.nsIMsgMailSession);                mailSession.AddFolderListener(folderListener);	} catch (ex) {        dump("Error adding to session\n");    }}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/ef119303bf00574b1effa319669407ac5054fb59/msgMail3PaneWindow.js/clean/mailnews/base/resources/content/msgMail3PaneWindow.js