rem: mailWindowService.openMessengerWindowWithUri(uriToOpen, keyToSelect); 
add: mailWindowService.openMessengerWindowWithUri("mail:3pane", uriToOpen, keyToSelect); 
context: function MsgOpenNewWindowForFolder(uri, key){  var uriToOpen = uri;  var keyToSelect = key;  if (!uriToOpen)    // use GetSelectedFolderURI() to find out which message to open instead of    // GetLoadedMsgFolder().QueryIntervace(Components.interfaces.nsIRDFResource).value.    // This is required because on a right-click, the currentIndex value will be    // different from the actual row that is highlighted.  GetSelectedFolderURI()    // will return the message that is highlighted.    uriToOpen = GetSelectedFolderURI();  if (uriToOpen) {   // get the messenger window open service and ask it to open a new window for us   var mailWindowService = Components.classes["@mozilla.org/messenger/windowservice;1"].getService(Components.interfaces.nsIMessengerWindowService);   if (mailWindowService)     mailWindowService.openMessengerWindowWithUri(uriToOpen, keyToSelect);  }}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/1fc6f3670b8c6508b912cf3009c330d3db918b58/mailWindowOverlay.js/buggy/mailnews/base/resources/content/mailWindowOverlay.js