diff -r 000000000000 -r 2f259fa3e83a uifw/AvKon/aknhlist/inc/akntreeobserver.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/uifw/AvKon/aknhlist/inc/akntreeobserver.h	Tue Feb 02 01:00:49 2010 +0200
@@ -0,0 +1,79 @@
+/*
+* Copyright (c) 2006 Nokia Corporation and/or its subsidiary(-ies).
+* All rights reserved.
+* This component and the accompanying materials are made available
+* under the terms of "Eclipse Public License v1.0"
+* which accompanies this distribution, and is available
+* at the URL "http://www.eclipse.org/legal/epl-v10.html".
+*
+* Initial Contributors:
+* Nokia Corporation - initial contribution.
+*
+* Contributors:
+*
+* Description:  Observer interface for the tree structure.
+*
+*/
+
+
+#ifndef M_AKNTREEOBSERVER_H
+#define M_AKNTREEOBSERVER_H
+
+
+class CAknTree;
+class CAknTreeItem;
+
+
+/**
+ *  Observer interface for the tree structure.
+ *
+ *  Observers of the tree are notified of changes in the tree structure
+ *  through this interface with appropriate events.
+ *
+ *  @lib aknhlist.lib
+ *  @since S60 v3.2
+ */
+class MAknTreeObserver
+    {
+
+public:
+
+    /**  Tree events. */
+    enum TEvent
+        {
+        /** New item is added to the tree. */
+        EItemAdded,
+        /** Item is moved to another location in tree. */
+        EItemMoved,
+        /** Item is about to be removed from the tree. Observers are notified
+            with this event before the item is removed. */
+        EItemRemoveBegin,
+        /** Item is removed from the tree. */
+        EItemRemoveEnd,
+        /** Tree node is expanded. */
+        ENodeExpanded,
+        /** Tree node is collapsed. */
+        ENodeCollapsed,
+        /** Content of a item is changed (item need to be redrawn if visible). */
+        EItemModified,
+        /** Tree has been sorted. */
+        ETreeSorted
+        };
+
+    /**
+     * Notification of a tree event. The event is specified as a parameter.
+     *
+     * @param aEvent Tree event.
+     *
+     * @param aItem Pointer to the tree item that is concerned by the event.
+     *
+     * @param aDrawNow @c ETrue, if the view should be redrawn after the
+     *      event.
+     */
+    virtual void HandleTreeEvent( TEvent aEvent, CAknTreeItem* aItem,
+        TBool aDrawNow ) = 0;
+
+    };
+
+
+#endif // M_AKNTREEOBSERVER_H