add: if (row.value == -1) return; 
context: function FolderPaneOnClick(event){    // we only care about button 0 (left click) events    if (event.button != 0)        return;    var folderOutliner = GetFolderOutliner();    var row = {};    var col = {};    var elt = {};    folderOutliner.outlinerBoxObject.getCellAt(event.clientX, event.clientY, row, col, elt);    if (elt.value == "twisty")    {        var folderResource = GetFolderResource(folderOutliner, row.value);        var msgFolder = folderResource.QueryInterface(Components.interfaces.nsIMsgFolder);        if (!(folderOutliner.outlinerBoxObject.view.isContainerOpen(row.value)))        {            var isServer = GetFolderAttribute(folderOutliner, folderResource, "IsServer");            if (isServer == "true")            {                var server = msgFolder.server;                server.performExpand(msgWindow);            }            else            {                var serverType = GetFolderAttribute(folderOutliner, folderResource, "ServerType");                if (serverType == "imap")                {                    var imapFolder = folderResource.QueryInterface(Components.interfaces.nsIMsgImapMailFolder);                    imapFolder.performExpand(msgWindow);                }            }        }    }    else if ((event.originalTarget.localName == "outlinercol") ||             (event.originalTarget.localName == "slider") ||             (event.originalTarget.localName == "scrollbarbutton")) {      // clicking on the name column in the folder pane should not sort      event.preventBubble();    }    else if (event.detail == 2) {      FolderPaneDoubleClick(row.value, event);    }    else if (gDBView && gDBView.isSearchView)    {      if (gSearchInput) gSearchInput.value ="";  //on input does not get fired for some reason      onSearchInput(null);      SetFocusThreadPane();    }}
meta: 5872	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5872/728727cafd21cdf40e3948a45a38ab6ae91baa1c/msgMail3PaneWindow.js/clean/mailnews/base/resources/content/msgMail3PaneWindow.js