instance.show();

public void Show()

            // Add a function that handles the AuthenticationCompleted event.
            _signin.add_authenticationCompleted(authenticationCompleted);
            
            // This function is invoked once the user has authenticated with Windows Live.
            function authenticationCompleted(sender, e) {
                // Hide the control.
                _signin.hide();
            
                _user = new Microsoft.Live.Messenger.User(e.get_identity());
                _user.add_signInCompleted(signInCompleted);
                _user.add_signedOut(signedOut);
                _user.signIn();
            }
            
            // This function is invoked once the signOut(...) method has completed.
            function signedOut(sender, e)
            {
                // Show the control so that the user may sign-in again.
                _signin.show();
            }