C# Definition:

on Win8 work with Guid( "e6fdd21a-163f-4975-9c8c-a69f1ba37034" )

[ComImport, Guid ( "8016b7b3-3d49-4504-a0aa-2a37494e606f" ), InterfaceType ( ComInterfaceType.InterfaceIsIUnknown )]
interface IFileDialogCustomize : IFileDialog
{
    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void EnableOpenDropDown ( [In] int dwIDCtl );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void AddMenu ( [In] int dwIDCtl, [In, MarshalAs ( UnmanagedType.LPWStr )] string pszLabel );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void AddPushButton ( [In] int dwIDCtl, [In, MarshalAs ( UnmanagedType.LPWStr )] string pszLabel );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void AddComboBox ( [In] int dwIDCtl );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void AddRadioButtonList ( [In] int dwIDCtl );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void AddCheckButton ( [In] int dwIDCtl, [In, MarshalAs ( UnmanagedType.LPWStr )] string pszLabel,
                  [In] bool bChecked );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void AddEditBox ( [In] int dwIDCtl, [In, MarshalAs ( UnmanagedType.LPWStr )] string pszText );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void AddSeparator ( [In] int dwIDCtl );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void AddText ( [In] int dwIDCtl, [In, MarshalAs ( UnmanagedType.LPWStr )] string pszText );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void SetControlLabel ( [In] int dwIDCtl, [In, MarshalAs ( UnmanagedType.LPWStr )] string pszLabel );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void GetControlState ( [In] int dwIDCtl, [Out] out CDCONTROLSTATE pdwState );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void SetControlState ( [In] int dwIDCtl, [In] CDCONTROLSTATE dwState );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void GetEditBoxText ( [In] int dwIDCtl, [Out] IntPtr ppszText );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void SetEditBoxText ( [In] int dwIDCtl, [In, MarshalAs ( UnmanagedType.LPWStr )] string pszText );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void GetCheckButtonState ( [In] int dwIDCtl, [Out] out bool pbChecked );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void SetCheckButtonState ( [In] int dwIDCtl, [In] bool bChecked );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void AddControlItem ( [In] int dwIDCtl, [In] int dwIDItem,
                  [In, MarshalAs ( UnmanagedType.LPWStr )] string pszLabel );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void RemoveControlItem ( [In] int dwIDCtl, [In] int dwIDItem );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void RemoveAllControlItems ( [In] int dwIDCtl );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void GetControlItemState ( [In] int dwIDCtl, [In] int dwIDItem, [Out] out CDCONTROLSTATE pdwState );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void SetControlItemState ( [In] int dwIDCtl, [In] int dwIDItem, [In] CDCONTROLSTATE dwState );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void GetSelectedControlItem ( [In] int dwIDCtl, [Out] out int pdwIDItem );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void SetSelectedControlItem ( [In] int dwIDCtl, [In] int dwIDItem ); // Not valid for OpenDropDown
    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void StartVisualGroup ( [In] int dwIDCtl, [In, MarshalAs ( UnmanagedType.LPWStr )] string pszLabel );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void EndVisualGroup ( );

    [MethodImpl ( MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime )]
    void MakeProminent ( [In] int dwIDCtl );
}

VB Definition:

<ComImport> _
<Guid("TODO")> _
'TODO: Insert <InterfaceType(ComInterfaceType.InterfaceIsIUnknown)> _ if this doesn't derive from IDispatch
Interface IFileDialogCustomize
   TODO
End Interface

User-Defined Types:

None.

Notes:

Microsoft has provide a complete wrapper for this and other Windows 7 components in the Windows API Code Pack for Microsoft .NET: http://archive.msdn.microsoft.com/WindowsAPICodePack/Release/ProjectReleases.aspx?ReleaseId=4906