rem: pref.QueryInterface(Components.interfaces.nsIPrefBranchInternal); 
add: pref.QueryInterface(Components.interfaces.nsIPrefBranch2); 
context: function OnUnloadMessenger(){  OnLeavingFolder(gMsgFolderSelected);  // mark all read in current folder  accountManager.removeIncomingServerListener(gThreePaneIncomingServerListener);  pref.QueryInterface(Components.interfaces.nsIPrefBranchInternal);  pref.removeObserver("mail.pane_config.dynamic", MailPrefObserver);  pref.removeObserver("mail.showFolderPaneColumns", MailPrefObserver);  // FIX ME - later we will be able to use onload from the overlay  OnUnloadMsgHeaderPane();  OnMailWindowUnload();}
meta: 5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5459/361daac9367ad464688c4da3c3206d18cb2ae94e/msgMail3PaneWindow.js/clean/mail/base/content/msgMail3PaneWindow.js