public extern static bool ActivateActCtx(ActivationContextSafeHandle hActCtx, out IntPtr lpCookie);
        private static bool EnsureActivateContextCreated()
        {
            lock( _contextCreationLock )
            {
                if( !_contextCreationSucceeded )
                {
                    // Pull manifest from the .NET Framework install
                    // directory

                    string assemblyLoc = null;

                    assemblyLoc = typeof(Object).Assembly.Location;

                    string manifestLoc = null;
                    string installDir = null;
                    if( assemblyLoc != null )
                    {
                        installDir = Path.GetDirectoryName(assemblyLoc);
                        const string manifestName = "XPThemes.manifest";
                        manifestLoc = Path.Combine(installDir, manifestName);
                    }

                    if( manifestLoc != null && installDir != null )
                    {
                        _enableThemingActivationContext = new NativeMethods.ACTCTX();
                        _enableThemingActivationContext.cbSize = Marshal.SizeOf(typeof(NativeMethods.ACTCTX));
                        _enableThemingActivationContext.lpSource = manifestLoc;

                        // Set the lpAssemblyDirectory to the install
                        // directory to prevent Win32 Side by Side from
                        // looking for comctl32 in the application
                        // directory, which could cause a bogus dll to be
                        // placed there and open a security hole.
                        _enableThemingActivationContext.lpAssemblyDirectory = installDir;
                        _enableThemingActivationContext.dwFlags = NativeMethods.ACTCTX_FLAG_ASSEMBLY_DIRECTORY_VALID;

                        // Note this will fail gracefully if file specified
                        // by manifestLoc doesn't exist.
                        _activationContext = NativeMethods.CreateActCtx(ref _enableThemingActivationContext);
                        _contextCreationSucceeded = !_activationContext.IsInvalid;
                    }
                }

                // If we return false, we'll try again on the next call into
                // EnsureActivateContextCreated(), which is fine.
                return _contextCreationSucceeded;
            }
        }