public class BatchResultContextMenu: IShellExtInit, IContextMenu

        #region IContextMenu

        // IContextMenu

        int    IContextMenu.QueryContextMenu(uint hMenu, uint iMenu, int idCmdFirst, int idCmdLast, uint uFlags)

        void IContextMenu.GetCommandString(int idCmd, uint uFlags, int pwReserved, StringBuilder commandString, int cchMax)

        void IContextMenu.InvokeCommand (IntPtr pici)

    public interface IContextMenu3 : IContextMenu2 {

Interface IContextMenu3

Make sure your object explicitly lists all the IContextMenu interfaces or the shell may never call IContextMenu3.HandleMenuMsg2. For example:

public class ContextMenuHandler : IShellExtInit, IContextMenu, IContextMenu2, IContextMenu3

interface IContextMenu2 {

Interface IContextMenu2

    public interface IContextMenu3 : IContextMenu2 {

Interface IContextMenu3

        public static Guid IID_IContextMenu  = new Guid( 0x000214E4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 );

        public static Guid IID_IContextMenu2 = new Guid( 0x000214F4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 );

        public static Guid IID_IContextMenu3 = new Guid( 0xbcfce0a0, 0xec17, 0x11d0, 0x8d, 0x10, 0x0, 0xa0, 0xc9, 0xf, 0x27, 0x19);

    Public Shared IID_IContextMenu As Guid = New Guid(&H214E4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)

    Public Shared IID_IContextMenu2 As Guid = New Guid(&H2214F4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)