--- a/mail/base/content/folderPane.js
+++ b/mail/base/content/folderPane.js
@@ -461,18 +461,21 @@ let gFolderTreeView = {
     return this._rowMap[aIndex];
   },
 
   /**
    * Returns an array of nsIMsgFolders corresponding to the current selection
    * in the tree
    */
   getSelectedFolders: function ftv_getSelectedFolders() {
+    let selection = this.selection;
+    if (!selection)
+      return [];
+
     let folderArray = [];
-    let selection = this._treeElement.view.selection;
     let rangeCount = selection.getRangeCount();
     for (let i = 0; i < rangeCount; i++) {
       let startIndex = {};
       let endIndex = {};
       selection.getRangeAt(i, startIndex, endIndex);
       for (let j = startIndex.value; j <= endIndex.value; j++) {
         if (j < this._rowMap.length)
           folderArray.push(this._rowMap[j]._folder);
@@ -1110,17 +1113,17 @@ let gFolderTreeView = {
       curLevel++;
       if (goOn)
         openLevel();
     }
     openLevel();
   },
 
   _tree: null,
-
+  selection: null,
   /**
    * An array of ftvItems, where each item corresponds to a row in the tree
    */
   _rowMap: null,
 
   /**
    * Completely discards the current tree and rebuilds it based on current
    * settings
@@ -1131,32 +1134,43 @@ let gFolderTreeView = {
       newRowMap = this._modes[this.mode].generateMap(this);
     } catch(ex) {
       Components.classes["@mozilla.org/consoleservice;1"]
                 .getService(Components.interfaces.nsIConsoleService)
                 .logStringMessage("generator " + this.mode + " failed with exception: " + ex);
       this.mode = "all";
       newRowMap = this._modes[this.mode].generateMap(this);
     }
+    let selectedFolders = this.getSelectedFolders();
+    if (this.selection)
+      this.selection.clearSelection();
     // There's a chance the call to the map generator altered this._rowMap, so
     // evaluate oldCount after calling it rather than before
     let oldCount = this._rowMap ? this._rowMap.length : null;
     this._rowMap = newRowMap;
 
     let evt = document.createEvent("Events");
     evt.initEvent("mapRebuild", true, false);
     this._treeElement.dispatchEvent(evt);
 
     if (this._tree)
     {
       if (oldCount !== null)
           this._tree.rowCountChanged(0, this._rowMap.length - oldCount);
       this._tree.invalidate();
     }
     this._restoreOpenStates();
+    // restore selection.
+    for each (let folder in Iterator(selectedFolders)){
+      if (folder) {
+        let index = this.getIndexOfFolder(folder);
+        if (index != -1)
+          this.selection.toggleSelect(index);
+      }
+    }
   },
 
   _sortedAccounts: function ftv_getSortedAccounts()
   {
       const Cc = Components.classes;
       const Ci = Components.interfaces;
       let acctMgr = Cc["@mozilla.org/messenger/account-manager;1"]
                        .getService(Ci.nsIMsgAccountManager);

new file mode 100644
--- /dev/null
+++ b/mail/test/mozmill/folder-tree-modes/test-unread-folders.js
@@ -0,0 +1,111 @@
+/* ***** BEGIN LICENSE BLOCK *****
+ *   Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is Thunderbird Mail Client.
+ *
+ * The Initial Developer of the Original Code is
+ * the Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2010
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   David Bienvenu <bienvenu@mozillamessaging.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+/*
+ * Test that the unread folder mode works properly. This includes making
+ * sure that the selected folder is maintained correctly when the view
+ * is rebuilt because a folder has become newly unread.
+ */
+
+var MODULE_NAME = "test-unread-folders";
+
+var RELATIVE_ROOT = "../shared-modules";
+var MODULE_REQUIRES = ["folder-display-helpers"];
+
+var rootFolder;
+var inboxSubfolder;
+var trashFolder;
+var trashSubfolder;
+
+const nsMsgFolderFlags = Components.interfaces.nsMsgFolderFlags;
+
+function setupModule(module) {
+  let fdh = collector.getModule("folder-display-helpers");
+  fdh.installInto(module);
+
+  rootFolder = inboxFolder.server.rootFolder;
+
+  // Create a folder as a subfolder of the inbox
+  inboxFolder.createSubfolder("UnreadFoldersA", null);
+  inboxSubfolder = inboxFolder.getChildNamed("UnreadFoldersA");
+
+  trashFolder = inboxFolder.server.rootFolder.getFolderWithFlags(
+    nsMsgFolderFlags.Trash);
+  trashFolder.createSubfolder("UnreadFoldersB", null);
+  trashSubfolder = trashFolder.getChildNamed("UnreadFoldersB");
+
+  // The message itself doesn't really matter, as long as there's at least one
+  // in the folder.
+  make_new_sets_in_folder(inboxFolder, [{count: 1}]);
+  make_new_sets_in_folder(inboxSubfolder, [{count: 1}]);
+}
+
+/**
+ * Switch to the all folders mode.
+ */
+function test_switch_to_all_folders() {
+  mc.folderTreeView.mode = "all";
+  be_in_folder(inboxFolder);
+}
+
+/**
+ * Switch to the unread folder mode.
+ */
+function test_switch_to_unread_folders() {
+  mc.folderTreeView.mode = "unread";
+}
+
+/**
+ * Test that inbox and inboxSubfolder are in view
+ */
+function test_folder_population() {
+  assert_folder_visible(inboxFolder);
+  assert_folder_visible(inboxSubfolder);
+}
+
+/**
+ * Test that a folder newly getting unread messages doesn't
+ * change the selected folder in unread folders mode.
+ */
+function test_newly_added_folder() {
+  make_new_sets_in_folder(trashFolder, [{count: 1}]);
+  assert_folder_visible(trashFolder);
+  if (mc.folderTreeView.getSelectedFolders()[0] != inboxFolder)
+    throw new Error("Inbox folder should be selected after new unread folder" +
+                    " added to unread view");
+}
+