how to get IVsColorThemeService in VS2012/2013

Hi,

I need to access CurrentTheme.ThemeId of IVsColorThemeService in VS. Although it is delared as "public" inMicrosoft.VisualStudio.Shell.12.0.dll,  it seems that I could not use the types.  I defined my own com import interfaces but still have problems when I try to cast the object returned by GetService()...

		// no issue
		object dd = this.GetService(typeof(Microsoft.Internal.VisualStudio.Shell.Interop.SVsColorThemeService));
		// cast exception will be thrown
		IVsColorThemeService service= (IVsColorThemeService)this.GetService(typeof(SVsColorThemeService));

the followings is my imported interfaces.

namespace Microsoft.Internal.VisualStudio.Shell.Interop1
{

    [ComImport, Guid("BBE70639-7AD9-4365-AE36-9877AF2F973B"), TypeIdentifier, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), CompilerGenerated]
    public interface IVsColorEntry
    {
        void _VtblGap1_1();
        byte BackgroundType { get; }
        byte ForegroundType { get; }
        uint Background { get; }
        uint Foreground { get; }
    }

    [ComImport, CompilerGenerated, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), TypeIdentifier, DefaultMember("Item"), Guid("92144F7A-61DE-439B-AA66-13BE7CDEC857")]
    public interface IVsColorNames
    {
        void _VtblGap1_3();
        [return: MarshalAs(UnmanagedType.CustomMarshaler, MarshalType = "", MarshalTypeRef = typeof(EnumeratorToEnumVariantMarshaler), MarshalCookie = "")]
        IEnumerator GetEnumerator();
    }

    [ComImport, CompilerGenerated, DefaultMember("Item"), TypeIdentifier, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("413D8344-C0DB-4949-9DBC-69C12BADB6AC")]
    public interface IVsColorTheme
    {
        void _VtblGap1_2();
        Guid ThemeId { get; }
    }

    [ComImport, TypeIdentifier, CompilerGenerated, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("98192AFE-75B9-4347-82EC-FF312C1995D8"), DefaultMember("Item")]
    public interface IVsColorThemes
    {
        [return: MarshalAs(UnmanagedType.Interface)]
        IVsColorTheme GetThemeFromId([In] Guid ThemeId);
    }

    [ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), CompilerGenerated, Guid("EAB552CF-7858-4F05-8435-62DB6DF60684"), TypeIdentifier]
    public interface IVsColorThemeService
    {
        void _VtblGap1_4();
        IVsColorThemes Themes { [return: MarshalAs(UnmanagedType.Interface)] get; }
        IVsColorNames ColorNames { [return: MarshalAs(UnmanagedType.Interface)] get; }
        IVsColorTheme CurrentTheme { [return: MarshalAs(UnmanagedType.Interface)] get; }
    }


    [ComImport, InterfaceType(ComInterfaceType.InterfaceIsIUnknown), CompilerGenerated, Guid("0D915B59-2ED7-472A-9DE8-9161737EA1C5"), TypeIdentifier]
    public interface SVsColorThemeService
    {
    }


}

can anyone help me here?

Thanks,

Vince